Via P Gosselin above 29. March 2022
ONE New article published in the MDPI open access publication examines seven prominent global and hemispheric temperature reconstructions over the past 2000 years (T2k).
The analysis performed by the authors found that some reconstructions “disparate from each other at some intervals by more than 0.5°C” while some show pre-industrial climate variability. negligible (“hockey sticks”).
Indications of change would suggest that natural factors play a larger role than those that assume the climate has not changed in the past 2000 years.
Abstract: The global average annual temperature has increased by more than 1°C over the past 150 years, as recorded by thermometer measurements. Unfortunately, such observational data are not available for the pre-industrial period of the Common Era (CE), in which climate development was reconstructed using a variety of paleontological proxies. In this analysis, we compared seven prominent global and hemispheric temperature reconstructions over the past 2000 years (T2k) that differ in some segments by more than 0.5°C. While some T2k shows negligible pre-industrial climate variability (“hockey sticks”), others show significant temperature fluctuations. We discuss possible sources of errors and highlight three criteria that should be considered to increase the quality and stability of future T2k reconstructions. The temperature proxy sequence should be thoroughly validated with respect to (1) reproducibility, (2) seasonal stability, and (3) representativeness by aspect. T2k represents the primary calibration data for climate models. These models need to first reproduce pre-industrial climate histories that have been reconstructed before being validated and cleared for future climate projections. It will not be possible to accurately attribute modern warming to anthropogenic and natural causes until T2k composites are stable and truly represent a well-defined region and season. clear. The disparity between the different T2k reconstructions directly leads to a major challenge regarding the political interpretation of the climate change risk profile. As a general rule, the larger/small the pre-industrial temperature change is, the higher/lower the natural contribution to the current warm period (CWP), thereby reducing/increasing the amount of greenhouse gases. HAVE2 climate sensitivity and expected warming until 2100.
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