Metrics details The Bølling-Allerød interstadial (14,700–12,900 years before present) was characterized by rapid warming and sea level rise the response of the Arctic terrestrial cryosphere during this abrupt climate change remains thus far elusive Here we present a multi-proxy analysis of a sediment record from the northern Svalbard continental margin an area strongly influenced by sea ice export from the Arctic to elucidate sea level - permafrost erosion connections We show that permafrost-derived material rich in biospheric carbon became the dominant source of sediments at the onset of the Bølling-Allerød despite the lack of direct connections with permafrost deposits Our results suggest that the abrupt temperature and sea level rise triggered massive erosion of coastal ice-rich Yedoma permafrost followed by long-range sea ice transport towards the Fram Strait and the Arctic Ocean gateway we show how coastal permafrost is susceptible to large-scale remobilization in a scenario of rapid climate variability the study of past abrupt warming events offers the opportunity to understand the behaviour of permafrost in a scenario of rapid cryosphere retreat as well as place the modern anthropogenically-induced permafrost-climate feedbacks into a broader context of natural centennial-scale climate variability this indicates that a complete reorganization of OC reservoirs in Circumpolar Arctic soils must have taken place at some point during the last 20 kyr The vertical dashed line displays the onset of MWP-1A retrieved in the deeper part of the slope 80 km east of HH11-09GC allows us to demonstrate that our record is not confined to a local effect while the latter represents a valuable record from the Eurasian Arctic that covers the entirety of the last Termination and for which terrestrial biomarkers have also been analysed at high resolution with a strong influence of the BSIS that resulted in the deposition of mainly glacially-eroded material the impact of the BSIS on the site gradually weakened as the grounding line retreated more inland Main data from core HH11-09GC plotted against the core depth to ensure a better visualization of the extended deglaciation record a Compound specific radiocarbon pre-depositional ages for terrestrial C24:0 green and yellow dots respectively) with 1σ error bars; OC-normalized concentration of (b) cutin acids (green line and dots) and (c) lignin phenols (orange line and dots); relative abundances of (d) MeC37:4 (light blue line and dots) and (e) MeC38:4 alkenone (aqua green line and dots) referred to MeC37 and MeC38 groups respectively f OC-normalized concentration of brassicasterol (light purple line and dots); OC-normalized concentration of (g) IP25 (grey line and dots) (h) HBI III (light brown line and dots) and (i) HBI IV (brown line and dots) The vertical dashed lines highlight the temporal division between Holocene Blue triangles and numbers at the bottom represent median values of 13 modelled dating points with 1σ uncertainty (for visualization purposes the lowest age is not displayed in this plot because its core depth exceeds 300 cm) Black arrows and texts on both sides of the graph indicate what each corresponding biomarker is associated with following the relatively short period of intense terrestrial OC deposition identified in HH11-09GC (ca the late deglaciation and the entire Holocene were characterised by a low accumulation of biospheric carbon as expected for a core site far from any direct river input Lignin concentration (on average 0.35 mg g-1 OC) and CPI (on average 2.3) display values slightly higher than during the glacial period suggesting a small contribution from Holocene vegetation mixing with the locally sourced bedrock material likely reflecting changes in sea ice dynamics (cf IP25) and/or in the contributions from in situ production and laterally advected material which do not correspond to the expected depositional settings of the core site raises questions about the mechanisms behind the release of this pre-aged terrestrial OC and whether the high terrigenous deposition can be attributed to rapid climate change and sea level rise during the B-A Given the different pathways for land-to-ocean transport in the Eurasian Arctic during the B-A we considered four possible mechanisms to explain the delivery of ultra-high terrigenous OC to the core location: (A) local Arctic material from the Svalbard archipelago remobilized and transported by the BSIS ice streams; (B) freshwater discharge from the western Eurasian margin in response to the ice sheet retreat; (C) transport of land-derived material via a meltwater outburst involving the BSIS collapse; and (D) advection and melting of sediment-laden sea ice via the TPD we interpreted our combined biomarker findings alongside sediment properties and previous literature data the material would need to overcome the ice divide of the BSIS and move against the hydraulic gradient to reach northern Svalbard where the material could undergo degradation if the higher limit for sediment concentrations in sea ice were replicated it becomes reasonable to propose that sediment-laden sea ice export from the Eurasian Arctic could readily have been responsible for generating the observed deposit promoted the deposition of sea ice-advected sediments at the boundary between the Atlantic and Arctic domains the magnitude of sediment-laden sea ice export documented in this study is far from that described in modern studies We therefore infer a scenario of unprecedented coastal erosion during MWP1-A capable of producing a Yedoma-rich unit at the gateway to the Arctic Ocean through the export of sediment-laden sea ice within the TPD Further investigations from the Greenland Sea Fram Strait and Nordic Seas are needed to corroborate the large-scale nature of this event and elucidate the response of permafrost to rapid sea level rise and warming at 5-cm resolution for bulk geochemical analyses and at 5- for micropaleontological and IRD analyses (115 samples in total over the entire 466 cm core) Sediments for the current study were freeze-dried ground for homogenization and stored in glass vials prior to geochemical analyses at the Institute of Polar Sciences of the National Research Council in Bologna Beyond the Normarine18 calibration period (i.e. we applied the lowermost assessable ∆R correction 77 were then analyzed for specific biomarkers (4-cm resolution) Around 250-300 mg of sediment were oxidized in a 2 M NaOH aqueous solution under oxygen-free conditions in Teflon vessels using CEM Mars6 Microwave Digestion System (150 °C for 90 min) the samples were transferred into Falcon tubes and a known amount of internal standard (ethylvanillin) was added to each sample to estimate recovery rates Samples were centrifuged and then the liquid phase was transferred into pre-combusted glass tubes The solution was acidified (pH=1) with concentrated HCl and extracted twice with ethyl acetate The extracts were filtered with anhydrous Na2SO4 to remove excess water dried under N2 stream and redissolved in pyridine were derivatized at 50 °C for about 30 min with N,O-Bis(trimethylsilyl)trifluoroacetamide (BTSFA) with 1% trimethylchlorosilane (TMCS) The quantification of CuO oxidation products was performed via gas chromatography-mass spectrometry (GC-MS) using an Agilent 7820 A Gas Chromatograph coupled with a 5977B Mass Selective Detector in single ion monitoring (SIM) equipped with a Trajan SGE 30 m × 320 µm (0.25 µm-thick film) PB-1 capillary column The oven temperature ramp was set from 95 °C to 300 °C at a rate of 4 °C/min with a hold time of 10 min Quantification of lignin phenols was achieved through calibration curves obtained from commercially available standards (Sigma-Aldrich) Cutin acids were quantified against the concentration of the internal standard We reported the total lignin concentration as the sum of the 8 lignin-derived phenols and the total cutin concentration as the sum of the 8 cutin acids Hydrocarbons (HBIs and n-alkanes) and algal lipids (sterols, alkenones) were extracted following a slightly modified method from Tesi et al.113 A known amount of internal standards (7-hexylnonadecane 5α-Androstan-3β-ol) was added to ~1.5 g of sediments MeOH:H2O (9:1 v/v) solution at 70 °C for 1 h to complete saponification The neutral fraction was then extracted from the aqueous solution three times Extracts were dried under N2 stream and redissolved in HEX:DCM (3:2 v/v) Purification was performed using silica gel (60–200 µm) column chromatography n-alkanes and alkenones) was eluted with HEX:DCM (3:2 v/v) and the polar fraction (containing sterols) with MeOH:DCM (1:1 v/v) The polar fraction was then redissolved in DCM and subsampled and derivatized with BTSFA with 1% TMCS The apolar fraction was redissolved in MTBE:MeOH (3:1 v/v) with an excess NaBD4 and left at room temperature for an hour to transform alkenones into alkenols Excess NaBD4 was then neutralized by adding NH4Cl-saturated ultrapure water The aqueous solution was subsequently acidified with concentrated HCl and extracted with HEX:DCM (4:1 v/v) Reduced extracts were dried under N2 stream redissolved in pyridine and derivatized with BTSFA with 1% TMCS for GC-MS analysis The analyses of both apolar and polar fractions were performed via GC-MS using an Agilent 7820 A Gas Chromatograph coupled with a 5977B Mass Selective Detector in SIM For the analyses of the entire apolar fraction the oven temperature ramp was set from 60 °C to 250 °C at a rate of 10 °C/min and then up to 300 °C at a rate of 4 °C/min the oven temperature ramp was set from 70 °C to 200 °C at a rate of 8 °C/min The SIM peak areas of the individual HBIs were correlated with the SIM peak areas of the internal standard and a response factor was applied to account for the differences in mass spectral responses Alkanes were quantified using commercially available external standards after correcting for the internal standard Alkenones were quantified by converting the SIM results to total ion chromatogram (TIC) results using a correction factor (obtained by the analysis of concentrated samples over different concentrations) and comparing them to the response of the internal standard Relative abundances of methyl C38 and ethyl alkenones due to co-elution problems impeding the conversion of their SIM peak areas into TIC have been calculated based on the integrated peak areas from SIM mode only Results of the quantified compounds are shown as both MARs (Mass Accumulation Rates) and OC-normalized data CSRA data were obtained from specific high molecular weight n-alkanoic acids. We integrated different ranges of sediment depths (Supplementary Table 2) in order to collect a sufficient amount of material for the analysis (at least 100 µg of the selected compounds are necessary for radiocarbon dating) The different integrated depth for each sample corresponds to a period of 75 years according to our age-depth model Taking into account that the analytical uncertainty on the 14C age of the individual compounds is on average ca we thus considered the uncertainty caused by the sediment depth integration as negligible The purity and recovery of each FAME fraction were then checked via Gas Chromatography – Flame Ionization Detection (GC-FID) All data needed to evaluate the conclusions are available in the main text and/or in the supplementary materials. The Excel spreadsheet containing the complete dataset used in this work can be accessed at https://zenodo.org/record/8305777. 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Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily. Too many automated requests from this network Text description provided by the architects. The newest addition to Mungo Park Theatre breathes life into the city center of Allerød and will be the face of the theatre to the outside world. The new, square theatre building has a dynamic façade that creates visibility around the theatre’s activities. The façade is wooden and organized into modules, which gives the building a warm and welcoming atmosphere. The building was completed before Life Cycle Analysis became obligatory; however we did select the façade materials based on Life Cycle Analysis (LCA) and Life Cycle Cost (LCC) calculations to reduce the building’s environmental footprint This means that the façade consists of materials with a long life that are easy to maintain and recycle You'll now receive updates based on what you follow Personalize your stream and start following your favorite authors If you have done all of this and still can't find the email Metrics details but their underlying physical causes are not known Here we show that the release of heat from warm waters in the deep North Atlantic Ocean probably triggered the Bølling–Allerød warming and reinvigoration of the Atlantic meridional overturning circulation Our results are based on coupled radiocarbon and uranium-series dates along with clumped isotope temperature estimates from water column profiles of fossil deep-sea corals in a limited area of the western North Atlantic We find that during Heinrich stadial 1 (the cool period immediately before the Bølling–Allerød interstadial) the deep ocean was about three degrees Celsius warmer than shallower waters above This reversal of the ocean’s usual thermal stratification pre-dates the Bølling–Allerød warming and must have been associated with increased salinity at depth to preserve the static stability of the water column The depleted radiocarbon content of the warm and salty water mass implies a long-term disconnect from rapid surface exchanges is most consistent with a Southern Ocean source The Heinrich stadial 1 ocean profile is distinct from the modern water column that for the Last Glacial Maximum and that for the Younger Dryas suggesting that the patterns we observe are a unique feature of the deglacial climate system Our observations indicate that the deep ocean influenced dramatic Northern Hemisphere warming by storing heat at depth that preconditioned the system for a subsequent 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corals and implications for vital effects Rapid changes in the mechanism of ocean convection during the last glacial period Ice-shelf collapse from subsurface warming as a trigger for Heinrich events Circulation changes in the Faeroe-Shetland Channel correlating with cold events during the last glacial period (58–10 ka) Ocean subsurface warming as a mechanism for coupling Dansgaard-Oeschger climate cycles and ice-rafting events A model for the global variation in oceanic depth and heat-flow with lithospheric age North Atlantic ventilation of “southern-sourced” deep water in the glacial ocean Evidence from the Northeastern Atlantic basin for variability in the rate of the meridional overturning circulation through the last deglaciation Glacial–interglacial circulation changes inferred from 231Pa/230Th sedimentary record in the North Atlantic region Rapid climate change and conditional instability of the glacial deep ocean from the thermobaric effect and geothermal heating An ocean large-eddy simulation model with application to deep convection in the Greenland Sea Open-ocean deep convection due to thermobaricity 1 Rapid changes of glacial climate simulated in a coupled climate model Bifurcations of the Atlantic thermohaline circulation in response to changes in the hydrological cycle A high-resolution record of atmospheric 14C based on Hulu Cave speleothem H82 Movement of deep-sea coral populations on climatic timescales Deep-sea scleractinian coral age and depth distributions in the northwest Atlantic for the last 225,000 years IntCal09 and Marine09 radiocarbon age calibration curves High-temperature environments of human evolution in East Africa based on bond ordering in paleosol carbonates Methods and limitations of ‘clumped’ CO2 isotope (Δ47) analysis by gas-source isotope ratio mass spectrometry 13C-18O bonds in carbonate minerals: a new kind of paleothermometer Clumped isotope calibration of modern deep sea corals and implications for vital effects Glacial water mass geometry and the distribution of δ13C of total CO2 in the Western Atlantic Ocean The timing of deglacial circulation changes in the Atlantic Deep Atlantic circulation during the Last Glacial Maximum and deglaciation On the abyssal circulation in the glacial Atlantic Isotopically depleted carbon in the mid-depth South Atlantic during the last deglaciation Patterns of deglacial warming in the Pacific Ocean: a review with emphasis on the time interval of Heinrich event 1 Changes in North Atlantic deep-sea temperature during climatic fluctuations of the last 25,000 years based on ostracode Mg/Ca ratios South Atlantic interocean exchange as the trigger for the Bølling warm event A high-resolution absolute-dated late Pleistocene monsoon record from Hulu Cave Changing atmospheric Delta C-14 and the record of deep water paleoventilation ages Coupling of surface temperatures and atmospheric CO2 concentrations during the Palaeozoic era ‘Clumped isotope' thermometry in foraminifera diapycnal mixing and the abyssal circulation Warming of the tropical Atlantic Ocean and slowdown of thermohaline circulation during the last deglaciation Intermediate and deep water paleoceanography of the northern North Atlantic over the past 21,000 years Mediterranean Sea surface radiocarbon reservoir age changes since the last glacial maximum Proliferation and demise of deep-sea corals in the Mediterranean during the Younger Dryas Rapid fluctuations in the deep North Atlantic heat budget during the last glacial period Rapid transient changes in northeast Atlantic deep water ventilation age across Termination 1 The Southern Ocean’s role in carbon exchange during the Last Deglaciation Ventilation of the deep Southern Ocean and deglacial CO2 rise Extreme deepening of the Atlantic overturning circulation during deglaciation No signature of abyssal carbon in intermediate waters off Chile during deglaciation Deglacial radiocarbon history of tropical Atlantic thermocline waters: absence of CO2 reservoir purging signal Evidence from the high-latitude North Atlantic for variations in Antarctic Intermediate water flow during the last deglaciation Glacial surface temperatures of the Southeast Atlantic Ocean Abrupt changes in Antarctic Intermediate Water circulation over the past 25,000 years Deglacial variability of Antarctic Intermediate Water penetration into the North Atlantic from authigenic neodymium isotope ratios Deglacial variability in the surface return flow of the Atlantic meridional overturning circulation On the link between the two modes of the ocean thermohaline circulation and the formation of global-scale water masses Abyssal Atlantic circulation during the Last Glacial Maximum: constraining the ratio between transport and vertical mixing The role of deep ocean circulation in setting glacial climates A deep-sea coral record of North Atlantic radiocarbon through the Younger Dryas: Evidence for Intermediate/Deep water reorganization Radiocarbon and stable isotope constraints on Last Glacial Maximum and Younger Dryas ventilation in the western North Atlantic Download references We also thank the captain and crew of the RV Atlantis cruise AT7-35 and the WHOI Deep Submergence Alvin and ABE groups Division of Geological and Planetary Sciences collected the 14C and Δ47 data and compiled the benthic δ13C sections facilitated and oversaw the 14C measurements and J.M.E facilitated and oversaw the Δ47 measurements facilitated and oversaw the U-series measurements All authors contributed to the interpretation and preparation of the final manuscript The authors declare no competing financial interests Sites of sample collection in the North Atlantic Two different modern corals were selected to determine which cleaning method did not bias Δ47 temperatures A live-when-collected coral with a growth temperature of 3.9 °C (a) and a coral with an Fe–Mn crust and a 14C age matching that of the modern water column from 5 °C waters in the Southern Ocean (b) were selected for the cleaning study We found that physical cleaning with a Dremel tool gave accurate Δ47–temperature reconstructions This schematic describes the box model and equations used to calculate the effect of geothermal heat on ocean temperatures V is the volume fraction of the northern or southern box q is the overturning rate of the northern or southern box kv is the vertical mixing coefficient and Fgh is the geothermal heat flux (0.1 W m−2) The transient-state solution for the box model in Extended Data 3 The vertical diffusivity was kept constant and the Southern Hemisphere restoring temperature at 277 K We find that there is a rapid warming within the first few thousand years (denoted by the black box) (Points in c and d that are above the atmospheric value are connected with a dashed line instead of a solid line.) Uncertainties are 2σ error ellipses except for the Iberian margin and Mediterranean records a, A comparison of the Mg/Ca–temperature and Δ14C record from the Iberian margin57 with the record from our site The Iberian margin shows a warming at the beginning of the Bølling–Allerød but not an abrupt mid-15-kyr warming Asterisks indicate corals which have either a high δ234Ui or a Δ14C above the atmospheric value this open-system behaviour changes the Δ14C values but does not change calendar ages much on this plot Δ14C measurements at the Iberian margin also show that the water bathing the Iberian margin is distinct from the warm and Δ14C-depleted water at our site Black dots indicate the latitudes and depths of cores used to make the sections The time intervals compiled are as follows: Holocene (0–10 kyr ago; a) Last Glacial Maximum (19–22 kyr ago; f) salty and δ13C-depleted water from the south lay below cold intermediate waters changed more than deeper waters the δ13C distribution seen today had been established while thought to be a return to Heinrich-like water masses is structured differently than the late-HS1 section and was a progression towards the Holocene water column configuration (a) This file comprises 2 sheets: The first has the raw data for samples and standards run during all sessions; the second has the pertinent information for the heated gases run during each session and was used for sample correction Download citation a shareable link is not currently available for this article International Journal of Earth Sciences (2023) Progress in Earth and Planetary Science (2022) was one of the more prominent climate events punctuating the end of the last glaciation but the underlying physical mechanisms driving it remain unclear Nivedita Thiagarajan and colleagues use a coral data set to examine the intermediate depth circulation of the ocean at the time The data suggest that a layer of warm water lay in the deep North Atlantic during the Heinrich stadial 1 cool period that preceded the Bølling–Allerød interstadial This warm water served as a heat reservoir that kick-started the resumption of vigorous ocean circulation Sign up for the Nature Briefing newsletter — what matters in science our brand guidelines & how to contact our staff BOULDER—By simulating 8,000 years of climate with unprecedented detail and accuracy a team led by scientists from the University of Wisconsin–Madison and the National Center for Atmospheric Research (NCAR) has found a new explanation for the last major period of global warming which occurred about 14,500 years ago In a period called the Bølling-Allerød warming global sea level rose by 16 feet and temperatures in Greenland soared by up to 27 degrees Fahrenheit over several hundred years The new study shows how increased carbon dioxide and a release of ocean-stored heat could have combined to trigger the warming Findings from the experiment appear in the July 17 issue of Science the National Science Foundation (NSF) Simulations were conducted on the Community Climate System Model (CCSM) which is a collaborative effort based at NCAR and supported primarily by NSF and DOE we need to unravel what happened in Earth's past This study is an important step toward better understanding of how the world's climate could change abruptly over the coming centuries especially with increasing melting of the ice caps She is co-director of the experiment along with Zhengyu Liu (University of Wisconsin–Madison) Liu and Otto-Bliesner are first and second authors of the Science paper Modeling the details for thousands of years Because climate modeling requires so much computer time previous simulations of past climate have either used highly complex models to study relatively short periods (a century or two) or simpler models to look at longer periods (thousands of years) This study is the first time a comprehensive interactive model of the global atmosphere and ocean has portrayed thousands of years of climate scientists jump-started the CCSM with known changes in Earth's orbit and in carbon dioxide concentration deduced from ice cores and other evidence They then observed how the atmosphere and ocean responded The results were in close agreement with temperatures and glacial coverage as deduced from fossil and geologic records The study examined the period from 22,000 to 14,000 years ago as Earth emerged in fits and starts from the extreme cold of the last ice age Temperatures rose from about 21,000 to 19,000 years ago then cooled again after glacial meltwater weakened the Atlantic Ocean's warming "conveyor belt," also called the thermohaline circulation One mystery the scientists hoped to solve was why global warming resumed so abruptly and strongly during the Bølling-Allerød period Previous studies using simpler models had speculated that a sudden shift in the Atlantic Ocean conveyor belt might have caused the Bølling-Allerød warming the new work with the CCSM suggests that three factors each contributed about a third of the warming: the enormous subsurface heat that had accumulated for 3,000 years erupted like a volcano and popped out over decades," says Liu "This huge heat flux melted the sea ice and warmed up Greenland." The current study is only the first phase of a larger project called Transient Simulation of Climate Evolution over the Last 21,000 Years (TraCE-21000) the researchers will continue to move their simulation of past climate forward through the present and out to the year 2300 the project will employ a total of close to five million computing processor hours at DOE's Oak Ridge National Laboratory including time on the world's fastest supercomputer for unclassified research "We've never been able to recreate climate over this long a period with so much detail and accuracy," says Otto-Bliesner "Being able to successfully simulate thousands of years of past climate for the first time with a comprehensive climate model is a major scientific achievement." The interdisciplinary study team includes ocean and computing experts from a wide range of universities "It is a huge—and very successful—collaboration," says Liu Title: "Transient Simulation of Last Deglaciation with a New Mechanism for Bølling-Allerød Warming" Publication: Science See all News AMS to hold special session as Hurricane Katrina's 20th anniversary looms This material is based upon work supported by the NSF National Center for Atmospheric Research, a major facility sponsored by the U.S. National Science Foundation and managed by the University Corporation for Atmospheric Research. Any opinions, findings and conclusions or recommendations expressed in this material do not necessarily reflect the views of the U.S. National Science Foundation. The dates displayed for an article provide information on when various publication milestones were reached at the journal that has published the article activities on preceding journals at which the article was previously under consideration are not shown (for instance submission Quaternary InternationalCitation Excerpt :Our attempt to characterize intrasite basalt variability at Nataeł Na’ represents one of the first systematic efforts to geochemically characterize culturally modified basalt in Alaska (see Rains such geochemical studies have met with broad success when applied to obsidian (Goebel et al. but the abundance of basalt in the Alaskan lithic landscape and the geochemical similarity between distinct flows (especially compared to obsidian) have thus far prevented a comprehensive study of this lithic raw material (but see Handley and Easton 2022 for a study similar to our own in the Yukon) basalt was a critically important resource utilized heavily by Pleistocene peoples at Nataeł Na’ and across the Alaska Range uplands (Blong All content on this site: Copyright © 2025 Elsevier B.V. humans manipulate their environments the most how far can we push it before something drastic happens Scientists are calling for a better understanding of past extreme climate change events in an attempt to anticipate future changes The paper describes past abrupt climate changes what led up to the “tipping points” for those events and what followed “We've been putting a lot of chemicals into the atmosphere and changing the heat of the atmosphere for a long time and really intensively for 150 years,” Barton said complex systems are potentially vulnerable if you push too much.” Barton studies Earth’s many systems — specifically the water cycle and landscapes — and how humans alter these systems “People tend to look at how far you can push things before suddenly everything changes,” Barton said “And that's what's considered the tipping point.” For a complex systems specialist like Barton almost everything can be viewed as systems or cycles and the decay returns nutrients to the soil Water cycles through the Earth in different forms like rain Some of Earth’s major systems include the hydrosphere (water) the atmosphere (air) and the cryosphere (ice) This research on tipping points looks at the history of these systems to quantify small changes that can lead up to an abrupt while also measuring how one abrupt change can trigger abrupt changes in other systems The paper explores prior research with sediment cores in the Gulf of Alaska dust records in North Africa and ice cores from Greenland All of this prehistoric data gives Earth system modelers and scientists a better idea of what Earth was really like hundreds of thousands of years ago Scientists have also been extensively studying Earth’s oceans This includes the current levels of salt and oxygen changes in circulation patterns and influxes of fresh water from melting ice sheets Current ocean conditions can be compared to historic data gathered from the composition of the ocean floor to make inferences about past ocean currents This figure from the paper shows the cascading effects of the sudden temperature increase 14,000 years ago This rapid climate change event is known as the Bølling Allerød onset and the cascading effects were measured around the globe — including dangerously low levels of oxygen in the ocean near Alaska abrupt increases in methane concentration in the atmosphere in Antarctica and an increase in tree cover in Western Europe The authors note past instances of extreme climate events happening so quickly that humans either had difficulties adapting The authors note the cooling may have been caused by a natural phenomenon — volcanic eruptions The vegetation and farming changes were so extreme that people experienced famine and societal reorganization This timing correlates with the transformation of the Eastern Roman Empire The authors note how climate events centuries ago triggered drastic changes or even collapse in ancient civilizations due to unforeseen societal vulnerabilities which was located in present-day Southeast Asia The people living in Angkor altered the natural water cycle by diverting water to grow crops the water system in that region became so strained that it passed a tipping point The system couldn’t handle more intense droughts and floods Arizonans know that the last few years have been drier and hotter than usual Barton said it’s not yet clear whether we’ve passed a tipping point in the Southwest region It’s normal to see slight fluctuations in precipitation and temperature year to year But recent studies of ancient climate make Barton wonder if the drier weather patterns have become the new normal for our lifetimes Barton also noted that researchers still don’t know why some weather systems change past monsoon rains have shifted without warning and for unknown reasons This can be catastrophic for human populations as those who depend on the monsoon experience intense drought while others do not have the infrastructure to handle the influx of water There are still gaps in this field of research More raw data needs to be collected and quantified and some existing data lacks the precision and quality needed to create test models and simulate future abrupt changes The researchers also call for more analysis on the interactions between environmental systems and human societies during periods of climate change improvements in Earth system models will help scientists be able to simulate possible abrupt changes humans may see in the near future Current models are very good at simulating more gradual climate change but are not yet able to simulate well-documented past abrupt changes The authors hope this paper raises awareness of the field and that more people will understand how analyzing the long-term past could help us in the near future one component of tipping points research is identifying early warning signals These are smaller fluctuations in a system before an abrupt change The authors say these warning signals exist it can be challenging to trace how small changes in one system can warn of an abrupt change in another there were abnormal shifts in the climates of the North Pacific Ocean region and around Greenland before the major melting of Earth’s last ice age “The whole system can drop into a different state … How do we know when we're getting too close?” The authors leave the reader with this final thought: “As humans We are now well aware that complex systems including the coupled social and ecological systems that now dominate our planet If we cannot model abrupt change in the past we cannot hope to predict them in the future.” The paper “Past abrupt changes, tipping points and cascading impacts in the Earth system” published July 29 and is co-authored by more than 30 researchers from across the world a first-generation college student from Gilbert will graduate with a bachelor’s degree in urban… Arizona State University welcomed academics experts and journalists who focus on environmental and climate issues for… By Meghan Finnerty and Megan NeelyArizona State University has a lot of insects — and for good reason Metrics details Palaeoecological reconstructions of the American Midwest during the last deglaciation suggest the expansion of parkland biomes lacking modern analogues Despite their spatial extent and persistence over several millennia the landscape configuration and environmental drivers for the ‘no analogue’ biomes remain speculative Here we use regression analysis linking settlement-era forest composition and wetland extent to identify specific trees and forest units strongly indicative of high wetland prevalence We then recompile a regional pollen time series to show transient increases in these flood-tolerant trees with prominent peaks during the Bølling–Allerød interstadial (~14.6–12.8 thousand years ago) and analyses of settlement-era forest composition and wetland prevalence suggest the establishment of extensive deglacial wetlands in the American Midwest (40–60% of land cover) wetland was possibly supported by southward discharge of Laurentide Ice Sheet meltwater during the Bølling–Allerød The timing of this wetland expansion and its mid-latitude location have implications for deglacial methane source dynamics; our estimate of ~11 Tg yr−1 of methane is comparable to the northern source enhancement modelled from ice-core records Regional decline of the Laurentide Ice Sheet meltwater discharge at the onset of the Younger Dryas (~12.8–11.7 thousand years ago) explains in part why these no-analogue wetland-rich parklands sharply declined and geologic methane emissions constrained by dual stable isotopic CH4 ice core records High-resolution interpolar difference of atmospheric methane around the Last Glacial Maximum Old carbon reservoirs were not important in the deglacial methane budget Rapid early development of circumarctic peatlands and atmospheric CH4 and CO2 variations Evidence for elevated emissions from high-latitude wetlands contributing to high atmospheric CH4 concentration in the early Holocene Rapid expansion of northern peatlands and doubled estimate of carbon storage Insights and issues with estimating northern peatland carbon stocks and fluxes since the Last Glacial Maximum Peatland initiation and carbon accumulation in China over the last 50,000 years Accumulation and release of methane from clathrates below the Laurentide and Cordilleran ice sheets Flooding of the continental shelves as a contributor to deglacial CH4 rise Abrupt onset and termination of the African Humid Period Potential carbon loss associated with post-settlement wetland conversion in southern Ontario Holocene peatland and ice-core data constraints on the timing and magnitude of CO2 emissions from past land use Late-Quaternary vegetation dynamics in North America: scailing from taxa to biomes Modern analogs in Quaternary paleoecology: here today Variations in tree cover in North America since the last glacial maximum Vegetation history since the Last Glacial Maximum in the Ozark highlands (USA): a new record from Cupola Pond Climatic and megaherbivory controls on late-glacial vegetation dynamics: a new Expanded response-surfaces: a new method to reconstruct paleoclimates from fossil pollen assemblages that lack modern analogues Deglacial hydroclimate of midcontinental North America The timing and nature of late Quaternary vegetation changes in the northern Great Plains USA and Canada: a re-assessment of the spruce phase Late Quaternary paleoenvironments of an ephemeral wetland in North Dakota USA: relative interactions of ground-water hydrology and climate change Mastodons and mammoths in the Great Lakes region USA and Canada: new insights into their diets as they neared extinction.Geogr Late Pleistocene glacial transitions in North America altered major river drainages The role of groundwater in the Amazon water cycle: 1 Gradual demise of a thin southern Laurentide Ice Sheet recorded by Mississippi drainage Reconciling records of ice streaming and ice margin retreat to produce a palaeogeographic reconstruction of the deglaciation of the Laurentide Ice Sheet Hydroseral development in southern Ontario: patterns and controls The DeKalb mounds of northeastern Illinois as archives of deglacial history and postglacial environments The North American hydrologic cycle through the last deglaciation Environmental changes of a shallow kettle lake catchment in a young glacial landscape (Sumowskie Lake catchment) in Northern Forested Wetlands: Ecology and Management (eds Gradient analysis of Larix laricina dominated wetlands in Canada’s southeastern boreal forest Using forest structure to predict the distribution of treed boreal peatlands in Canada The structure of Holocene climate change in mid-latitude North America Glacial isostatic adjustment of the Laurentian Great Lakes basin: using the empirical record of strandline deformation for reconstruction of early Holocene paleo-lakes and discovery of a hydrologically closed phase The Kankakee Torrent and other large meltwater flooding events during the last deglaciation and variable responses to early Holocene midcontinental drying in North America Signatures of human impact: size distributions and spatial organization of wetlands in the Prairie Pothole landscape Long-term peat accumulation in temperate forested peatlands (Thuja occidentalis swamps) in the Great Lakes region of North America Response of black ash wetland gaseous soil carbon fluxes to a simulated emerald ash borer infestation Presence of lakes and wetlands decreases resilience of jack pine ecosystems to late-Holocene climatic changes Novel and lost forests in the upper Midwestern United States from new estimates of settlement-era composition Global patterns of groundwater table depth Giant beaver palaeoecology inferred from stable isotopes The biogeography of aquatic macrophytes in North America since the Last Glacial Maximum Integrating aquatic and terrestrial components to construct a complete carbon budget for a north temperate lake district A new terrestrial palaeoenvironmental record from the Bering Land Bridge and context for human dispersal Hydrological changes in eastern Europe during the last 40,000 yr inferred from biomarkers in Black Sea Sediments Bipolar carbon and hydrogen isotope constraints on the Holocene methane budget Dyke, A. S., Moore, A. & Robertson, L. Deglaciation of North America Open File 1574 (Geological Survey of Canada, 2003); https://doi.org/10.4095/214399 Williams, J. W. et al. 2004 Late Quaternary North American Vegetation Dynamics Data (NOAA, accessed 26 February 2019); https://www.ncdc.noaa.gov/paleo/study/5973 Stocker, B. D., Yu, Z., Massa, C. & Joos, F. Global Peatland Carbon Balance and Land Use Change CO2 Emissions through the Holocene (ORNL DAAC, 2017); https://doi.org/10.3334/ORNLDAAC/1382 North America Rivers and Lakes (USGS, 2006); https://go.nature.com/2VPtPqo The ancestral Mississippi drainage archived in the late Wisconsin Mississippi deep-sea fan Ice streams in the Laurentide Ice Sheet: a new mapping inventory neotoma: a programmatic interface to the neotoma paleoecological database Quantifying pollen–vegetation relationships to reconstruct ancient forests using 19th-century forest composition and pollen data Rapid responses of the prairie-forest ecotone to early Holocene aridity in mid-continental North America Goring, S. Settlement-Era Gridded Tree Composition, Midwestern US: Level 1 (Environmental Data Initiative, accessed 22 April 2019); https://doi.org/10.6073/pasta/aa0ef9828d41569a96651b056ad89fb3 Cogbill, C. Settlement-Era Tree Composition, Ohio: Level 1 (Environmental Data Initiative, accessed 22 April 2019); https://doi.org/10.6073/pasta/9df301adbfd619fa474e1041f0070c05 A simple hydrologic framework for simulating wetlands in climate and Earth system models Statistically-estimated tree composition for the northeastern United States at Euro-American settlement Classification and regression trees: a powerful yet simple technique for ecological data analysis Random forests for classification in ecology Postglacial rise and decline of Ostrya virginiana (Mill.) K in eastern North America: predictable responses of forest species to cyclic changes in seasonality of climates Response of interior North America to abrupt climate oscillations in the North Atlantic region during the last deglaciation Volume and routing of late-glacial runoff from the southern Laurentide Ice Sheet Reconstruction of North American drainage basins and river discharge since the Last Glacial Maximum The Underestimated Role of Temperate Wetlands in the Late Quaternary Terrestrial Carbon Cycle Download references We acknowledge funding for this research from the University of Toronto Centre for Global Change Science and the Connaught International Scholarship for Doctoral Students to E.B and from the Natural Sciences and Engineering Research Council (Canada) to S.A.F We thank the many contributors to the Neotoma database for making pollen datasets available for further analyses Fan for sharing the water-table depth simulation results Present address: Ecohydrology Research Group conceived the study with guidance from S.A.F performed the analyses and wrote the first draft of the manuscript with input from H.S and S.A.F All authors contributed to the interpretation of the results and contributed to revising and improving the text and figures Peer review information Primary Handling Editor: James Super List of Neotoma pollen records used in this study Download citation DOI: https://doi.org/10.1038/s41561-020-00670-4 Metrics details One of the most abrupt and yet unexplained past rises in atmospheric CO2 (>10 p.p.m.v in two centuries) occurred in quasi-synchrony with abrupt northern hemispheric warming into the Bølling/Allerød Here we use a U/Th-dated record of atmospheric Δ14C from Tahiti corals to provide an independent and precise age control for this CO2 rise We also use model simulations to show that the release of old (nearly 14C-free) carbon can explain these changes in CO2 and Δ14C The Δ14C record provides an independent constraint on the amount of carbon released (~125 Pg C) in line with observations of atmospheric CH4 and terrigenous biomarkers that thawing permafrost in high northern latitudes could have been the source of carbon possibly with contribution from flooding of the Siberian continental shelf during meltwater pulse 1A Our findings highlight the potential of the permafrost carbon reservoir to modulate abrupt climate changes via greenhouse-gas feedbacks WD and ΔTANT on their own independent chronology All individual data points are plotted with ±1σ in both age and Δ14C IntCal13 was approximated by a linear trend with either −0.04‰ per year (black solid line) or −0.10‰ per year (black dashed line) Tahiti data were analysed for break points with two different models (see Methods) For the non-linear (NL) model (cyan lines) two data points at beginning of the Tahiti data Δ14C anomaly from the IntCal13 data and the eight points around the local minimum (black open circles) were averaged plotted with ±1σ in both age and Δ14C (bold large black open circles) and further analysed The anomaly in the Tahiti Δ14C data following the linear model is Δ(Δ14C)=−54±8‰ in Δ(age)=207±95 years and following the NL model: Δ(Δ14C)= −58±14‰ in Δ(age)=258±53 years We therefore assume that reservoir ages did not change over the last 15 kyr in the central low-latitude Pacific and the Δ14C signal based on Tahiti corals is not based on local effects but indeed a recorder of atmospheric Δ14C changes All our tests therefore indicate that the Tahiti Δ14C drop at 14.6 kyr BP is caused by carbon cycle changes This is our working hypothesis on which all else is based on but note that its failure cannot entirely be ruled out Simulated true atmospheric CO2 rise (black bold line) and how the signal might be recorded in EDC (dashed red line) after filtering for gas enclosure and shifted by 50 years to meet the data (c) Simulated peak height in atmospheric Δ14C (grey areas) as function of length of carbon release and of the Δ14C depletion (d) Simulated peak height in atmospheric CO2 (dark blue area) as function of length of carbon release simulations result with the AMOC in either a weak or a strong mode are combined spanning a range of results Magenta square and circle in c,d mark results of our best-guess scenario for Δ14C and CO2 We colour coded the areas in the parameter space where simulation results agree with the EDC CO2 data (d light blue) and with the interpretation of the Tahiti Δ14C data (c The latter are modified for background linear trends already contained in IntCal13 based on other processes original (black) and 100 years running mean (orange) Both marine- and terrestrial-based δ13CO2 simulations fall within the uncertainties of the measurements before 14.6 kyr BP The small rise in δ13CO2 after 14.4 kyr BP indicates that directly after the onset of the B/A other processes released less δ13C-depleted carbon to the atmosphere CO2 outgassing from warm oceanic surface waters On the basis of the data uncertainty of δ13CO2 in EDC it is still impossible to clearly identify if the released carbon was of marine or terrestrial origin The Shelf Flooding Hypothesis is explained in detail in the next section and some more details on our assumptions on 14C are found in the methods The time series is plotted in two different colours because of the break in the x axis scale at 50 kyr BP Red labelled arrows highlight the time which past since NGRIP was similar as warm as during the B/A (32 kyr since D/O event 12) and since the previous significant warming before the B/A (13 kyr since D/O 3) Results41 show a polar projection of the NH from 20 °N northwards are based on soil temperature and distinguish land with ice (dark blue) seasonal frozen (light blue) and not frozen (red) Present day coastlines are sketched in thin black lines Magenta points mark potential core sites (Siberian Shelf Sea of Okhotsk) from which future 14C measurements on terrigenous material might verify the age of permafrost possible thawed around 14.6 kyr BP (suggested green areas) All these modern data indicate that old carbon in permafrost exists nowadays and potentially was more abundant and older during glacial times In which region the thawing of permafrost finally happened might be verified by future 14C measurements on terrigenous organic material that are retrieved from marine sediments in the suggested coastal seas It will then be possible to finally attribute the size of the released carbon to either a pure thermodynamically thawing at the southern edge of the permafrost area or to a contribution from flooding the Siberian Shelf during MWP-1A we calculate that a 33% reduction in the proposed carbon released to the atmosphere (85 instead of 125 Pg C) still fulfils the data constrains given by the Tahiti Δ14C record our suggested old soil carbon release during permafrost thawing at 14.6 kyr BP requires that the same carbon sources were not tapped during other events within Termination I 14C measurements on terrigenous material might clarify how old the carbon released from permafrost was or if earlier CO2 rises might already have consumed the old It is important to quantify the feedback of this GHG forcing on climate to better understand the impact of the abrupt GHG changes during the last deglaciation Since the abrupt GHG changes are contemporaneous with the onset of the B/A (in the North) and the beginning of the ACR (in the South) the sequence of the associated bipolar climate linkages are of particular interest also smaller GHG spikes bear the potential to have a substantial effect on the Antarctic temperature response when compared with impacts caused by AMOC changes but a compelling explanation remains elusive and further testing of permafrost thawing as a possible alternative interpretation is needed Combining the linear and non-linear approach brings high confidence that the Δ14C drop started at around 14.6 kyr BP we first subtract the mean Δ14C value of terrestrial carbon at the LGM in the model (−50‰) before a further reduction in Δ14C signature is realised by the radioactive decay of 14C (half-life time of 5,730 years) Carbon isotope constraints on the deglacial CO2 rise from ice cores Ventilation of the deep Southern Ocean and deglacial CO2 Rise Synchronous change in atmospheric CO2 and Antarctic temperature during the last deglacial warming The Antarctic ice core chronology (AICC2012): an optimized multi-parameter and multi-site dating approach for the last 120 thousand years Abrupt rise in atmospheric CO2 at the onset of the Bølling/Allerød: in-situ ice core data versus true atmospheric signals Comparison of 14C and U-Th ages in corals from IODP #310 cores offshore Tahiti 800,000 Years of abrupt climate variability IntCal13 and Marine13 radiocarbon age calibration curves 0-50,000 years cal BP Towards radiocarbon calibration beyond 28 ka using speleothems from the Bahamas Marine-derived 14C calibration and activity record for the past 50,000 years updated from the Cariaco Basin Assessing influences on speleothem dead carbon variability over the Holocene: implications for speleothem-based radiocarbon calibration A complete terrestrial radiocarbon record for 11.2 to 52.8 kyr B.P Correction of accelerator mass spectrometry 14C ages measured in planktonic foraminifera: paleoceanographic implications Dependence of abrupt Atlantic meridional ocean circulation changes on climate background states Readjustment of glacial radiocarbon chronologies by self-consistent three-dimensional ocean circulation modeling An oceanic origin for the increase of atmospheric radiocarbon during the Younger Dryas Glacial-interglacial dynamics of Antarctic firn columns: comparison between simulations and ice core air δ15N measurements Impurity-controlled densification: a new model for stratified polar firn An ice core record of near-synchronous global climate changes at the Bølling transition Atmospheric CO2 concentrations over the last glacial termination High-resolution Greenland ice core data show abrupt climate change happens in few years CO2 record in the Byrd ice core 50,000-5,000 years BP Dual modes of the carbon cycle since the Last Glacial Maximum A record of atmospheric CO2 during the last 40,000 years from the Siple Dome Tightened constraints on the time-lag between Antarctic temperature and CO2 during the last deglaciation Marine radiocarbon evidence for the mechanism of deglacial atmospheric CO2 rise Radiocarbon age anomaly at intermediate water depth in the Pacific Ocean during the last deglaciation Ice-sheet collapse and sea-level rise at the Bolling warming 14,600 years ago A model-based interpretation of low frequency changes in the carbon cycle during the last 120 000 years and its implications for the reconstruction of atmospheric Δ14C Temperature reconstruction from 10 to 120 kyr b2k from the NGRIP ice core Long-term carbon sequestration in North American peatlands Late Quaternary atmospheric CH4 isotope record suggests marine clathrates are stable Changing boreal methane sources and constant biomass burning during the last termination Independent variations of CH4 emissions and isotopic composition over the past 160,000 years Contribution of permafrost soils to the global carbon budget LGM permafrost distribution: how well can the latest PMIP multi-model ensembles reconstruct The Last Permafrost Maximum (LPM) map of the Northern Hemisphere: permafrost extent and mean annual air temperatures Permafrost carbon-climate feedbacks accelerate global warming Expert assessment of vulnerability of permafrost carbon to climate change 14CH4 measurements in Greenland ice: investigating last glacial termination CH4 sources Hydrological changes in eastern Europe during the last 40,000 years inferred from biomarkers in Black Sea sediments Millennial-scale variability in Antarctic ice-sheet discharge during the last deglaciation Sea-level fingerprinting as a direct test for the source of global meltwater pulse IA Global sea floor topography from satellite altimetry and ship depth soundings The deep permafrost carbon pool of the Yedoma region in Siberia and Alaska Onset of deglacial warming in West Antarctica driven by local orbital forcing Atmospheric CO2 and climate on millennial time scales during the last glacial period Different ocean states and transient characteristic in Last Glacial Maximum simulations and implications for deglaciation Antarctic climate signature in the Greenland ice core record Changes in atmospheric CO2 and its carbon isotopic ratio during the penultimate deglaciation A reconstrution of atmospheric carbon dioxide and its stable carbon isotopic composition from the penultimate glacial maximum to the last glacial inception Abrupt change of Antarctic moisture origin at the end of Termination II Antarctic temperature and global climate during Termination II Expression of the bipolar see-saw in Antarctic climate records during the last deglaciation Regional imprints of millennial variability during the MIS 3 period around Antarctica Vulnerability of permafrost carbon to global warming Part II: sensitivity of permafrost carbon stock to global warming Solar modulation of cosmogenic nuclide production over the last millennium: comparison between 14C and 10Be records The role of ocean transport in the uptake of anthropogenic CO2 Constraint of the CO2 rise by new atmospheric carbon isotopic measurements during the last deglaciation One-to-one coupling of glacial climate variability in Greenland and Antarctica Download references Fischer for some insights on CH4 in ice cores and T Muscheler calculated GISP2 10Be fluxes and provided all GISP2 10Be data on the GICC05 age scale Ridgwell provided helpful comments and GENIE model results used for carbon cycle model evaluation Saito provided PMIP3 result on LGM permafrost distribution Mudelsee helped with the application of the Breakfit software is supported by the European Community (Project Past for Future) and by the Agence Nationale de la Recherche (Project EQUIPEX ASTER-CEREGE) Alfred-Wegener-Institut Helmholtz-Zentrum für Polar-und Meeresforschung (AWI) performed carbon cycle simulations with BICYCLE; E.B performed carbon cycle simulations with other box models; G.K drafted the manuscript with contributions from all co-authors Supplementary Notes 1-3 and Supplementary References (PDF 583 kb) Download citation Communications Earth & Environment (2023) Communications Earth & Environment (2022) Sign up for the Nature Briefing: Microbiology newsletter — what matters in microbiology research Metrics details Changes in the Arctic climate-ocean system can rapidly impact carbon cycling and cryosphere Methane release from the seafloor has been widespread in the Barents Sea since the last deglaciation being closely linked to changes in pressure and bottom water temperature we present a post-glacial bottom water temperature record (18,000–0 years before present) based on Mg/Ca in benthic foraminifera from an area where methane seepage occurs and proximal to a former Arctic ice-sheet grounding zone Coupled ice sheet-hydrate stability modeling shows that phases of extreme bottom water temperature up to 6 °C and associated with inflow of Atlantic Water repeatedly destabilized subsurface hydrates facilitating the release of greenhouse gasses from the seabed these warming events played an important role in triggering multiple collapses of the marine-based Svalbard-Barents Sea Ice Sheet Future warming of the Atlantic Water could lead to widespread disappearance of gas hydrates and melting of the remaining marine-terminating glaciers if escaping to the atmosphere could lead to further warming WSC: West Spitsbergen Current; ESC: East Spitsbergen Current The latter method quantifies BWT as an average of the whole foraminiferal assemblage and might therefore be biased towards species-specific ecological preferences other than temperature (e.g. we quantify BWT based on Mg/Ca in the benthic foraminiferal species Cassidulina neoteretis in order to more accurately constrain past temperature changes in the western Barents Sea the reconstructed BWT is used to investigate the past dynamic of the gas hydrate stability zone (GHSZ) by modeling variations in its thickness to provide an oceanographically constrained history of methane-venting from the northwestern Barents Sea area A Weight percentages of the different grain-size fractions. B Magnetic susceptibility. C Reconstructed bottom water temperature (BWT). D Age-depth model. Left columns: XRF-Image scan, X-ray images, and lithological log with cal ages indicated of core 1059. Ages in italics are transferred ages from two nearby cores (see text for explanation). LG: Late Glacial; HS1: Heinrich Stadial 1; BA: Bølling-Allerød interstadials; YD: Younger Dryas stadial the BWT stabilized with an average of 3.3 ± 1 °C except for a short warming event of around 6000 years the thickness of the GHSZ presented in this work should be considered as a narrowest limit (see “Methods” section) Based on our correlation and placing core 920 into our age model (see “Methods” section) increased release of gas occurs in the late HS1 during the Bølling interstadial and Allerød interstadial Records of past BWT at different time scales underline the risk that the current “Altantification” process in the Arctic bears in triggering an increase in seepage of methane into the ocean causing an increase in ocean acidification and potentially amplifying the effects of current climate change if reaching the atmosphere Core HH18-1059GC (core 1059) (76°06.117′N; 15°58.077′E, 382 m water depth) was retrieved from the southwestern Barents Sea during a cruise in July 2018 with R/V Helmer Hanssen (Fig. 1) The 4.15 m long core was split into 1-m sections the core sections were X-rayed and logged with a GEOTEK 7.9 Multi-Sensor Logger The core was split longitudinally into two halves The work half was color imaged with a Jai L-107CC 3 CCD RGB line scan camera installed on an Avaatech XRF The archive half was scanned at 10 and 30 kV on an Avaatech XRF for bulk element ratios the work half was sampled in 1-cm thick slices Samples were selected following the main focus of our study: (a) from 3.9 to 2.9 m samples were selected every 2 cm except at 3.66–3.64 m and 3.83–3.80 m where every cm was selected; (b) from 2.9 to 0.1 m samples were selected every 10 cm; (c) from 0.1 to 0 m weighed and the weight percent of each grain size was calculated The lithological log is based on visual examination, together with the records of X-ray scanning, grain-size distribution, and magnetic susceptibility (Fig. 2) Oxygen and carbon isotopes were analyzed on pristine tests of the planktic foraminiferal species Neogloboquadrina pachyderma and on the benthic foraminiferal species Cassidulina neoteretis The measurements were performed on 10 to 20 specimens (only 8 samples out of 117 samples contained less than 10 specimens) of each species using a Thermo Scientific MAT253 IRMS and Gasbench II at the Department of Geosciences The precision of the instrument is 0.1‰ for oxygen and carbon isotopes and the results are reported versus the in-house Vienna Pee Dee Belemnite standard concluded that core 1059 was suitable for benthic foraminiferal Mg/Ca-based reconstructions of BWT the analytical error (±0.017 mmol/mol equivalent to 0.18 °C using Kristjánsdóttir et al.’s calibration) and the standard deviation of the replicates of four samples (±0.078 mmol/mol equivalent to 0.78 °C) were used to calculate the error that is the result of the squared root of the sum of the squared individual errors The analytical error was calculated as two times the mean standard deviation of the repeated measurements on the in-house standard solution This gave an estimated propagation error of ±1.01 °C for C When an average BWT was presented in the main text the error was calculated taking into account the propagation error of the measurement (±1.01 °C) and the standard deviation of the mean our BWT would represent seasons of AW inflow (i.e. with one radiocarbon date and three tie-points to other cores in the region In order to allow a direct comparison between core 920 and our core 1059 a new and improved age-depth model of core 920 was established using our much more detailed chronology The data is stored at the UiT Open Research Data Repository: https://doi.org/10.18710/XFYDFL Mechanisms underlying recent arctic atlantification Modeling the fate of methane hydrates under global warming Temporal constraints on hydrate-controlled methane seepage off Svalbard Reduced methane seepage from Arctic sediments during cold bottom-water conditions The anaerobic oxidation of methane: new insights in microbial ecology and biogeochemistry et al.) 457–477 (Springer Berlin Heidelberg Fate of rising methane bubbles in stratified waters: How much methane reaches the atmosphere Seafloor oxygen consumption fuelled by methane from cold seeps Rising Arctic Ocean temperatures cause gas hydrate destabilization and ocean acidification The role of the North Atlantic Drift in the millennial timescale glacial climate fluctuations Persistent intermediate water warming during cold stadials in the southeastern Nordic seas during the past 65 k.y El bani Altuna, N., Ezat, M. M., Greaves, M. & Rasmussen, T. L. Millennial‐scale changes in bottom water temperature and water mass exchange through the Fram Strait 79 °N, 63–13 ka. Paleoceanogr. Paleoclimatol. https://doi.org/10.1029/2020PA004061 (2021) Iceberg discharges into the north atlantic on millennial time scales during the last glaciation The last Eurasian ice sheets-a chronological database and time-slice reconstruction Paleoceanographic evolution of the SW Svalbard margin (76 °N) since 20,000 14C yr BP Climate and ocean forcing of ice-sheet dynamics along the Svalbard-Barents Sea ice sheet during the deglaciation ∼20,000–10,000 years BP Ocean-driven millennial-scale variability of the Eurasian ice sheet during the last glacial period simulated with a hybrid ice-sheet–shelf model Rapid submarine ice melting in the grounding zones of ice shelves in West Antarctica North Atlantic warming and the retreat of Greenland’s outlet glaciers Postglacial response of Arctic Ocean gas hydrates to climatic amelioration A stratigraphic framework for abrupt climatic changes during the Last Glacial period based on three synchronized Greenland ice-core records: refining and extending the INTIMATE event stratigraphy Multi-proxy approach to unravel methane emission history of an Arctic cold seep Geological controls on fluid flow and gas hydrate pingo development on the Barents Sea margin Distribution of modern benthic foraminifera from fjords of Svalbard Seasonal dynamics of benthic foraminifera in a glacially fed fjord of Svalbard Eurasian Ice Sheet collapse was a major source of Meltwater Pulse 1A 14,600 years ago Brine formation in relation to climate changes and ice retreat during the last 15,000 years in Storfjorden Timescales of methane seepage on the Norwegian margin following collapse of the Scandinavian Ice Sheet Dynamic and history of methane seepage in the SW Barents Sea: new insights from Leirdjupet Fault Complex Seabed morphology and shallow sedimentary structure of the Storfjorden and Kveithola trough-mouth fans (North West Barents Sea) Ice‐margin retreat and grounding‐zone dynamics during initial deglaciation of the Storfjordrenna Ice Stream Reconstruction of ice sheet retreat after the Last Glacial maximum in Storfjorden Massive blow-out craters formed by hydrate-controlled methane expulsion from the Arctic seafloor Ice stream retreat dynamics inferred from an assemblage of landforms in the northern Barents Sea Sea-ice dynamics in an Arctic coastal polynya during the past 6500 years The history and future trends of ocean warming‐induced gas hydrate dissociation in the SW Barents Sea RCP 8.5—A scenario of comparatively high greenhouse gas emissions An overview of CMIP5 and the experiment design Vadakkepuliyambatta, S. et al. Climatic impact of Arctic Ocean methane hydrate dissociation in the 21st-century. Earth Syst. Dynam. Discuss. 1–27 https://doi.org/10.5194/esd-2017-110 (2017) Ocean temperature variability for the past 60 years on the Norwegian-Svalbard margin influences gas hydrate stability on human time scales Marine20–The marine radiocarbon age calibration curve (0–55,000 cal BP) Methods and code for ‘classical’ age-modelling of radiocarbon sequences Flexible paleoclimate age-depth models using an autoregressive gamma process The influence of microhabitats on the carbon isotopic composition of deep-sea benthic foraminifera Comparison of Atlantic and Pacific paleochemical records for the last 215,000 years: changes in deep ocean circulation and chemical inventories Identification and removal of Mn-Mg-rich contaminant phases on foraminiferal tests: Implications for Mg/Ca past temperature reconstructions Reconstruction of hydrographic changes in the southern Norwegian Sea during the past 135 kyr and the impact of different foraminiferal Mg/Ca cleaning protocols An intensity ratio calibration method for the accurate determination of Mg/Ca and Sr/Ca of marine carbonates by ICP-AES New spatial Mg/Ca-temperature calibrations for three Arctic benthic foraminifera and reconstruction of north Iceland shelf temperature for the past 4000 years Freshwater and Atlantic water inflows to the deep northern Barents and Kara seas since ca 13 14C ka: foraminifera and stable isotopes Thermal evolution of the western Svalbard margin Recent changes to the Gulf Stream causing widespread gas hydrate destabilization Rapid coupling between ice volume and polar temperature over the past 150,000 years A 60 000 year Greenland stratigraphic ice core chronology Download references We thank the captain and crew of RV Helmer Hansen and the participants of cruise CAGE18-3 for their assistance in the core retrieval Anne Paavilainen is warmly thanked for her assistance in the core sampling We are grateful to Matteus Lindgren (Department of Geosciences UiT–The Arctic University of Norway) who performed stable isotope measurements We also thank Wei-Li Hong for providing us with the XRF data from core CAGE 15-2 920GC Henry Patton is thanked for his help with the English language and constructive comments on an earlier version of this manuscript This research was funded by the Research Council of Norway through its Centers of the Excellence funding scheme is funded by the Research Council of Norway and the Co-funding of Regional and International Programmes (COFUND)–Marie Skłodowska-Curie Actions under the EU Seventh Framework Programme (FP7) Naima El bani Altuna, Tine Lander Rasmussen, Mohamed Mahmoud Ezat & Sunil Vadakkepuliyambatta Helmholtz Center for Polar and Marine Research MARUM‐Center for Marine Environmental Sciences Godwin Laboratory for Palaeoclimate Research performed the study and data acquisition with supervision from M.M.E Transient hydrate stability modeling was performed by S.V All authors contributed to the discussion of results and writing of the manuscript Peer review information Communications Earth & Environment thanks Maria De La Fuente Ruiz reviewer(s) for their contribution to the peer review of this work Download citation DOI: https://doi.org/10.1038/s43247-021-00264-x A woolly brown rhinoceros that weighed two tons once roamed northeastern Siberia before mysteriously disappearing around 14,000 years ago A new study by a Swedish and Russian team of scientists who examined DNA fragments from the remains of 14 of these prehistoric mammals lets our species off the hook They say the population of the animal - also known by its scientific name Coelodonta antiquitatis - remained stable for millennia as they lived alongside humans before dropping sharply toward the end of the last ice age "That makes it more likely that climatic changes that happened around 14,000 years ago are the primary driver of extinction a geneticist at Sweden's Centre for Palaeogenetics Dalen led the study that was published in the journal Current Biology on Thursday How did they reach that conclusion from DNA strands taken from the remains of animals frozen in the soil for thousands of years The size of a population of a species is proportional to its level of genetic diversity and the degree of inbreeding The team were able to analyze the complete genome of one rhinoceros dating from 18,500 years ago By comparing the chromosomes inherited from the mother and from the father they determined inbreeding was low and diversity was high "One individual's genome is a mosaic of all its ancestors," explained Dalen and its ancestors must also have belonged to a large population" going back tens of thousands of years From other animals they were able to harvest mitochondrial genomes - which are passed down from the mother - and from this could estimate the size of the female populations over time Humans arrived in this part of Siberia 30,000 years ago. Though they hunted the rhinos, the animal's population remained steady for 12,000 more years until an abrupt period of warming known as the Bolling-Allerod The same team previously published the genome of another megaherbivore, the woolly mammoth - and believe this species likewise went extinct due to climate change Their conclusions are still being debated among the scientific community A key difference is that the mammoths went extinct twice: the ones on mainland Siberia disappeared around the same time as the rhinos but a few hundred survived on Wrangel Island six millennia longer Today, the closest living relative of the woolly rhino is the Sumatran rhino. Frequently poached and facing the destruction of their habitat, there are fewer than 80 left in existence Here, no one can argue that humans are free of blame © Agence France-Presse Metrics details The periodic input of meltwater into the ocean from a retreating Laurentide Ice Sheet is often hypothesized to have weakened the Atlantic meridional overturning circulation (AMOC) and triggered several cold periods during the last deglaciation (21,000 to 8,000 years before present) we use a numerical model to investigate whether the Intra-Allerød Cold Period was triggered by the drainage of Glacial Lake Iroquois Performing a large suite of experiments with various combinations of single and successive short (1 month) and long (1 year) duration flood events we were unable to find any significant weakening of the AMOC This result suggests that although the Hudson Valley floods occurred close to the beginning of the Intra-Allerød Cold Period Our results have implications for re-evaluating the relationship of meltwater flood events (past and future) to periods of climatic cooling particularly with regards to flood input location Topography and bathymetric imagery and data from the General Bathymetric Chart of the Oceans and Map Data © 2019 Google the mean annual AMOC anomalies of the Control with no background meltwater flux scenario (black line) are also shown yet there is still no reduction in AMOC strength similar to that expected for this particular large-scale cooling event we were again not able to find a prolonged weakening in the overturning cell in any of our experiments releasing either single or multiple outburst floods on top of this background flux that suggest a threshold in the climate system capable of causing the prolonged IACP cooling had occurred We thus speculate that background drainage from other LIS outlets might have played an additional role in further “pre-conditioning” the overturning cell so that smaller floods emanating from the Hudson Valley may have been sufficient to significantly weaken AMOC our results indicate that meltwater emanating solely from the Hudson Valley ~13,300 BP (in the form of either outburst floods or persistent drainage from the LIS) is unlikely to have been the main cause of the cooling associated with the IACP Even in the most extreme scenario (which likely far exceeds the actual flood events at this time) the meltwater events appear either too small or originate too far south of regions of NADW formation to impact AMOC and trigger the IACP uncoupled atmosphere in our simulations leaves out this potential “pre-conditioning” mechanism but allows us to test whether or not the Hudson Valley floods could have been responsible for significant AMOC weakening and instigation of the IACP Having established the unlikely nature of the Hudson Valley floods as the sole driver of a weakened AMOC future experiments can explore the interactions between competing mechanisms and potential AMOC and climate responses this study highlights the importance of the geographical location of any meltwater input on the potential to alter large-scale ocean circulation and climate future model studies should be aimed at exploring the spatial and temporal interactions of multiple meltwater/freshwater sources on AMOC as well as the role of other associated and linked climate mechanisms The model code (MITgcm) utilized to perform all of the experiments and generate the figures is publicly available from mitgcm.org Routing of meltwater from the Laurentide Ice Sheet during the Younger Dryas cold episode A systematic study of the impact of freshwater pulses with respect to different geographical locations Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE Future climate response to Antarctic Ice Sheet melt caused by anthropogenic warming Catastrophic meltwater discharge down the Hudson Valley: a potential trigger for the Intra-Allerød cold period A stratigraphic framework for abrupt climatic changes during the Last Glacial period based on three synchronized Greenland ice-core records: Refining and extending the INTIMATE event stratigraphy Drainage of late Wisconsin glacial lakes and the morphology and late quaternary stratigraphy of the New Jersey-southern New England continental shelf and slope Late Wisconsinan meltwater floods through the Champlain and Hudson Valleys Post valley heads deglaciation of the Adirondack Mountains and adjacent lowlands Deglaciation of the Champlain Valley New York and Vermont and its possible effects on North Atlantic climate change Regional beryllium-10 production rate calibration for late-glacial northeastern North America Ventilation history of Nordic Seas overflows during the last (de)glacial period revealed by species-specific benthic foraminiferal 14C dates North Atlantic intermediate water variability over the past 20,000 years A catastrophic meltwater flood event and the formation of the Hudson Shelf Valley studies of the ocean on parallel computers In Mechanisms of Global Climate Change at Millennial Time Scales (eds Clark Atlantic meridional overturning circulation: observed transport and variability Large sensitivity to freshwater forcing location in 8.2ka simulations Response of the Atlantic Ocean circulation to Greenland Ice Sheet melting in a strongly-eddying ocean model North Atlantic climate response to lake Agassiz drainage at coarse and ocean eddy-permitting resolutions Freshwater outbursts to the oceans from glacial Lake Agassiz and their role in climate change during the last deglaciation Investigating the causes of the response of the thermohaline circulation to past and future climate changes Freshwater forcing of abrupt climate change during the last glaciation Model support for forcing of the 8.2 ka event by meltwater from the Hudson Bay ice dome The 8.2 ka cooling event caused by Laurentide ice saddle collapse Impact of floods versus routing events on the thermohaline circulation Dependence of abrupt atlantic meridional ocean circulation changes on climate background states Abrupt glacial climate shifts controlled by ice sheet changes Arctic sea ice export as a driver of deglacial climate Centennial-scale climate change from decadally-paced explosive volcanism: A coupled sea ice-ocean mechanism Miller, G. H. et al. Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks. Geophys. Res. Lett., 39, 1–5, L02708. https://doi.org/10.1029/2011GL050168 (2012) Consequences of future increased Arctic runoff on Arctic Ocean stratification Response of the North Atlantic dynamic sea level and circulation to Greenland meltwater and climate change in an eddy-permitting ocean model Part 1: effects of different solver implementations and parameterizations Onshore record of Hudson River drainage to the continental shelf from the late Miocene through the late Wisconsinan deglaciation The international thermodynamic equation of seawater – 2010: calculation and use of thermodynamic properties Intergovernmental Oceanographic Commission Late quaternary reconstruction of Lake Iroquois in the Ontario basin of New York Download references This study was supported by the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution All numerical simulations were performed on the High-Performance Computing (HPC) machine The authors thank two reviewers whose comments and suggestions greatly improved this manuscript performed and analyzed the meltwater flood simulation experiments helped with running the numerical simulations and aided in the analysis of the model output and data interpretation contributed to the original conceptualization of the study along with S.P wrote the manuscript and designed figures/tables with input and contributions from all authors Peer review information Communications Earth & Environment thanks Pepijn Bakker and the other Download citation DOI: https://doi.org/10.1038/s43247-021-00228-1 Sign up for the Nature Briefing: Anthropocene newsletter — what matters in anthropocene research Metrics details During the last deglaciation substantial volumes of meltwater from the decaying Laurentide Ice Sheet were supplied to the Arctic Gulf of Mexico and North Atlantic along different drainage routes These events are suggested to have impacted global climate for example initiating the Younger Dryas cold period Here we analyze the authigenic Pb isotopic composition of sediments in front of the Arctic Mackenzie Delta a sensitive tracer for elevated freshwater runoff of the retreating Laurentide Ice Sheet Our data reveal continuous meltwater supply to the Arctic along the Mackenzie River since the onset of the Bølling–Allerød The strongest Lake Agassiz outflow event is observed at the end of the Bølling–Allerød close to the onset of the Younger Dryas In context of deglacial North American runoff records from the southern and eastern outlets our findings provide a detailed reconstruction of the deglacial drainage chronology of the disintegrating Laurentide Ice Sheet Compared to terrestrial archives marine proxies are less sensitive to even small changes in freshwater runoff and weathering regime but often preserve continuous and well dated information about the most extreme events which are often the most important triggers for climatic perturbations The red frame highlights the area displayed at expanded scale in panel b b Detailed map of the Mackenzie Delta region Core sites investigated in this study are displayed as red circles The blue line indicates the Mackenzie River in its modern bed The flow direction and position of the Shelfbreak Current and Beaufort Gyre are indicated by arrows (light blue and brown Light yellow areas indicate major Lake Agassiz drainage events through the Mackenzie River Site JPC-15/27 was only partially influenced by material arriving from the Amundsen Gulf explaining the different isotopic signatures of Site JPC-15/27 and JPC-19 sediments equally marks this abrupt and persistent shift in provenance although the amplitude of this variation is much smaller and not as obvious as the previous provenance shift described above The influence of Amundsen Gulf sediments on JPC-15/27 decreased again towards the end of the Bølling–Allerød marked by slightly less radiogenic values the exposure time of sedimentary substrate (e.g glacial flour) to weathering and subglacial supply of meltwater has to be taken into account the Pb isotopic composition of Lake Agassiz lake water must have been modified continuously in the course of the deglaciation but have to be confirmed in future analysis of Lake Agassiz sedimentary sequences the isotopic signature of each water drainage event from Lake Agassiz is expected to be modified differently during transport toward the Arctic depending on the above mentioned conditions as well as the time and distance of transport The collapse of the Hudson Bay Ice Saddle and the drainage of Lake Agassiz might have caused further instabilities and breakup of the LIS that have caused re-routing of meltwater from northern glacial Lakes which was previously directed to the Arctic Ocean now to the former Lake Agassiz area and the Hudson Bay Such a sequence of events would have the capability of terminating extensive freshwater supply from the southern Mackenzie catchment into the Arctic Ocean the early Holocene Mackenzie drainage area was established and sediment supply similar to today towards the Arctic Ocean was manifested within this area The same event at 8.5 ka BP was also recorded in the authigenic isotopic signature at this point resulting in a return to remarkably invariant Holocene unradiogenic values and a shift in the ARM30mT/ARM0mT ratio The change towards less radiogenic authigenic Pb isotope compositions not only marks the onset of uniform sedimentation detached from glacial processes inland after 8.5 ka BP but the more radiogenic Pb isotope compositions before that time bear evidence for the very dynamic runoff environment with an occasionally more or less pronounced contribution from glacial lakes c Chart displays the major active drainage routes and their potential freshwater source Northern glacial lakes (NGL) are Lake Mackenzie and Lake McConnell; Southeastern Glacial Lakes (SEGL) represent former glacial lakes in the Great Lakes area as well as glacial Lake Ojibway meltwater from the LIS was routed nearly exclusively along the St Lawrence valley into the North Atlantic as well as along the Mackenzie River into the Arctic Ocean While Lake Agassiz continuously supplied freshwater through the St two potential overflow events into the Arctic Ocean took place at 12.0 and 11 the Mackenzie Pb isotope record of JPC-15/27 documents continuous northward directed meltwater routing into the Arctic Ocean from the northern side of the LIS since the onset of the Bølling–Allerød lasting almost until the final disintegration stages of the Laurentide Ice Sheet around 8.5 ka BP Our data solve the long-standing conundrum surrounding the activity of a northwestern drainage route of Lake Agassiz into the Arctic Ocean at the onset of the Younger Dryas The authigenic Pb isotope records present direct evidence of freshwater routing from Lake Agassiz along the Mackenzie valley at the very end of the Bølling–Allerød and therefore support the hypothesis of a freshening Arctic Ocean as a potential trigger for the Younger Dryas cooling Our northwestern drainage chronology of Lake Agassiz since the Younger Dryas provides insights into the melting chronology of the LIS and its runoff along the southern and eastern drainage routes the role of the eastern drainage route along the St Lawrence valley as well as into the Labrador Sea should be investigated in greater detail to better constrain its importance as outlet routes of Lake Agassiz freshwater during the Younger Dryas elemental concentrations of major elements (Li Th and U) were measured for the extracted authigenic phase and the digested detrital samples with an Agilent Series 7500 ICP-MS at GEOMAR Kiel The relative reproducibility of element measurements is better than 2% (2SD) based on repeated determination of the elemental composition of the secondary standard USGS NOD-A-1 which in turn can be a function of changes in sediment source erosion/weathering and hydrological regimes Magnetic Susceptibility and the ARM30mT/ARM0mT ratio can provide additional insights to disentangling the effects of changing particle size or sediment source along with sedimentological and geochemical data Data of this study can be accessed through the Pangaea data repository (https://doi.org/10.1594/PANGAEA.932646) Megaflooding associated with glacial Lake Agassiz Dynamics of the Laurentide ice sheet during the last deglaciation: evidence from the Gulf of Mexico Phasing of deglacial warming and Laurentide Ice Sheet meltwater in the Gulf of Mexico Geochemical proxies of North American freshwater routing during the Younger Dryas cold event Deglaciation ages and meltwater routing in the Fort McMurray region northeastern Alberta and northwestern Saskatchewan Alternative routing of Lake Agassiz overflow during the Younger Dryas: new dates A review and analysis of varve thickness records from glacial Lake Ojibway (Ontario and Quebec Arctic freshwater forcing of the Younger Dryas cold reversal Identification of Younger Dryas outburst flood path from Lake Agassiz to the Arctic Ocean The Tintah-Campbell gap and implications for glacial Lake Agassiz drainage during the Younger Dryas cold interval Routing of meltwater from the Laurentide Ice Changes in the bathymetry and volume of glacial Lake Agassiz between 11,000 and 9300 14C yr B.P Glacial Lake Agassiz: a 5000 yr history of change and its relationship to the δ18O record of Greenland Radiocarbon deglaciation chronology of the Thunder Bay Ontario area and implications for ice sheet retreat patterns An updated radiocarbon-based ice margin chronology for the last deglaciation of the North American Ice Sheet Complex Two possible routings for overflow from Lake Agassiz during the Younger Dryas Loope on ‘Alternative routing of Lake Agassiz overflow during the Younger Dryas: new dates Age of Gimli beach of Lake Agassiz based on new OSL dating Authigenic Pb isotopes from the Laurentian Fan: changes in chemical weathering and patterns of North American freshwater runoff during the last deglaciation Multiple meltwater discharge and ice rafting events recorded in the deglacial sediments along the Beaufort Margin Laurentide ice sheet meltwater recorded in gulf of Mexico deep-sea cores Retreat of the Laurentide ice sheet tracked by the isotopic composition of Pb in western North Atlantic seawater during termination 1 The release of Pb and REE from granitoids by the dissolution of accessory phases Experimental evidence for mineral-controlled release of radiogenic Nd Hf and Pb isotopes from granitic rocks during progressive chemical weathering Weathering versus circulation controlled changes in radiogenic isotope tracer composition of the Labrador Sea and North Atlantic Deep Water Collapse of a marine-based ice stream during the early Younger Dryas chronozone Arctic ice export events and their potential impact on global climate during the late Pleistocene Wheeler, J. O. et al. Geological map of Canada/Carte géologique du Canada. Geological Survey of Canada, Map 1860A https://doi.org/10.4095/208175 (1996) Late glacial drainage systems along the northwestern margin of the Laurentide Ice Sheet Duk-Rodkin, A. & Lemmen, D. S. Glacial history of the Mackenzie region. Bull. Geol. Surv. Canada 11–20 https://doi.org/10.4095/211903 (2001) Major changes in ice stream dynamics during deglaciation of the north-western margin of the Laurentide Ice Sheet Leveraging the rapid retreat of the Amundsen Gulf Ice Stream 13,000 years ago to reveal insight into North American Deglaciation and magnetic signatures of surface sediments from the Canadian Beaufort Shelf and Amundsen Gulf (Canadian Arctic) Opening of glacial Lake Agassiz’s eastern outlets by the start of the Younger Dryas cold period Preboreal oscillation caused by a glacial Lake Agassiz flood Sources of Labrador Sea sediments since the last glacial maximum inferred from Nd-Pb isotopes Freshwater routing by the Laurentide Ice Sheet during the last deglaciation In Mechanisms of Global Climate Change at Millennial Time Scales Early stage weathering systematics of Pb and Nd isotopes derived from a high-Alpine Holocene lake sediment record Sedimentary record of glacial Lake Mackenzie Canada: implications for Arctic freshwater forcing Labrador Sea freshening at 8.5 ka BP caused by Hudson Bay Ice Saddle collapse Assessing the ages of the Moorhead and Emerson phases of glacial Lake Agassiz and their temporal connection to the Younger Dryas cold reversal Proglacial lakes and the southern margin of the Laurentide Ice Sheet In North America and Adjacent Oceans During the Last Deglaciation 39–69 (The Geological Society of America Enhanced sea-ice export from the Arctic during the Younger Dryas Reduced meltwater outflow from the Laurentide ice margin during the Younger Dryas Forcing of the cold event of 8,200 years ago by catastrophic drainage of Laurentide lakes Linking the 8.2 ka event and its freshwater forcing in the Labrador Sea The 8.2 ka cooling event caused by Laurentide ice saddle collapse Lake Agassiz drainage bracketed Holocene Hudson Bay Ice Saddle collapse Radiocarbon measurements of small-size foraminiferal samples with the mini carbon dating system (MICADAS) at the University of bern: implications for paleoclimate reconstructions Stuvier, M., Reimer, P. J. & Reimer, R. W. CALIB 8.2 (2020) (accessed 2 November 2020) WWW program at http://calib.org Extracting foraminiferal seawater Nd isotope signatures from bulk deep sea sediment by chemical leaching Efficient extraction of past seawater Pb and Nd isotope signatures from Southern Ocean sediments Reliable extraction of a deepwater trace metal isotope signal from Fe–Mn oxyhydroxide coatings of marine sediments Age and isotopic relationships among the angrites Lewis Cliff 86010 and Angra dos Reis High-precision lead isotope ratio measurement by inductively coupled plasma multiple collector mass spectrometry A new variable dispersion double-focusing plasma mass spectrometer with performance illustrated for Pb isotopes A rapid method for magnetic granulometry with applications to environmental studies Magnetic properties of some synthetic sub‐micron magnetites Chapter three magnetic stratigraphy in paleoceanography: reversals Grain size dependent magnetic discrimination of Iceland and South Greenland terrestrial sediments in the northern North Atlantic sediment record Environmental magnetism: principles and applications Download references We like to thank Ellen Roosen from the Woods Hole Oceanographic Institution who approved sampling of the sediment cores and for the excellent guidance and support during sampling we acknowledge the support of Joseph Stoner and the Oregon State University Paleo and Environmental Magnetism Laboratory We thank Ana Kolevica for technical support This project was carried out in the framework of the Emmy-Noether-Programm of the German Research Foundation (DFG) Grant Li1815/4 This manuscript benefited from constructive criticism provided by two anonymous reviewers as well as James Teller Open Access funding enabled and organized by Projekt DEAL GEOMAR Helmholtz Center for Ocean Research Kiel conceived the study and initiated this project in cooperation with F.S carried out the geochemical analytical work for isotope analysis which were performed by M.G were involved in the discussion of the data and contributed to the final version Communications Earth & Environment thanks James Teller and the other Download citation DOI: https://doi.org/10.1038/s43247-022-00428-3 Metrics details the warming trend into the Holocene was sharply interrupted by a reversal to near glacial conditions Climatic causes and ecological consequences of the Younger Dryas (YD) have been extensively studied however proxy archives from the Mediterranean basin capturing this period are scarce and do not provide annual resolution we report a hydroclimatic reconstruction from stable isotopes (δ18O δ13C) in subfossil pines from southern France Growing before and during the transition period into the YD (12 900–12 600 cal BP) Isotopic signature of tree sourcewater (δ18Osw) and estimates of relative air humidity were reconstructed as a proxy for variations in air mass origin and precipitation regime We find a distinct increase in inter-annual variability of sourcewater isotopes (δ18Osw) with three major downturn phases of increasing magnitude beginning at 12 740 cal BP The observed variation most likely results from an amplified intensity of North Atlantic (low δ18Osw) versus Mediterranean (high δ18Osw) precipitation This marked pattern of climate variability is not seen in records from higher latitudes and is likely a consequence of atmospheric circulation oscillations at the margin of the southward moving polar front we assume that this general feature of seasonality was active during the Allerød/YD transition and in particular cold season precipitation and subsequent spring melt provided the water source for the studied trees particularly in consideration of the low sample replication Blue shaded areas highlight periods of extreme sourcewater depletion during the period of enhanced inter-annual variability (Barbiers Change Point This provides further evidence that the transformation to extreme conditions (BCP) occurred within an overall switch to new conditions according to the mean chronology underscoring the importance of high resolution records in reconstructing incremental/progressive change during climate instability and change as seen in the step-wise oscillatory nature of hydroclimate variability in southern France at Barbiers expressed as an enhanced amplitude and frequency of winter storms and extreme events at Barbiers during the onset of a widespread and probably more capricious than previously thought reversal to the near glacial conditions of the YD with a shift of 19 years (12 190 b2k) applied to the data utilized in this study The known dates of Meerfelder Maar tephra isochrones and Barbiers trees permit the estimation of absolute ages allowing a robust connection between the three proxy archives and thus a regional inter-site comparison of climatic events The calculated linear model coefficients of the dendrodata (δ18Ocell tree-ring width) were two orders of magnitude higher (0.674 proving the dual-isotope model output is stable within dating uncertainties These results are logical as δ18Ocel is mainly a measure of local sourcewater variability influenced by stomata conductance (also recorded in δ13Ccell) which is driven by relative humidity and thus temperature (inherent in tree ring widths) Inter-annual δ18Ocell variability (Fig. 2d ∆‰) was calculated by subtracting current year δ18Ocell (‰) from previous year δ18Ocell (‰) to calculate ‰ difference per year of each individual tree These values were then converted to absolute differences and subsequently averaged to produce a mean curve (∆‰) The datasets generated during the current study are available from the corresponding author upon reasonable request The importance of independent chronology in integrating records of past climate change for the 60 e 8 ka INTIMATE time interval Ice core evidence of abrupt climatic change The timing of glacier advances in the northern European Alps based on surface exposure dating with cosmogenic 10Be An abrupt wind shift in western Europe at the onset of the Younger Dryas cold period High-Resolution Greenland Ice Core Data Show AbruptClimate Change Happens in Few Years Wally Was Right: Predictive Ability of the North Atlantic ‘Conveyor Belt’ Hypothesis for Abrupt Climate Change Abrupt increase in Greenland snow accumulation at the end of the Younger Dryas event Late-glacial climate oscillations as recorded in Swiss lake sediments Biogeochemical and micro-facial fingerprints of ecosystem response to rapid Late Glacial climatic changes in varved sediments of Meerfelder Maar (Germany) Late-Glacial climatic changes in Eastern France (Lake Lautrey) from pollen Quantification of biotic responses to rapid climatic changes around the Younger Dryas - A synthesis Multiple causes of the Younger Dryas cold period Climate science: Origins of Atlantic decadal swings Timing and dynamics of the last deglaciation from European and North African δ13C stalagmite profiles-comparison with Chinese and South Hemisphere stalagmites Validation of climate model-inferred regional temperature change for late-glacial Europe lake levels and palaeoclimate at the Last Glacial Maximum Radiocarbon time scale calibration using tree rings Contribution of french subfossil tree-ring chronologies at Barbiers River (Southern French Alps) Isotopic typology of the precipitation in the Western Mediterrenean region at the three different time scales Challenging process to make the Lateglacial tree-ring chronologies from Europe absolute - an inventory Wood 14C dating with AixMICADAS: methods and application to tree-ring sequences from the Younger Dryas event in the southern French Alps New tree-ring evidence for the Late Glacial period from the northern pre-Alps in eastern Switzerland Age-related trends in subfossil tree-ring δ13C data Tree height strongly affects estimates of water-use efficiency responses to climate and CO2 using isotopes Decadally Resolved Lateglacial Radiocarbon Evidence from New Zealand Kauri Applying the dual-isotope conceptual model to interpret physiological trends under uncontrolled conditions Linking Stable Oxygen and Carbon Isotopes with Stomatal Conductance and Photosynthetic Capacity: A Conceptual Model An event stratigraphy for the last termination in the North Atlantic region based on the Greenland ice-core record: a proposal by the INTIMATE group Environmental responses to Lateglacial climatic fluctuations recorded in the sediments of pre-Alpine Lake Mondsee (northeastern Alps) Delayed hydrological response to Greenland cooling at the onset of the Younger Dryas in western Europe High-resolution palynological evidence for vegetation response to the Laacher See eruption from the varved record of Meerfelder Maar (Germany) and other central European records Subdecadal-scale vegetation responses to a previously unknown late-Allerød climate fluctuation and Younger Dryas cooling at Lake Meerfelder Maar (Germany) Variability in the western Mediterranean Sea surface temperature during the last 25,000 years and its connection with the Northern Hemisphere climatic changes Does the trigger for abrupt climate change reside in the ocean or in the atmosphere Subfossil tree deposits in the Middle Durance (southern Alps France): Environmental changes from Allerod to Atlantic Atmospheric radiocarbon for the period 1950–2010 Lateglacial calendar year chronology based on annually laminated sediments from Lake Meerfelder Maar Was the 12.1ka Icelandic Vedde Ash one of a kind Sedimentological proof and dating of the early Holocene volcanic eruption of Ulmener Maar (Vulkaneifel Volcanic ash layers from the Last Glacial Termination in the NGRIP ice core The Late Quaternary tephrostratigraphy of annually laminated sediments from Meerfelder Maar A novel device for batch-wise isolation of??-cellulose from small-amount wholewood samples A guideline for sample preparation in modern tree-ring stable isotope research Normalization of measured stable isotopic compositions to isotope reference scales – a review Model evaluation for reconstructing the oxygen isotopic composition in precipitation from tree ring cellulose over the last century RID E-5394-2010 d13C response surface resolves humidity and temperature Oxygen isotope and palaeotemperature records from six Greenland ice-core stations: Camp Century Isotopic composition of cellulose from aquatic organisms Relationship Between the Oxygen Isotope Ratios of Terrestrial Oxygen and Hydrogen Isotope Ratios in PlantCellulose: Mechanisms and Applications in Stable Isotopes in Ecological Research 124–141 (1989) Fractionnement en oxyge’ne 18 et en deute ́rium entre l’eau et sa vapeur between AD 1610 and 1885 inferred from oxygen and hydrogen isotopic measurements of wood cellulose from trees in different hydrologic settings changepoint: An R Package for Changepoint Analysis Download references This study was funded by the joint German Research Foundation (DFG HE3089/9–1 and KR726/10–1) and Swiss National Foundation (SNF 200021L_157187/1) collaborative project (DACH) ‘Improving Late Glacial European tree-ring chronologies for accurate climate archive dating’ and it is a contribution to the climate initiative REKLIM Topic 8 ‘Abrupt climate change derived from proxy data’ of the Helmholtz Association UB received additional funding from the Czech Republic Grant Agency project no GFZ German Research Centre for Geosciences Section 5.2 Climate Dynamics and Landscape Evolution Mediterranean Institute of Marine and Terrestrial Biodiversity and Ecology Global Change Research Centre and Masaryk University French National Institute for Preventive Archaeological Research Institute for Earth and Environmental Science Stable isotope analysis and interpretation completed by M.P. Sample collection and chronology development by C.M. Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations Download citation DOI: https://doi.org/10.1038/s41598-018-32251-2 Jumbo-Visma rider takes first leader's jersey of the five-stage race beating Jasper Philipsen (Alpecin-Deceuninck) to the line after a messy run-in The 20-year-old Dutchman broke free of his own lead-out man to track Philipsen down the left-hand side of the road before hitting out and outmuscling the Belgian Timothy Dupont (Bingoal Pauwels Sauces WB) claimed the final spot on the podium but it was very much a two-horse race Kooij takes the first yellow jersey of the five-stage race with the main peloton all awarded the same time given the crash occurred within the final 3km The opening stage of the Tour of Denmark took the riders on a largely flat 222.6km journey from Allerød to Køge finishing with three laps of an 11km circuit There was a five-man breakaway made up of: Adrian Banaszek (HRE Mazowsze Serce Polski) and Sebastian Nielsen (Restaurant Saru-Carl Ras) with Egan Bernal (Ineos Grenadiers) among those to police the gap from the peloton on his return to racing after his life-threatening crash eight months go Lunder fell away from the breakaway on the first of the local laps The remaining four reached the end of the first lap with a lead of just over 30 seconds with Pedersen attacking to be the last survivor caught just beyond the line as the bell sounded for the final lap and Alpecin-Deceuninck and DSM combined before Jumbo-Visma hit the front with 4km to go QuickStep-AlphaVinyl were nowhere to be seen until the 2km to go mark when they swarmed to the front en masse to take the lead through that left-hander with 1,500m to go but two went down as a pile-up left a sizeable chunk of the bunch stranded QuickStep rolled on and they got to their last lead-out man but Vernon had become detached from his wheel The rider who was on Mørkøv's wheel was in fact Christophe Laporte who in turn opened the taps thinking he was leading out Kooij But the young Dutchman had himself lost Laporte and decided to latch onto Philipsen on the left-hand side taking his slipstream as the Belgian opened up Philipsen launched a powerful sprint but Kooij hit the wind and gradually gained and gained Philipsen launched a desperate bike throw but Kooij already had it wrapped up Results powered by FirstCycling Patrick FletcherSocial Links NavigationPatrick is a freelance sports writer and editor He’s an NCTJ-accredited journalist with a bachelor’s degree in modern languages (French and Spanish) Patrick worked full-time at Cyclingnews for eight years between 2015 and 2023 The Atlantic Ocean at mid-depths may have given out early warning signals Scientists had previously known that at the end of the last Ice Age major changes occurred to the Atlantic Ocean in a period known as the Bolling-Allerod interval the currents of the Atlantic Ocean at its deepest levels changed direction The researchers have analysed the chemistry of 24 ancient coral fossils from the North Atlantic Ocean to learn more about the circulation of its waters during the last Ice Age They found that the corals recorded a high variability in the currents of the Atlantic Ocean at mid-depths up to 1,000 years prior to the Bolling-Allerod interval The team suggests that these changes may have been an early warning signal that the world was poised to switch from its glacial state to the warmer world we know today and that the changes happened first at mid-depths published today in the journal Paleoceanography was carried out by researchers from Imperial College London in conjunction with academics from the Scottish Marine Institute the University of Bristol and Caltech Division of Geology and Planetary Sciences from the Department of Earth Science and Engineering at Imperial College London said: “The world’s oceans have always been an important barometer when it comes to changes in our planet the coral fossils we’ve studied are showing us that the North Atlantic Ocean at mid-depths was undergoing changes up to 1,000 years earlier than we had expected The tantalising prospect is that this high variability may have been a signal that the last Ice Age was about to end.” The fossil corals analysed by the team come from a species called Desmophyllum dianthus which are often around 5cm in diameter and look like budding flowers giving the team a rare insight into what was happening to the ocean’s currents during this relatively brief time Thousands of years ago they grew on the New England Seamounts which are a chain of undersea mountains approximately 1000km off the east coast of the US located at mid-depths 2km beneath the surface This underwater area is important for understanding the North Atlantic’s currents While some of the corals analysed by the team come from historical collections most have been collected by researchers from previous expeditions in 2003 and 2005 to the New England Seamounts The researchers used deep sea robotic submergence vehicles called Hercules and Alvin to collect the ancient coral fossils These ancient coral fossils accumulated rare earth elements from seawater which leached from rocks on land into the Atlantic Ocean and circulated in its currents eventually ending up in the coral skeletons Neodymium isotopes in different regions of the world have specific signatures created by radioactive decay over billions of years The scientists studied the chemistry of the coral fossils to determine where the neodymium isotopes had come from giving them a glimpse into the circulation of the Atlantic Ocean at the end of the Ice Age.  Since the world’s oceans are connected by currents the next step will see the team integrating the evidence they gathered from the North Atlantic Ocean into a picture of global changes in the mid-depths of oceans around the world the team is interested in exploring how the Southern Ocean around Antarctica changed around the same time by analysing neodymium isotopes in a collection of Southern Ocean corals See the press release of this article Article text (excluding photos or graphics) available under an Attribution-NonCommercial-ShareAlike Creative Commons license. Photos and graphics subject to third party copyright used with permission or © Imperial College London Your contact details will never be published we are discussing the madness that occurred at the Ft Lauderdale Pro Swim Ledecky’s world record in the 800 free proves that age is seemingly just a number for her but it also makes the Rio 2016 swim she beat out more memorable Marchand has a few areas of improvement to work on if he hopes to return to his Paris form at the World Championships this summer in Singapore October 31st, 2017 Europe, International, News Jonas Lundström joins Sigma Swim from a position as elite coach at Helsingborg Simsällskap  For a number of years Jonas participated as coach at the Swedish national team   Since 2006 he coached swimmers selected for EC International profile substantiates Sigma Swim vision Sigma Swim have great ambitions for the future explaining the search for an international profile – Now perfectly personified via the hire of Jonas Lundström – In Sigma Swim we work with dedication towards qualifying our swimmers for EC   This is why it has been highly important for us that our future elite coach holds international results in his CV chairman of the board in Sigma Swim Birkerød comments  Her colleague chairman of the board of Sigma Swim Allerød we believe we have found the coach that will continue and expand our ambition to be amongst the leading swim clubs in Denmark – and in Scandinavia What is the big secret behind Jonas Lundströms many impressing results – My greatest concern and value as coach is to ensure that my swimmers experience a fundamental joy in swimming extremely important parameters are that the swimmers are persistent and curious to continuously develop their skills About his goals as Sigma Swim coming head coach – One of the goals is obviously that Sigma Swim becomes the leading – most winning senior- and junior level swim club in Denmark Another goal is that Sigma Swim becomes leading in Scandinavia or even Europe and that Sigma Swim holds the leading elite environment in Denmark – and that potential I can definitely see in Sigma Δdocument.getElementById( "ak_js_1" ).setAttribute( "value" Δdocument.getElementById( "ak_js_2" ).setAttribute( "value" More from SwimSwamSee All Subscribe to our newsletter and receive our latest updates! © 2025 Swim Swam Partners, LLC. All rights reserved. Caoimhe GordonMon 1 Jul 2024 at 15:22Engineering consultancy FDT Consulting Engineers and Project Managers has been acquired by Danish firm NIRAS. FDT, which was established in 1991, has offices in Cork and Dublin. It offers process engineering and project management services, as well as compliance support and sustainability initiatives. It works with companies in the food and beverage sectors on the design of product plants. Other clients include businesses in the biosolutions, pharma and life sciences sectors. “It is our ambition at NIRAS to achieve a leading position as expert consultants to the food & beverage, life science, and green fuels industries,” NIRAS executive vice president Thomas B. Olsen said. "With this acquisition, NIRAS and FDT Consulting Engineers and Project Managers Ltd will be able to create growth opportunities driven by scale and expertise.” He added that both companies will be able to grow their offerings, both in Ireland and internationally. FDT and its subsidiary BrewConnect employ around 70 people in Ireland, which will now join NIRAS. "At FDT, we believe that this acquisition marks a pivotal step towards enhancing our global reach and strengthening our service offerings,” FDT managing director John Hanley said. "By integrating NIRAS’s extensive industry expertise and global scale with FDT’s proven track record in process engineering and sustainability, we are poised to deliver unparalleled value to our clients,” he added. This marks the second acquisition by the Danish multinational in the Irish market and brings the total number employed by the group to 120 here. NIRAS also acquired Mayo-based Dolmen Engineering in June 2022. Dolmen Engineering specialised in projects in the pharma and life sciences industries. Following this acquisition, Castlebar is now the location of the headquarters of NIRAS in Ireland. NIRAS, founded in 1956, employs more than 3,000 people in 31 countries. It provides consultancy on more than 7,000 projects in sectors including energy, pharma and life science and green fuels. The group recorded earnings before interest, taxes, and amortisation (Ebita) of DKK 167m (€22.3m) in 2023. Revenues rose to DKK 3.8bn (€510m) last year. Join the Irish Independent WhatsApp channel hardcore Lamborghini Diablo GTR?The hardest car from Lambo before Audi took over has come up for sale This Diablo GTR isn’t just hairy-looking – it’s hairy full stop Being the last scary, uncomfortable Lamborghini before Audi acquired the Italian supercar manufacturer in 1998, this Diablo GTR is the last bastion of old school Lambo lairiness. And now, thanks to Formula Automobile in Allerod number 22 out of the 30-car build run could be yours The GTR was a race-ready track-only version of the mad Diablo GT (although the GT never was road legal in the United States and Japan) and first shown at the 1999 Bologna Motor Show Being the successor to the Diablo SVR (a slicks ‘n’ wings version of the Diablo SV) the GTR was made to race in Lambo’s fighty one-make Supertrophy championship around Europe The 6.0-litre V12 engine is common to all Diablos but this one has been honed to 590 horsepower (over 100 more than the original and 25 more than the GT) through a specially tuned exhaust system without cats So just take a minute and think about how good the raucous sound would be Getting the last drops of go out of the naturally aspirated 12-banger wasn’t easy requiring a multi-throttle intake manifold with an individual intake system dynamic air inlet duct system (upstream of the intake plenum) and titanium connecting rods coupled to a lightened crankshaft the biggest changes were to the chassis frame That monster rear wing that gives lots of downforce goodness is bolted directly to the chassis while the rest of the aero kit is completely new The suspension was modified for racing with both the shock absorbers and anti-roll bars being completely adjustable Brakes were upgraded to full racing Brembos while the Lucas ABS system was still plugged in – good for not locking up into the nearest barrier at 200mph Those gorgeous 18-inch lightweight magnesium wheels with one-bolt central locking mechanism accepted all manner of slicks and a race-grade fuel tank with fast filling system was installed the caverns at the back feed two water radiators in parallel that are side mounted to the engine while an engine oil cooler is up front While all those other additional scoops feed coolers for gearbox and the differential But the roof is made out of steel for torsional rigidity and the doors are aluminium to comply with safety regulations Have you forgotten about all that hairiness click-clack open gate manual gearbox with a gear knob the size of a planet on top with one basic gear ratio option while an alternative option for a shorter fifth gear ratio was offered But if you go for that you miss out on the 216mph top speed The actual ‘box is asymmetric and mounted on the central tunnel so it’s closer to the steering wheel for better control while manhandling this beast so it’s been stripped out of all essentials unlike most GTRs that were incredibly selfish with one seat the driver’s carbon fibre bucket seat was moved to ensure a better driving position the transmission tunnel had to be made smaller Standard buttons were replaced with racing switches while a fire extinguisher system from Momo was mounted on the right side of the cockpit with the option of turning it on with a button located on the central tunnel We recommend doing that only if a fire is present And the already custom steering wheel of the Diablo GT was replaced with an even lighter and racier Momo setup the side windows were replaced with Plexiglass with couple of inches cut out for ventilation sweaty race car where the air conditioning has been ripped out in favour of speed But just behind the rear view mirror an air intake was mounted Want it? Better get in contact with Formula Automobile in Allerod, Denmark and have quite a few monies ready. They won’t tell us how much they want for it, but we're sure it's a lot. Look out for your regular round-up of news No money from the licence fee was used to create this website The profits we make from it go back to BBC programme-makers to help fund great new BBC programmes BBC is a trademark of the British Broadcasting Corporation The pattern of climate changes at the end of the last glacial period was discovered in south Scandinavia during the last century arctic tundra was replaced by birch woodland and organic sediments were deposited in lakes The Scandinavian ice sheet (SIS) retreated from its maximum extent In a subsequent reversal to cold conditions arctic plants (typified by Dryas octopetala) replaced birch woodland and the SIS re-advanced These climatic events are recognised widely in northwest Europe and beyond but they are particularly well marked in Scandinavia and the British Isles Multi-proxy studies using many independent lines of biological and geological evidence are needed to quantify the complex late-glacial climate changes and their diverse effects on ecosystems The most detailed multi-proxy study is at Kråkenes Following earlier work on cirque glacier development and vegetation history a multi-disciplinary programme involving 24 scientists from 5 countries studied the biological proxies of pollen and oribatid mites and the physical proxies of sediment composition and structure atmospheric CO2 reconstruction from stomatal density of fossil leaves The results are described in over 28 publications combines the high resolution XRF titanium record in the sediments (influenced by erosion in the cirque behind the lake) with previous temperature records from Kråkenes and the neighbouring sea to demonstrate stable cold climate in the early Younger Dryas (YD) After the Vedde Ash layer was deposited at 12120 cal yr BP the climate oscillated between warmer and cold conditions culminating in the major warming at the start of the Holocene These results contributed to understanding the synoptic circulation patterns and processes during the YD over northwest Europe and the force behind the rapid switch (5-10 years) to the interglacial climate of the Holocene Our high-resolution chronology is pivotal at Kråkenes the age of the YD-Holocene boundary was determined to 11,530 ± 50 cal yr BP were precisely dated allowing their use as time markers in other sediment sequences and rates of change in the biota and ecosystems through the Allerød-YD and YD-Holocene boundaries and the succession of ecosystem and biodiversity development in the early Holocene were determined The transformation from tundra to shrub-dominated vegetation within 50 years shows the potential for biota to react to rapid climate warming Jansvatnet in Hammerfest is probably the most northerly terrestrial late-glacial site in the world and is currently under study Vegetation responses (plant macrofossil and pollen analyses) and lake responses (diatoms and chironomids) demonstrate an arctic climate during the Allerød and even colder conditions during the YD Temperatures were inferred from the changing chironomid fauna The length of the ice-free season on the lake was reconstructed from the diatom record the first time this has been achieved during the late-glacial birch trees are at their northern limit here but they were much more abundant in the early Holocene These warmer temperatures decreased to those like today after about 1000 years Tree birch arrived some 1200 years after the start of the Holocene whereas at Kråkenes the lag was about 650 years plant macrofossil and pollen analyses show vegetation responses to the late-glacial climate changes as part of the ongoing ARCTREC (ARCTic RECords of climate) NFR project the Allerød was cold compared to further south Holocene birch woodland was established after about 1000 years Mean July temperatures will be inferred from the chironomid record and by a newly developed method using plant macrofossils Using climatic and vegetational reconstructions from Lusvatnet ARCTREC will attempt to synthesise the complex synoptic climate changes in atmosphere and ocean through the glacial-Holocene transition including the warmest period before 7000 years ago in the north Norwegian area the approach of reconstructing chironomid-inferred temperatures pioneered at Kråkenes has been applied to two late-glacial sites and combined with past glacial activity to reveal a strong oceanic–continental gradient from the Isle of Skye on the west coast to the Cairngorm Mountains in eastern Scotland has a well-studied late-glacial pollen and macrofossil history Several tephra layers have been recognised in the new cores and been precisely radiocarbon dated on associated terrestrial plant remains has been securely dated for the first time and is now a good chronostratigraphic marker particularly for marine late-glacial cores where accurate 14C dating is difficult (2009) Rapid oceanic and atmospheric changes during the Younger Dryas cold period Two terrestrial records of rapid climate change during the glacial-Holocene transition (14,000-9000 calendar years B.P.) from Europe Proceedings National Academy of Sciences USA 97: 1390-1394 (2000) The development of the aquatic ecosystem at Kråkenes Lake during the late glacial and early Holocene - a synthesis (1996) New radiocarbon dates for the Vedde Ash and the Saksunarvatn Ash from western Norway  Lateglacial and early Holocene vegetation and climate gradients in the Nordfjord-Ålesund area (2008) Biological responses to rapid climate change at the Younger Dryas–Holocene transition – succession (1998) A calendar age estimate of the Younger Dryas - Holocene boundary at Kråkenes The Local Europe ABVästmannagatan 43113 25 StockholmSweden Please log in here to leave a comment is one of the results of a 26year long series of innovations which began with the Well Tractor® the conveying device that launched Welltec in place as a top draw subsurface solutions service provider The company’s Development and Engineering (D&E) department is responsible for bringing new ideas to life and transforming innovation into reality It is this ability to think differently and then do differently that forms the foundations on which Welltec is built The company manufactures her products in-house embedding automated processes to proffer completions and interventions solutions The main Manufacturing sites are based in Denmark with Intervention services produced in Allerød a small community just north of Copenhagen Below are pictures from a recent tour to the company’s facilities at Allerød and Esbjerg Click here to cancel reply. Send comment email us at: subscriptions@africaoilgasreport.com Phone: +2348038882629+234-803 652 5979 © 2025 Festac News Press Ltd. Kristan Heneage provides the lowdown on the 20-year-old centre-back currently on loan at Borussia Monchengladbach who has been spoken of as a potential long-term successor to John Terry.. Current club: Borussia Monchengladbach (on loan from Chelsea) (35 apps There’s no denying Chelsea have struggled defensively this season with the strong backline that has so often guided them to Premier League titles absent for most of the campaign With Antonio Conte set to take charge in the summer and John Terry and Branislav Ivanovic now past their best the club may look to usher in a new generation of players ahead of next term and Andreas Christensen is well placed to make the breakthrough Christensen had to wait about 18 months for his professional debut which came in a League Cup tie with Shrewsbury Town in October 2012 Jose Mourinho was impressed with the centre-back’s performance later telling reporters that “the man of the match was Andreas Christensen and again included him in his starting XI against Bradford City in the FA Cup Things didn't go so well for Chelsea on that occasion as the Bantams completed one of the biggest shocks in the competition’s history by winning at Stamford Bridge but Christensen soon got his first taste of Premier League action against Sunderland in May A two-year loan deal to Borussia Monchengladbach then followed last summer and Christensen has started 27 games in the Bundesliga so far.  He’s reserved some of his best displays for the biggest stage of all Christensen shining in Champions League clashes with Juventus and Sevilla Christensen certainly looks to have a future at Chelsea something you might not necessarily have said earlier in the season: the Dane was shaky as Gladbach were thrashed 4-0 by Borussia Dortmund on his debut but he’s since bounced back and was named the club’s player of the month in November and January He’s also reserved some of his best displays for the biggest stage of all, shining in Champions League clashes with Juventus and Sevilla Chelsea aren’t the only ones who have taken note of his performances this term, however: Barcelona and Bayern Munich have been linked with a move this summer but the Blues are reportedly keen to keep the 20-year-old at Stamford Bridge His 87 per cent pass completion rate this term is higher than Borussia Dortmund’s highly-rated ball-playing centre-half Mats Hummels while his ability to hit long balls forward as well as shorter passes across the back makes him a useful asset having conceded just 10 fouls and one yellow card all year while his reading of the game is another attribute that marks him out as an extremely promising young defender – it’s notable that Christensen averages more interceptions per game than Jerome Boateng Christensen demonstrates his composure in possession Gladbach colleague Yann Sommer has also praised his maturity insisting that “he’s young but you can’t see it on the pitch… he looks really experienced.” He’s won just 55% of his aerial duels in the Bundesliga this season – 14% fewer than Boateng and 17% fewer than Hummels I am sure that he will be a top footballer and one of the future men for Chelsea Terry may want to keep playing for as long as possible but his comments on Christensen show how highly he regards the Brondby academy product “I’ve always told [him] that he should chase me and knock me off the team,” he told TV2 Sporten “He should be hungry to take my place I am sure that he will be a top footballer and one of the future men for Chelsea.” Denmark manager Åge Hareide has also heaped praise on the prospect “He reminds me of Franz Beckenbauer,” Hareide said “He still has work to do to reach him – in his playing style – because he’s really relaxed and elegant It almost looks like he could be playing in a suit.” Christensen did not start out in the position he currently plays; in his early days the defender focused more on scoring goals than stopping them The centre-back displayed his predatory instinct against Werder Bremen recently Asked when he had last scored two goals in a game he replied: “It must be… I think it must be even before I went to Chelsea when I was an under-15 or 16 or something like that It hasn’t happened in a long time.” Chelsea reportedly want their man back for the start of Conte’s revolution but Gladbach remain adamant he’s going nowhere “I haven’t talked to Andreas about Chelsea’s next manager or if he would be interested in going back to Chelsea,” his dad has been quoted as saying “Andreas is at Borussia for two years He should just focus on playing football and finishing the season We have an agreement with Borussia to sit down and talk this summer to evaluate the first year We haven’t heard from Chelsea or others told The Set Pieces: “It’s hard to say because if I go back and don’t get the opportunity I’m thinking about doing my two seasons doing as good as I can and then seeing what the future holds a successful career looks to be on the cards for the Dane More features every day on FFT.com • More Chelsea