Wednesday, April 30, 2014

New paper shows prior interglacials over past 600,000 years similar to the present interglacial

A paper published today in Quaternary Science Reviews reconstructs temperatures and CO2 levels using a pollen proxy in Turkey over the past 600,000 years and shows remarkable agreement with the Arctic ice core data, with prior interglacials as warm or warmer than the present interglacial, similar vegetation, and prior interglacials with CO2 levels at or above those of the pre-industrial period. 

First graph at left is the pollen temperature proxy. Added red line shows 3 prior interglacials as warm or warmer. Third graph is CO2 levels, with most prior interglacial CO2 levels as high or higher than the pre-industrial period [red line is added]. Second graph from right is Greenland ice core temperature proxy. Last graph is solar insolation in January and June. 


Lake Van record is the longest Quaternary paleoclimate archive in the Near East.
It documents multiple glacial–interglacial cycles encompassing the last 600 ka.
The pollen data reflect high-amplitude climate shifts.
The results are compared with continental, marine and ice-core records.


Lake Van is the fourth largest terminal lake in the world (38.5°N, 43°E, volume 607 km3, area 3570 km2, maximum water depth 460 m), extending for 130 km WSW–ENE on the eastern Anatolian high plateau, Turkey. The sedimentary record of Lake Van, partly laminated, obtains a long and continuous continental sequence that covers multiple interglacial–glacial cycles. Promoted by the potential of the sedimentary sequence for reconstructing the paleoecological and paleoclimate development of the Near East, a deep drilling operation was carried out in 2010 supported by the International Continental Scientific Drilling Program (ICDP). The 219 m long continental pollen record presented here is based on a well-dated composite profile drilled on the so-called Ahlat Ridge in water depth of 360 m encompassing the last 600,000 years. It is the longest continuous continental pollen record of the Quaternary in the entire Near East and central Asia obtained to date. The glacial–interglacial cycles and pronounced interstadials are clearly reflected in the vegetation development based on millennial-scale time resolution. In general, the glacial/stadial vegetation is characterized by dwarf-shrub steppe and desert steppe, whereas the climax vegetation of past interglacials can be described as oak steppe-forest similar to the present interglacial in this sensitive semi-arid region between the Black, Caspian, and Mediterranean Seas. By comparing the Lake Van pollen record with other western Asian and southern European long continental pollen sequences as well as marine and ice-core records, the regional variability of the climate signals is also discussed.

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