Land-Sea Linkages in the Arctic Active
The Arctic is undergoing historically unprecedented changes in weather, sea ice, temperature and ecosystems. These changes have led to greater coastal erosion, greater export of freshwater, and changes to marine and terrestrial ecosystems, habitats, and productivity, among other trends. Meanwhile, many believe the Arctic “amplifies” large climate changes during both warm periods and ice ages and Arctic sea-ice cover even affects weather in heavily populated mid-latitude regions. The causes of Arctic amplification are poorly understood. Because instrumental records extend back only a few decades and climate varies on annual, decadal and longer time scales, the causes of ongoing Arctic climate change remain unclear. Thus, there is a growing need to combine instrumental and geologic records to understand how the Arctic Ocean and adjacent land masses have been influenced by a range of natural and anthropogenic factors. We are investigating the history of the Arctic Ocean, adjacent seas and land areas during the last 500,000 years to understand past sea ice history during periods of climate warming and to determine impacts on ecosystems and species.
Our Research: We are investigating the history of the Arctic Ocean and adjacent seas and land areas during the last 500,000 years. During this time, climate varied from ice ages with large ice sheets (glacial periods) to warmer conditions (interglacial periods), with shorter-term fluctuations also occurring. Warm climate intervals such as the early Holocene (~5,000-11,500 years ago), the Last Interglacial Period (~ 125,000-130,000 years ago), and Marine Oxygen Isotope Stage 11 (~400,000 to 450,000 years ago) are of particular interest as they may be comparable to warmer conditions in the future.
Why this Research is Important: Climate and sea ice models did not predict the recent decline in sea ice and do not adequately predict the future of Arctic Ocean sea ice cover. In addition, instrumental records of temperature, precipitation, and sea-ice extent and thickness are available only for approximately the past century and only since 1979 for sea-ice satellite data. This time period is too short to document the causes of observed trends in sea ice and other related Arctic features. Paleoclimate records in Arctic Ocean sediments improve the understanding and modeling of patterns and causes of Arctic climate change. They also shed light on possible future climate change and the impacts of Arctic sea ice on mid-latitude weather. This research informs decision makers on issues related to ecosystems, endangered species, energy policy, national security, and transportation.
Paleoclimate reconstructions from the Arctic already suggest that recent atmospheric warming has reversed the regional climatic trends of the last few millennia. During recent decades, Arctic temperatures have increased while annual and seasonal Arctic Ocean sea ice cover has decreased. This has led to greater coastal erosion, greater export of freshwater, and changes in marine ecosystems, habitats, and productivity among other trends. Of particular concern is the decrease in Arctic sea ice extent and thickness since 1979, especially during summer months, which has outpaced the rates predicted by climate models. Because instrumental records extend back only a few decades and large interannual and decadal variability exists, the causes of ongoing Arctic climate change remain unclear. In addition, atmospheric carbon dioxide concentrations are approaching levels not seen in 3 million years. Thus, there is a growing need to understand how the Arctic Ocean responds to climate change caused by both natural and anthropogenic factors.
Objective(s): Major goals are to understand past Arctic sea ice history during past periods of climate warming and to determine impacts on ecosystems and species.
Methods: USGS researchers, collaborating with scientists in the United States, Sweden, Germany and elsewhere, are collecting evidence from sediment cores in the Arctic Ocean and adjacent seas and land masses. The cores are used to determine how Arctic systems were affected by changing climate in the past and to help predict future changes. Scientists use different proxy methods to reconstruct past patterns in Arctic sea ice, ocean temperature, and bottom and surface ocean circulation. Reconstruction of sea ice history over the last 500,000 years uses evidence from sediment cores and surface sediment samples. The samples are collected from Arctic continental shelves, abyssal plains, the Yermak Plateau, the Morris Jesup Rise, and the Alpha, Lomonosov, and Mendeleev Ridges (see map). Benthic organisms (which live on the ocean floor) are influenced by bottom water temperatures and patterns of ocean circulation. In addition to controlling which species are present, water temperatures also affect the chemistry of their shells. To reconstruct patterns of past water temperature and circulation, analyses of the ratio of Mg/Ca in ostracode shells are combined with analyses of species composition. Records of ocean and land temperature during the last 12,000 years (Holocene) are being studied in Alaska and the Beaufort-Chukchi Sea region and compared to recent ocean warming in that region. The focus is currently on sites in the Northwind Ridge and Chukchi Sea region north of Alaska to improve understanding of Arctic Ocean temperature and circulation during past warm intervals.
Below are publications associated with this project.
Constraints on Lake Agassiz discharge through the late-glacial Champlain Sea (St. Lawrence Lowlands, Canada) using salinity proxies and an estuarine circulation model
Western Arctic Ocean temperature variability during the last 8000 years
Quaternary Sea-ice history in the Arctic Ocean based on a new Ostracode sea-ice proxy
Modern climate challenges and the geological record
Morphological variability of the planktonic foraminifer Neogloboquadrina pachyderma from ACEX cores: Implications for late pleistocene circulation in the Arctic Ocean
Quaternary paleoceanography of the central Arctic based on Integrated Ocean Drilling Program Arctic Coring Expedition 302 foraminiferal assemblages
Constraints on the Pleistocene chronology of sediments from the Lomonosov Ridge
Rapid sea level rise and ice sheet response to 8,200-year climate event
The Cenozoic palaeoenvironment of the Arctic Ocean
Episodic fresh surface waters in the Eocene Arctic Ocean
Reconstructing late Quaternary deep-water masses in the eastern Arctic Ocean using benthonic Ostracoda
North Atlantic deepwater temperature change during late pliocene and late quaternary climatic cycles
Below are news stories associated with this project.
- Overview
The Arctic is undergoing historically unprecedented changes in weather, sea ice, temperature and ecosystems. These changes have led to greater coastal erosion, greater export of freshwater, and changes to marine and terrestrial ecosystems, habitats, and productivity, among other trends. Meanwhile, many believe the Arctic “amplifies” large climate changes during both warm periods and ice ages and Arctic sea-ice cover even affects weather in heavily populated mid-latitude regions. The causes of Arctic amplification are poorly understood. Because instrumental records extend back only a few decades and climate varies on annual, decadal and longer time scales, the causes of ongoing Arctic climate change remain unclear. Thus, there is a growing need to combine instrumental and geologic records to understand how the Arctic Ocean and adjacent land masses have been influenced by a range of natural and anthropogenic factors. We are investigating the history of the Arctic Ocean, adjacent seas and land areas during the last 500,000 years to understand past sea ice history during periods of climate warming and to determine impacts on ecosystems and species.
Our Research: We are investigating the history of the Arctic Ocean and adjacent seas and land areas during the last 500,000 years. During this time, climate varied from ice ages with large ice sheets (glacial periods) to warmer conditions (interglacial periods), with shorter-term fluctuations also occurring. Warm climate intervals such as the early Holocene (~5,000-11,500 years ago), the Last Interglacial Period (~ 125,000-130,000 years ago), and Marine Oxygen Isotope Stage 11 (~400,000 to 450,000 years ago) are of particular interest as they may be comparable to warmer conditions in the future.
Why this Research is Important: Climate and sea ice models did not predict the recent decline in sea ice and do not adequately predict the future of Arctic Ocean sea ice cover. In addition, instrumental records of temperature, precipitation, and sea-ice extent and thickness are available only for approximately the past century and only since 1979 for sea-ice satellite data. This time period is too short to document the causes of observed trends in sea ice and other related Arctic features. Paleoclimate records in Arctic Ocean sediments improve the understanding and modeling of patterns and causes of Arctic climate change. They also shed light on possible future climate change and the impacts of Arctic sea ice on mid-latitude weather. This research informs decision makers on issues related to ecosystems, endangered species, energy policy, national security, and transportation.
Paleoclimate reconstructions from the Arctic already suggest that recent atmospheric warming has reversed the regional climatic trends of the last few millennia. During recent decades, Arctic temperatures have increased while annual and seasonal Arctic Ocean sea ice cover has decreased. This has led to greater coastal erosion, greater export of freshwater, and changes in marine ecosystems, habitats, and productivity among other trends. Of particular concern is the decrease in Arctic sea ice extent and thickness since 1979, especially during summer months, which has outpaced the rates predicted by climate models. Because instrumental records extend back only a few decades and large interannual and decadal variability exists, the causes of ongoing Arctic climate change remain unclear. In addition, atmospheric carbon dioxide concentrations are approaching levels not seen in 3 million years. Thus, there is a growing need to understand how the Arctic Ocean responds to climate change caused by both natural and anthropogenic factors.
Objective(s): Major goals are to understand past Arctic sea ice history during past periods of climate warming and to determine impacts on ecosystems and species.
Methods: USGS researchers, collaborating with scientists in the United States, Sweden, Germany and elsewhere, are collecting evidence from sediment cores in the Arctic Ocean and adjacent seas and land masses. The cores are used to determine how Arctic systems were affected by changing climate in the past and to help predict future changes. Scientists use different proxy methods to reconstruct past patterns in Arctic sea ice, ocean temperature, and bottom and surface ocean circulation. Reconstruction of sea ice history over the last 500,000 years uses evidence from sediment cores and surface sediment samples. The samples are collected from Arctic continental shelves, abyssal plains, the Yermak Plateau, the Morris Jesup Rise, and the Alpha, Lomonosov, and Mendeleev Ridges (see map). Benthic organisms (which live on the ocean floor) are influenced by bottom water temperatures and patterns of ocean circulation. In addition to controlling which species are present, water temperatures also affect the chemistry of their shells. To reconstruct patterns of past water temperature and circulation, analyses of the ratio of Mg/Ca in ostracode shells are combined with analyses of species composition. Records of ocean and land temperature during the last 12,000 years (Holocene) are being studied in Alaska and the Beaufort-Chukchi Sea region and compared to recent ocean warming in that region. The focus is currently on sites in the Northwind Ridge and Chukchi Sea region north of Alaska to improve understanding of Arctic Ocean temperature and circulation during past warm intervals.
- Publications
Below are publications associated with this project.
Filter Total Items: 37Constraints on Lake Agassiz discharge through the late-glacial Champlain Sea (St. Lawrence Lowlands, Canada) using salinity proxies and an estuarine circulation model
During the last deglaciation, abrupt freshwater discharge events from proglacial lakes in North America, such as glacial Lake Agassiz, are believed to have drained into the North Atlantic Ocean, causing large shifts in climate by weakening the formation of North Atlantic Deep Water and decreasing ocean heat transport to high northern latitudes. These discharges were caused by changes in lake drainAuthorsBrian Katz, R.G. Najjar, T. Cronin, J. Rayburn, M. E. MannWestern Arctic Ocean temperature variability during the last 8000 years
We reconstructed subsurface (∼200–400 m) ocean temperature and sea-ice cover in the Canada Basin, western Arctic Ocean from foraminiferal δ18O, ostracode Mg/Ca ratios, and dinocyst assemblages from two sediment core records covering the last 8000 years. Results show mean temperature varied from −1 to 0.5°C and −0.5 to 1.5°C at 203 and 369 m water depths, respectively. Centennial-scale warm periodsAuthorsJesse R. Farmer, Thomas M. Cronin, Anne De Vernal, Gary S. Dwyer, Loyd D. Keigwin, Robert C. ThunellQuaternary Sea-ice history in the Arctic Ocean based on a new Ostracode sea-ice proxy
Paleo-sea-ice history in the Arctic Ocean was reconstructed using the sea-ice dwelling ostracode Acetabulastoma arcticum from late Quaternary sediments from the Mendeleyev, Lomonosov, and Gakkel Ridges, the Morris Jesup Rise and the Yermak Plateau. Results suggest intermittently high levels of perennial sea ice in the central Arctic Ocean during Marine Isotope Stage (MIS) 3 (25-45 ka), minimal seaAuthorsT. M. Cronin, L. Gemery, W.M. Briggs, M. Jakobsson, L. Polyak, E. M. BrouwersModern climate challenges and the geological record
Today's changing climate poses challenges about the influence of human activity, such as greenhouse gas emissions and land use changes, the natural variability of Earth's climate, and complex feedback processes. Ice core and instrumental records show that over the last century, atmospheric carbon dioxide (CO2) concentrations have risen to 390 parts per million volume (ppmv), about 40% above pre-InAuthorsThomas M. CroninMorphological variability of the planktonic foraminifer Neogloboquadrina pachyderma from ACEX cores: Implications for late pleistocene circulation in the Arctic Ocean
Planktonic foraminifera populations were studied throughout the top 25 meters of the IODP ACEX 302 Hole 4C from the central Arctic Ocean at a resolution varying from 5cm (at the top of the record) to 10cm. Planktonic foraminifera occur in high absolute abundances only in the uppermost fifty centimetres and are dominated by the taxa Neogloboquadrina pachyderma. Except for a few intermittent layersAuthorsF. Eynaud, T. M. Cronin, S.A. Smith, S. Zaragosi, J. Mavel, Y. Mary, V. Mas, C. PujolQuaternary paleoceanography of the central Arctic based on Integrated Ocean Drilling Program Arctic Coring Expedition 302 foraminiferal assemblages
The Integrated Ocean Drilling Program (IODP) Arctic Coring Expedition (ACEX) Hole 4C from the Lomonosov Ridge in the central Arctic Ocean recovered a continuous 18 in record of Quaternary foraminifera yielding evidence for seasonally ice-free interglacials during the Matuyama, progressive development of large glacials during the mid-Pleistocene transition (MPT) ???1.2-0.9 Ma, and the onset of highAuthorsT. M. Cronin, S.A. Smith, F. Eynaud, M. O'Regan, J. KingConstraints on the Pleistocene chronology of sediments from the Lomonosov Ridge
Despite its importance in the global climate system, age-calibrated marine geologic records reflecting the evolultion of glacial cycles through the Pleistocene are largely absent from the central Arctic Ocean. This is especially true for sediments older than 200 ka. Three sites cored during the Integrated Ocean Drilling Program's Expedition 302, the Arctic Coring Expedition (ACEX), provide a 27 mAuthorsM. O'Regan, J. King, J. Backman, M. Jakobsson, H. Palike, K. Moran, C. Heil, T. Sakamoto, T. M. Cronin, R.W. JordanRapid sea level rise and ice sheet response to 8,200-year climate event
The largest abrupt climatic reversal of the Holocene interglacial, the cooling event 8.6–8.2 thousand years ago (ka), was probably caused by catastrophic release of glacial Lake Agassiz-Ojibway, which slowed Atlantic meridional overturning circulation (AMOC) and cooled global climate. Geophysical surveys and sediment cores from Chesapeake Bay reveal the pattern of sea level rise during this event.AuthorsT. M. Cronin, P.R. Vogt, D. A. Willard, R. Thunell, J. Halka, M. Berke, J. PohlmanThe Cenozoic palaeoenvironment of the Arctic Ocean
The history of the Arctic Ocean during the Cenozoic era (0–65 million years ago) is largely unknown from direct evidence. Here we present a Cenozoic palaeoceanographic record constructed from >400 m of sediment core from a recent drilling expedition to the Lomonosov ridge in the Arctic Ocean. Our record shows a palaeoenvironmental transition from a warm ‘greenhouse’ world, during the late PalaeoceAuthorsK. Moran, J. Backman, H. Brinkhuis, S.C. Clemens, Thomas M. Cronin, G.R. Dickens, F. Eynaud, J. Gattacceca, M. Jakobsson, R.W. Jordan, M. Kaminski, J. King, N. Koc, A. Krylov, N. Martinez, J. Matthiessen, D. McInroy, T.C. Moore, J. Onodera, M. O'Regan, H. Palike, B. Rea, D. Rio, T. Sakamoto, D. C. Smith, R. Stein, John K. St, I. Suto, N. Suzuki, K. Takahashi, M. E. Watanabe, M. Yamamoto, J. Farrell, M. Frank, P. Kubik, W. Jokat, Y. KristoffersenEpisodic fresh surface waters in the Eocene Arctic Ocean
It has been suggested, on the basis of modern hydrology and fully coupled palaeoclimate simulations, that the warm greenhouse conditions that characterized the early Palaeogene period (55-45 Myr ago) probably induced an intensified hydrological cycle with precipitation exceeding evaporation at high latitudes. Little field evidence, however, has been available to constrain oceanic conditions in theAuthorsH. Brinkhuis, S. Schouten, M.E. Collinson, A. Sluijs, J.S.S. Damste, G.R. Dickens, M. Huber, T. M. Cronin, J. Onodera, K. Takahashi, J.P. Bujak, R. Stein, J. Van Der Burgh, J.S. Eldrett, I.C. Harding, A.F. Lotter, F. Sangiorgi, H.V.K.V. Cittert, J. W. De Leeuw, J. Matthiessen, J. Backman, K. MoranReconstructing late Quaternary deep-water masses in the eastern Arctic Ocean using benthonic Ostracoda
The distribution of Ostracoda in three long cores from the deep eastern Arctic Ocean was studied to determine the palaeoceanographical history of the Eurasian Basin during the late Quaternary. The samples for this study were obtained from the Lomonosov Ridge, Morris Jesup Rise and Yermak Plateau during the Arctic 91 expedition. Ostracoda previously studied in coretops at the same sites as the presAuthorsR. Ll Jones, R.C. Whatley, T. M. Cronin, H.J. DowsettNorth Atlantic deepwater temperature change during late pliocene and late quaternary climatic cycles
Variations in the ratio of magnesium to calcium (Mg/Ca) in fossil ostracodes from Deep Sea Drilling Project Site 607 in the deep North Atlantic show that the change in bottom water temperature during late Pliocene 41,000-year obliquity cycles averaged 1.5°C between 3.2 and 2.8 million years ago (Ma) and increased to 2.3°C between 2.8 and 2.3 Ma, coincidentally with the intensification of NorthernAuthorsGary S. Dwyer, T. M. Cronin, P.A. Baker, M.E. Raymo, Jeffrey S. Buzas, T. Correge - News
Below are news stories associated with this project.