The climate of Europe in recent centuries in the context of the climate of mid to high latitude northern hemisphere from borehole temperature logs

Abstract

I present results from inversions for ground surface temperature histories reconstructed from deep borehole temperatures in Europe in the context of mid to high latitude Northern Hemisphere data. Precise deep borehole temperature logs provide information about the average warming and preceding colder period and average timing of the onset and magnitude of the recent warm period. Analysis of the borehole temperature-depth data from the mid to high latitude Northern Hemisphere using a simple ramp function model indicates that the timing of the onset of warming and its amplitude varies spatially. This large spatial variation explains large standard deviation of the average ground surface temperature histories derived from stack of individual ground surface temperature reconstructions from borehole temperature logs. Such averaged continental and N Hemisphere histories are commonly used to compare with other proxy. Central and Northern European borehole temperatures point to high ground temperature warming (0.5°-2°C) in recent two centuries. This warming is generally less than in northern parts of North America including high Arctic and less than most of Asia (1°-3°C). Timing of the onset of Central European recent warm period is circa 100-150 years and is compatible with that in the northern N. America and especially western Canada and Alaska. It is more than 200 years for the start of the recent warming period in south-central N. America and in Asia. Warming signal from Earth's subsurface is apparent for the Polish borehole temperature logs. Large warming observed in central-northern Europe is the main feature seen from the available european data. © Springer Science + Business Media B.V. 2010.