This project investigates paleoceanographic and climatic history of the Arctic Ocean and adjacent seas during the last 500,000 years when large glacial to interglacial and millennial climate fluctuations occurred. Warm climatic intervals such as the early Holocene (~5,000-11,500 years ago), the Last Interglacial Period (the Eemian Interglacial, ~ 125,000-130,000 years ago), and Marine Oxygen Isotope Stage 11 (~400,000 to 450,000 years ago) are of particular interest due to concern about future climatic warming. This project uses various proxy methods that address the history of Arctic sea ice, bottom and surface ocean circulation, and ocean temperature variability. Sea ice history over the last 500,000 years has been studied using sediment cores and surface sediment samples from Arctic continental shelves, abyssal plains, the Lomonosov, Mendeleev, and Gakkel Ridges, the Yermak Plateau, and Morris Jesup Rise (see map). Arctic bottom water temperatures and ocean circulation were also reconstructed using ostracode Mg/Ca ratios and faunal analyses. Holocene ocean temperatures were studied in the Beaufort-Chukchi Sea region off northern Alaska and compared to recent ocean warming in that region. Current focus is on Arctic Ocean climate during past warm interglacial periods in the Northwind Ridge and Chukchi Sea region north of Alaska.
Why is this research important?
Paleoclimate reconstructions from the Arctic suggest that recent atmospheric warming has reversed 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, leading to greater coastal erosion, changes in marine ecosystems, habitats, and productivity, and greater export of freshwater, 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 due to large interannual and decadal variability, 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. Paleoclimate records preserved in Arctic Ocean sediments improve understanding of patterns and causes of Arctic climate change, shed light on possible future climate change, and help decision makers on issues related to ecosystems, endangered species, energy policy, and transportation.