Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia
Composite NH temperature reconstructions & published NH reconstructions.
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Proxy-based reconstructions of hemispheric
and global surface temperature variations
over the past two millennia
Proceedings of the National Academy of Sciences
Vol. 105, No. 36, pp. 13252-13257, September 9, 2008. doi:10.1073/pnas.0805721105
Michael E. Mann1, Zhihua Zhang1, Malcolm K. Hughes2, Raymond S. Bradley3, Sonya K. Miller1, Scott Rutherford4, and Fenbiao Ni 2.
1 Department of Meteorology and Earth and Environmental Systems Institute,
Pennsylvania State University, University Park, PA 16802
Following the suggestions of a recent National Research Council report [NRC (National Research Council) (2006) Surface Temperature Reconstructions for the Last 2,000 Years (Natl Acad Press, Washington, DC).], we reconstruct surface temperature at hemispheric and global scale for much of the last 2,000 years using a greatly expanded set of proxy data for decadal-to-centennial climate changes, recently updated instrumental data, and complementary methods that have been thoroughly tested and validated with model simulation experiments. Our results extend previous conclusions that recent Northern Hemisphere surface temperature increases are likely anomalous in a long-term context. Recent warmth appears anomalous for at least the past 1,300 years whether or not tree-ring data are used. If tree-ring data are used, the conclusion can be extended to at least the past 1,700 years, but with additional strong caveats. The reconstructed amplitude of change over past centuries is greater than hitherto reported, with somewhat greater Medieval warmth in the Northern Hemisphere, albeit still not reaching recent levels.
Download data from the WDC Paleo archive:
Compressed archive files containing:
CPS Temperature Reconstructions
EIV Temperature Reconstructions
Original Proxy Data
Infilled Proxy Data
Proxy Data Matrix
Reconstruction and Data Processing Source Code
These data are also included in the NOAA Paleoclimatology Reconstructions Network, available in columnar Text, Excel 2007, and netCDF formats.
To read or view the full study, please visit the PNAS website.
It was published in Proceedings of the National Academy of Sciences, Vol. 105, No. 36, pp. 13252-13257, September 9, 2008. doi:10.1073/pnas.0805721105
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