Recent changes in a remote Arctic lake are unique within the past 200,000 years
AUTOR(ES)
Axford, Yarrow
FONTE
National Academy of Sciences
RESUMO
The Arctic is currently undergoing dramatic environmental transformations, but it remains largely unknown how these changes compare with long-term natural variability. Here we present a lake sediment sequence from the Canadian Arctic that records warm periods of the past 200,000 years, including the 20th century. This record provides a perspective on recent changes in the Arctic and predates by approximately 80,000 years the oldest stratigraphically intact ice core recovered from the Greenland Ice Sheet. The early Holocene and the warmest part of the Last Interglacial (Marine Isotope Stage or MIS 5e) were the only periods of the past 200,000 years with summer temperatures comparable to or exceeding today's at this site. Paleoecological and geochemical data indicate that the past three interglacial periods were characterized by similar trajectories in temperature, lake biology, and lakewater pH, all of which tracked orbitally-driven solar insolation. In recent decades, however, the study site has deviated from this recurring natural pattern and has entered an environmental regime that is unique within the past 200 millennia.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2773966Documentos Relacionados
- Griseofulvin resistance mutation of Chinese hamster ovary cells that affects the apparent molecular weight of a congruent to 200,000-dalton protein.
- Suicide mortality in Greater London: changes during the past 25 years.
- Bacterioplankton Community Shifts in an Arctic Lake Correlate with Seasonal Changes in Organic Matter Source
- Changes in antibiotic sensitivity of staphylococci in a non-hospital population during the past 20 years.
- Sedimentary changes on the Southeastern Brazilian upper slope during the last 35,000 years