Saturday, February 15, 2014

New paper finds Colorado was warmer than the present during the last interglacial

A paper published today in Quaternary Research reconstructs temperatures in Snowmass Village, Colorado during the last [Eemian] interglacial and finds minimum & maximum temperatures were higher around 82,000 years ago than during modern times. The paper adds to many other peer reviewed publications finding the last interglacial was warmer than the present, e.g. Greenland was 8C warmer, and sea levels up to 31 feet higher than the present, and there is no evidence to suggest the current interglacial is any different. 

Maximum and minimum temperatures were higher than modern times during late MIS 5a around 82,000 years ago. 
Organic-rich lake sediments from a trench exposed at Ziegler Reservoir fossil site near Snowmass Village, Colorado yielded a sequence of 27 insect fossil assemblages, spanning the time interval from about 125 to 77 ka. The assemblages appear to represent MIS 5e, 5c, 5b, and 5a. A total of 99 taxa were identified, mostly beetles. The fossils represent the oldest known Pleistocene insect faunas from high elevation in the Rocky Mountains, and document a series of climatic oscillations from full interglacial to stadial and interstadial environments, accompanied by changes in regional biological communities. The MIS 5e fauna indicates summer temperatures similar to modern values, with winter temperatures 5–7 °C cooler than today. Regional climates cooled somewhat by MIS 5c, and during MIS 5b summer temperatures were 5–6 °C colder than modern values. Summer temperatures recovered to near-modern levels during early MIS 5a, and cooled by 1–2 °C at its end, although winter temperatures were apparently above modern levels. The indication of milder but wetter winters, strengthened by the inclusion of species found today only in the Pacific Northwest region, suggests conditions that may have led to increased snowpack at high elevations in this part of the Southern Rockies, linked with the onset of MIS 4 glaciation.

No comments:

Post a Comment