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World’s largest lake ecosys­tem influ­enced by dis­tant cli­mate variability

pub­lished 24 July 2011 | mod­i­fied 20 Feb­ru­ary 2011

Siberia’s Lake Baikal, the world’s old­est, deep­est, and largest fresh­wa­ter lake, has pro­vided sci­en­tists with insight into the ways that cli­mate change affects water tem­per­a­ture, which in turn affects life in the lake. Lake Baikal is not only the world’s largest and most bio­log­i­cally diverse lake, but it has excep­tion­ally strong sea­sonal struc­ture in ecosys­tem dynam­ics that may be dra­mat­i­cally affected by fluc­tu­a­tions in sea­sonal timing.

An extra­or­di­nary, as well as asthon­ish­ing, lon­gi­tu­di­nal study of the lake’s tem­per­a­ture changes pro­vided the research team led by Steve Katz the nec­es­sary data for their work. So, thanks to the ded­i­ca­tion of three gen­er­a­tions of a fam­ily of Russ­ian sci­en­tists, remark­able data on cli­mate and lake tem­per­a­ture were avail­able. This 58-​year record of water tem­per­a­ture from Lake Baikal was exam­ined to deter­mine how sea­son­al­ity in the lake has fluc­tu­ated over the past half cen­tury and to infer under­ly­ing mechanisms.

The research team dis­cov­ered many cli­mate vari­abil­ity sig­nals in the data. For exam­ple, changes in Lake Baikal water tem­per­a­ture cor­re­late with monthly vari­abil­ity in El Niño indices, reflect­ing sea sur­face tem­per­a­tures over the Pacific Ocean tens of thou­sands of kilo­me­ters away. At the same time, Lake Baikal’s tem­per­a­tures are influ­enced by strong inter­ac­tions with Pacific Ocean pres­sure fields described by the Pacific Decadal Oscil­la­tion. The researchers found that sea­son­al­ity of Lake Baikal’s sur­face water tem­per­a­tures relate to the fluc­tu­at­ing inten­sity and path of the jet stream on mul­ti­ple time scales. Although the lake has warmed over the past cen­tury, the chang­ing of sea­sons was not found to trend in a sin­gle direc­tion, such as later win­ters. Thus, large-​scale cli­matic phe­nom­ena affect­ing Siberia are appar­ent in Lake Baikal sur­face water tem­per­a­ture data, dynam­ics result­ing from jet stream and storm track vari­abil­ity in cen­tral Asia and across the North­ern Hemisphere.

The work done is rel­e­vant, because we need to go beyond detect­ing past cli­mate vari­a­tion. We also need to know how those cli­mate vari­a­tions are actu­ally trans­lated into local ecosys­tem fluc­tu­a­tions and longer-​term local changes. See­ing how phys­i­cal dri­vers of local ecol­ogy, like water tem­per­a­ture, are in turn reflect­ing global cli­mate sys­tems will allow us to deter­mine what impor­tant short-​term eco­log­i­cal changes may take place, such as changes in lake pro­duc­tiv­ity. They also help us to fore­cast con­se­quences of cli­mate variability.

The cli­mate indices reflect alter­ations in jet stream strength and tra­jec­tory, and these dynam­ics col­lec­tively appear to fore­cast sea­sonal onset in Siberia about three months in advance, accord­ing to the study.

(Sources: Sci­enceDaily, 18.02.2011; PloS-​one, 16.02.2011)

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