Sediments of Lake Baikal reach thicknesses in excess of 7 kilometers (4 miles), and the rift floor is perhaps 8 to 9 kilometers (more than 5 miles) deep, making it one of the deepest active rifts on Earth. The shallowest sediments may contain the only known freshwater occurrence of natural gas hydrates. Maps of complex fault patterns and changing depositional environments provide the first opportunities to describe the development of the lake and to help explain its unique flora and fauna.
Unique characteristics of the Lake Baikal environment combine to produce an especially promising site for studies of climate history.
Baikal is the largest freshwater lake on Earth containing 23,000 cubic kilometers of water, or roughly 20 percent of the world's total surface fresh water. It contains as much fresh water as the Great Lakes of North America combined. At over 1,600 meters (5250 feet), it is the deepest lake in the world, and at perhaps more than 25 million years old, the oldest as well. The water of Lake Baikal is so fresh that calcium carbonate does not survive in the fossil record. Despite the lake's great depth, its water is well-oxygenated throughout creating unique biological habitats.
The high latitude of Lake Baikal makes it particularly sensitive to climatic variations.
Climate variations, including those resulting from atmospheric accumulation of carbon dioxide, are more pronounced at higher latitudes. Although the lake contains a record of glaciation of surrounding mountains in its sediments, it is unique among large, high-latitude lakes in that its sediments have not been scoured by overriding continental ice sheets.
United States and Russian studies of sediment cores taken from Lake Baikal provide a detailed record of climatic variation over the past 250,000 years.
Much attention is focused on numerical models of climate change but there have been few means for reliably testing or modifying boundary conditions of general circulation models. Studies of sedimentary environments in Lake Baikal provide important opportunities to establish ground truth for general circulation models. Very little data exist for long-term climate change from continental interiors; most of the data record derives from the marine or maritime environments. Finally, studies of past environments contribute to understanding the extent to which human activity affects natural conditions in the lake.
