The sedimentary record of Lake El'gygytgyn, an impact crater in northeastern Siberia, has become a focus for paleoclimatic research and is now considered a high-priority, world-class target for drilling by the International Continental Drilling Program (ICDP). Sediment cores retrieved from the deepest part of the lake (170 m) in 1998 and 2003 revealed a basal age of ~ 250 and nearly 300 ka, and reproducibly demonstrated the sensitivity of the lake to climatic change across NE Asia at millennial timescales. These cores are the oldest terrestrial Arctic cores yet retrieved. This grant will support acquiring deeper cores in spring 2008 through to bedrock. The cores could potentially yield a record of Arctic climate dating back to over 3 My ago. Seismic measurements show 400 m of sediments overlying the impact breccias. This grant is the U.S. contribution to a multi-national effort to retrieve the cores and carry out subsequent scientific research, joining contributions from the ICDP, the Canadian, German and Russian governments. Intellectual merit: The goal is to collect and interpret the longest time-continuous record of climate change in the terrestrial Arctic and compare this record with those from lower latitude marine and terrestrial sites to better understand hemispheric and global climate change. Coring objectives include 2 replicate overlapping cores at 2 sites near the deepest part of the lake. One additional land-based core on lake sediments now overlain by frozen alluvial sediments will allow a better understanding of sediment supply to the lake. These cores will provide a unique Arctic record capturing the mechanisms and dynamics of glacial/interglacial and millennial-scale change for comparison with other long records from the oceans. This will allow scientists to evaluate and model systemic teleconnections and leads/lags relative to insolation forcing during periods of both 41 ka and 100 ka cycling. This record will provide insight as to whether rapid change events identified during the last glacial cycle are typical of earlier glacial periods. This core will allow us to address questions concerning the evolution and mode of Arctic climate change via the transition from the warm middle Pliocene to the onset of the first major Northern Hemisphere glaciation. The cores will provide a record of the regional sensitivity of the N E Asian Arctic to millennial-scale abrupt change and interglacial warmth detected in the timeframe of the EPICA ice cores, long Asian loess and lake records, and marine records. Broader impacts: This work will help us understand the background of natural variations in Arctic climate so that modern changes can be understood within that context. As this work will occur during the International Polar Year (IPY), the retrieval of a unique Arctic core will be especially timely. International sharing of research builds trust and mutual respect between our nations and individuals, but also between political bodies and institutions in Moscow and the more remote regions of Russia. This proposal will support graduate and undergraduates at 4 U.S. institutions. A large portion of the outreach efforts will be internet-based, incorporating the latest interactive 3D GIS and terrain visualization technology, video, and real-time interactions with educators in the field, all tying this project into the IPY.
El’gygytgyn Crater, located 100 km north of the Arctic Circle, NE Russia, was produced by a meteorite impact 3.6 million years ago during a geologic interval called the Pliocene (~5.3 to 2.5 million years ago). At this time, climate conditions on Earth were warm even in the high latitudes. The impact formed a crater ~18 km across that filled with water establishing the earliest Lake El’gygytgyn on the continental divide between the Arctic Ocean and the Bering Sea (Fig 1). Today the pristine, low nutrient lake measures ~12 km in diameter and 170 m deep. It is the largest, oldest deep lake in the entire Arctic. Our studies at "Lake E" were motivated by the need to understand the role of the Earth’s high latitude regions in global climate change. Today, the tropics act as the "heat engine" of the planet receiving solar energy that drives atmospheric convection. The heat from both the tropical atmosphere and oceans is transported toward the polar regions – in this process, heat is lost providing balance in the Earth system. The causes and responses to climate change on Earth are complex – a change to any individual component of the climate system (for example, a change in temperature to the oceans or the land) may impact the entire global climate system, though interactions between different processes in the climate system or "feedbacks". Currently, a dramatic increase in greenhouse gases (for example, carbon dioxide and methane) in Earth’s atmosphere, driven by human activities, is warming the planet rapidly providing the impetus for the science community to learn more concerning the complexities of the Earth system at regional and global scales. By understanding what natural processes and feedbacks in the Earth system drove changes in climate in the past, scientists can provide society and governments with better predictions, with lower uncertainities, about the rates and magnitude of changes we will see in the coming decades and centuries. Climate change impacts every dimension of society from food supplies, water, natural resources, to natural disasters including flood and drought. In early 2009 we recovered a 3.6 million year-long sediment record from Lake E, one of the most remote regions of Russian Beringia (Fig 2 and Fig. 3). Sediment (mud) washed into the lake accumulates over time and contains geochemical/biological indicators of climate and environmental conditions at the time it was deposited – for example, pollen from plants tells us what types of vegetation once surrounded the lake. Examining chemical, geological, biological indicators, we reconstructed a number of past environmental parameters including temperature and precipitation, almost like having a weather station on site back in time. This work informs us of the sensitivity of the Arctic to climate change and provides a means of testing climate models in their ability to properly characterize polar amplification – the fact that the polar regions warm more and at a faster rate than the rest of the world. For all partners involved, the successful operations were a major milestone for the International Polar Year 2007-2009 (Fig 5). Our work provides the longest time-continuous Arctic paleoclimate record of alternating glacial-interglacial change. The warmest, wettest time interval occurred from ~3.58-3.34 million years ago and was dominated by exceptional tree pollen implying July temperatures nearly 7-8o C warmer than today with nearly ~3 times the annual precipitation. In fact the modern analog reconstructions for pollen spectra at Lake El’gygytgyn from 3.02 to 3.26 million years ago are notably warmer than the mean of 11 ensemble runs for the Pliocene Model Intercomparison Project conducted by modeling scientists. Atmospheric carbon dioxide (CO2) levels are estimated to have been 360 to 400 ppm (like what humans have done to Earth over the last 100 years) implying exceptionally high climate sensitivity and polar amplification. Extreme warmth in the middle Pliocene Arctic from 3.6-3.4 millions years ago and 3.2 to 3.0 millions years ago occurs at the same time the Antarctic Drilling Program results suggest the West Antarctic Ice Sheet was did not exist. The Pliocene-Pleistocene (ice age) climate evolution of the Arctic must have modulated the glacial history of Greenland and we have tested this with computer modeling experiments. A variety of proxies show pronounced glacial episodes started ~2.6 million years ago, but the full range of typical glacial/interglacial change wasn’t established until ~1.8 millions years ago. Numerous "superinterglacials" occur during the ice age record, with maximum summer temperatures and annual precipitation especially 320,000 years, 410,000 years and 1.1 million years ago. The unprecedented geology from Lake E, especially the history of past interglacials, provides a fresh means of testing the magnitude of polar amplification over time, and sensitivity of the Greenland and West Antarctic Ice Sheets to respond dramatically to small changes in the Earth system. It provides a new challenge to understanding global processes.
