Evidence of global warming observed in arctic lakes

Sediments at the bottom of lakes are good indicators of biological activity through the ages because organisms living in polar regions are very sensitive to the slightest variation in temperature.

An international study focusing on the polar regions shows that climatic changes are at the origin of an ecological reorganization and a change of species which would have started 150 years ago.

The study was conducted by 26 researchers who studied 55 lakes located in Canada,
Russia, Spitsbergen (Norway) and Lapland (Finland). The changes appear as much in the composition of the species as in their diversity, and the variation is greater in the more northern regions. This observation is corroborated by climate models which show that global warming is more accentuated at the level of the poles. The impact of human activity cannot be the cause of these variations. In fact, unlike the temperate regions, there is very little agriculture in these regions, apart from a few herds of reindeer and caribou. The polar regions suffer from precipitation containing
heavy metals, acidic molecules and nutrients. This phenomenon is largely confined to the second half of the twentieth century, which is very much later than the beginning of the reorganization observed in this study.

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- Teacher. Atte Korhola, climate change specialist,
Coordinator of CHILL-10,000.
Department of Biology and Environmental Sciences, University of
65 Mailbox (Viikinkaari 1), FIN-00014 University of Helsinki, Finland
- tel: +358 9 191 57 840 - email: reached.korhola@helsinki.fi
Sources: Smol et al. (2005) Climate-driven diet shifts in the biological
communities of artic lakes, PNAS, early edition February
Editor: Marie Aronson

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