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Millennial-scale temperature variations in North America during the Holocene

3000 Years Before Present July Temperature Reconstruction
July Temperature Reconstruction,
3000 Years Before Present.

Millennial-scale temperature variations in North America during the Holocene

Journal of Geophysical Research
Vol. 111, D09102, doi:10.1029/2005JD006031, May 2006.

A. E. Viau1, K. Gajewski1, M. C. Sawada1, and P. Fines1,2

1 Laboratory for Paleoclimatology and Climatology, Department of Geography, University of Ottawa, Ottawa, Ontario, Canada.
2 Department of Mathematics and Statistics, University of Ottawa, Ottawa, Ontario, Canada.
A mean continental July temperature reconstruction based on pollen records from across North America quantifies temperature variations of several timescales for the past 14,000 cal yr BP. In North America, temperatures increased nearly 4°C during the late glacial, reaching maximum values between 6000 and 3000 cal yr BP, after which mean July temperatures decreased. Superimposed on this orbital-scale trend are millennial-scale temperature variations that appear coherent in structure and frequency with high resolution ice, marine and other terrestrial paleoclimate records of the Holocene. During the Holocene, climate in North America appears to have varied periodically every ~1100 years rather than the ~1500 year cycle found during the last glacial period. Coherence at frequencies between 900 and 1100 years between land, ice, and ocean records suggests a common forcing associated with widespread surface impacts during the Holocene. These results provide important insight to the global warming debate, as the observed twentieth century temperature increase appears unprecedented compared to our mean North American temperature reconstruction of the past 14,000 years.
Download data from the WDC Paleo archive:
North American July Temperature Reconstructions, Text or Excel format.
July Temperature Grids in ArcGIS format (48MB .zip file).

To read or view the full study, please visit the AGU website.
It was published in Journal of Geophysical Research, Vol. 111, D09102, May 2006, doi:10.1029/2005JD006031.
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