Lake Baikal is the world's most voluminous lake—holding about 20 percent of Earth's liquid freshwater—and a treasure trove of biodiversity and unique species. However, the lake is in one of the world's most rapidly warming regions. The lake's temperature has risen dramatically since the 1940s,threatening its fish and other aquatic creatures. 1

Key Facts Lake Baikal is home to more species than any other lake in the world, a large proportion of which are found nowhere else on Earth.2 Rapidly rising lake temperatures and ecosystem changes since the 1940s—both linked to global climate change—could fundamentally change the lake.6,7 Since 1946, the surface waters of Lake Baikal have warmed by 2.1° F (1.2° C). 7 The annual ice–free season has lengthened, and the thickness of the ice has decreased by an average of 30 inches (12 centimeters) in the same time period. 8

The annual ice–free season has lengthened, and the thickness of the ice has decreased by an average of 30 inches (12 centimeters) in the same time period. Rising lake temperatures since 1979 are linked to a 300 percent increase in blooms of algae, which form the base of the lake's food chain. 7

Given a mid–level scenario for future heat–trapping emissions, the region around Lake Baikal is projected to warm by 7.2° to 9° F (4° to 5° C) by the end of the century.14,15 Such dramatic temperature rises are likely to shrink ice cover further and disrupt the lake's amazing ecosystems. Details Lake Baikal is the world's deepest, oldest,and most voluminous lake—equal in volume to the North American Great Lakes combined.2 These qualities have given rise to a phenomenal ecosystem that hosts more species than any other lake in the world. Of its 2,500 animal species, half are unique to the lake.3 One–third of the lake's plant species are also found nowhere else on Earth.4 Most notably, the lake is home to the Baikal seal, the only seal in the world that lives exclusively in freshwater.5 Lake Baikal has undergone dramatic warming and ecosystem changes that could disrupt its biological systems.2,6,7 Since 1892, winter temperatures in the region around Lake Baikal have warmed by 0.5° F (0.3° C) per decade, making this one of the most rapidly warming regions in the world.6 The surface waters of Lake Baikal have also warmed by 2.1° F (1.2° C) since 1946.7 The ice–free season has lengthened by nearly three weeks since 1869, and ice thickness has decreased by an average of 30 inches (12 centimeters) since 1949.8 Both water temperature and ice conditions help determine the types of microscopic plants and animals—known as phytoplankton and zooplankton—that compose the base of Lake Baikal's food chain.9 The lake's phytoplankton include species of plants known as diatoms that are both unusually large and unique to the lake.9 These diatoms have a burst of abundance in the spring when the lake is still covered by clear ice with almost no snow cover.2 The growth and survival of the diatoms depend on clear ice, which allows more light to penetrate than snow-covered ice.10 Because the diatoms are larger than other types of phytoplankton in the lake, they are an energy–rich food source for animals higher up the food chain, such as zooplankton and fish.2 During the summer—after the spring diatom bloom and when the lake is ice–free—smaller, less-energy-rich phytoplankton increase in abundance, and water conditions become less favorable for diatom production.2 Using the amount of chlorophyll in the lake as a measure, scientists have found a 300 percent increase in the summertime abundance of phytoplankton since 1979.7 They have also found a 335 percent rise in a type of zooplankton that feeds on the phytoplankton and thrives in warm waters since 1946.7 Meanwhile other types of zooplankton have declined in abundance.7 These changes have been linked to the recent increases in water temperature and decreases in the amount of ice, and indicate that food-web dynamics in the lake are changing.7 The recent warming of Lake Baikal, and the resulting shortening of the ice season, mean that conditions are more favorable for the smaller, less–energy–rich phytoplankton, and less favorable for the more nutritious diatoms.2,9 The decline of energy-rich food sources means that animals higher up on the food chain cannot feed as efficiently.2 Changes in the phytoplankton community can therefore propagate up the food chain to the lake's fish and mammals.2 The Baikal seal, the lake's top predator, and commercially important omul fish are both linked to the lake's microscopic diatoms through the food chain. Changes in the abundance of the diatoms could have adverse effects on these important species. Part of a Larger Pattern Because lakes integrate changes in their catchment regions and respond quickly to environmental shifts, they are often seen as sentinels of climate change.11 While the mechanisms linking changes in climate to changes in lake ecosystems vary from lake to lake—depending on factors such as location, biology, and geography—clear signals of climate change are emerging from lakes throughout the world.11 In the English Lake District, for example, warming temperatures mean that less mixing is occurring between warm surface waters and cooler deep waters, limiting the amount of oxygen available for animals living in the deeper waters of the region's lakes.12 Similar mechanisms are at work at Africa's Lake Tanganyika, where biological productivity at the base of the food chain has declined by 20 percent since the 1950s because of rising water temperatures.13 What the Future Holds Because heat–trapping emissions are rising as we continue to burn coal, oil, gas, and trees, temperatures in the Siberian region are projected to increase significantly in the future.14 Given a mid–level scenario for future global warming emissions,15 climate models project that this region will warm by 7.2° to 9° F (4° to 5° C) by the end of the century.14 As the climate warms, ice cover will likely continue to shrink, with implications for creatures great and small that call Lake Baikal home.6,9,16 In 1996, UNESCO (the United Nations Educational, Scientific and Cultural Organization) designated Lake Baikal as a World Heritage Site because of its outstanding ecosystem. Along with swift action to reduce our heat–trapping emissions, international efforts to preserve the lake and reduce the industrial legacy of pollution in its surroundings could minimize harmful changes to the lake's unique ecosystems. Credits Endnotes Photograph used with permission of BaikalNature LLC . Online at http://www.flickr.com/photos/baikalnature/4878882526/. Accessed January 8, 2013. ↑ Moore, M.V., S.E. Hampton, L.R. Izmest'eva, E.A. Silow, E.V. Peshkova, and B.K. Pavlov. 2009. Climate change and the world's “Sacred Sea”—Lake Baikal, Siberia. BioScience 59(5):405–417. ↑ Timoshkin, O.A. 1995. Biodiversity of Lake Baikal: Review of current state of knowledge and perspectives of studies. In: Guide and key to pelagic animals of Lake Baikal with ecological notes, O.A. Timoshkin, ed. Nauka (in Russian). Cited in Moore et al. 2009 (see endnote 1).Accessed May 14, 2010. ↑ Bodarenko, N.A., A. Tuji, and M. Nakanishi. 2006. A comparison of phytoplankton communities between the ancient Lakes Biwa and Baikal. Hydrobiolgia 568(suppl. 1):25–29. ↑ Seal Conservation Society. 2010. Baikal seal. Online at http://www.pinnipeds.org/seal-information/species-information-pages/the-phocid-seals/baikal-seal. Accessed September 10, 2011. ↑ Todd, M.C., and A.W. Mackay. 2003. Large-scale climatic controls on Lake Baikal ice cover. Journal of Climate 16:3186–3199. ↑ Hampton, S.E., L.R. Izmest'eva, M.V. Moore, S.L. Katz, B. Dennis, and E.A. Silow. 2008. Sixty years of environmental change in the world's largest freshwater lake–Lake Baikal, Siberia. Global Change Biology 14:1–12. ↑ Shimaraev, M.N., L.N. Kuimova, V.N. Sinyukovich, and V.V. Tsekhanovskii. 2002. Manifestation of global climatic changes in Lake Baikal during the 20th century. Doklady Earth Sciences 383A:288–291. Cited in Hampton et al. 2008 (see endnote 7). ↑ Mackay, A.W., D.B. Ryves, D.W. Morley, D.H. Jewson, and P. Rioual. 2006. Assessing the vulnerability of endemic diatom species in Lake Baikal to predicted future climate change: a multivariate approach. Global Change Biology 12:2297–2315. ↑ Granin, N.G., D.H. Jewson, R.Y. Gnatovsky, L.A. Levin, A.A. Zhdanov, L.A. Gorbunova, V.V. Tsekhanovsky, L.M. Doroschenko, and N.Y. Mogilev. 2000. Turbulent mixing under ice and the growth of diatoms in Lake Bikal. Verhand–lungen Internationale Vereinigung für theroetische und angewandte Limnologie 27:2812–2814. Cited in Moore et al. 2009 (see endnote 1). ↑ Adrian, R., C.M. O'Reilly, H. Zagarese, S.B. Baines, D.O. Hessen, W. Keller, D.M. Livingstone, R. Sommaruga, D. Straile, E. Van Donk, G.A. Weyhenmeyer, and M. Winder. 2009. Lakes as sentinels of climate change. Limnology and Oceanography 54(6):2283–2297. ↑ Foley, B., I.D. Jones, S.C. Maberly, and B. Rippey. 2011. Long–term changes in oxygen depletion in a small temperate lake: effects of climate change and eutrophication. Freshwater Biology doi:10.1111/j.1365-2427.2011.02662.x ↑ O'Reilly, C.M., S.R. Alin, P.–D. Pilsnier, A.S. Cohen, and B.A. McKee. 2003. Climate change decreases aquatic ecosystem productivity of Lake Tanganyika, Africa. Nature 424:766–768. ↑ Christensen, J.H., B. Hewitson, A. Busuioc, A. Chen, X. Gao, I. Held, R. Jones, R.K. Kolli, W.–T. Kwon, R. Laprise, V. Magaña Rueda, L. Mearns, C.G. Menéndez, J. Räisänen, A. Rinke, A. Sarr and P. Whetton. 2007. Regional climate projections. In: Climate change 2007: The physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. S. Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor, and H.L. Miller, eds. Cambridge, UK, and New York, NY: Cambridge University Press. ↑ The scenario referred to here is the middle-emissions pathway known as A1B from the Intergovernmental Panel on Climate Change. ↑ Kouraev, A.V., S.V. Semovski, M.N. Shimaraev, N.M. Mognard, B. Legrésy, and F. Rémy. 2007. The ice regime of Lake Baikal from historical and satellite data: Relationship to air temperature, dynamical, and other factors. Limnology and Oceanography 52(3):1268–1286. ↑