Evidence for influence of anthropogenic surface processes on lower tropospheric and surface temperature trends



In de Laat and Maurellis (2004), a new framework was introduced in the form of a spatial-thresholding trend technique for analyzing the correlation between anthropogenic surface processes (e.g. changes in land use, albedo, soil moisture, groundwater levels, solar absorption by soot or energy consumption) and lower tropospheric and surface temperature trends for the period 1979–2001. In situ measured surface and satellite-measured lower tropospheric temperature trends were shown to be higher in the vicinity of industrialized regions, while such higher trends were not found in enhanced greenhouse gas (GHG) climate model simulations of temperature. It was suggested that surface and lower tropospheric temperature trends appeared to be influenced by anthropogenic non-GHG processes on the earth's surface.

In this paper, we verify the robustness of the thresholding technique and confirm our earlier conclusions on the basis of an extended analysis and two additional data sets. We confirm the presence of a temperature change–industrialization correlation by analyzing the data with an additional statistical method and further confirm the absence of the above correlation in climate model simulations of enhanced GHG warming. Our findings thus provide an important test of climate model performance on regional scales.

These findings suggest that over the last two decades non-GHG anthropogenic processes have also contributed significantly to surface temperature changes. We identify one process that potentially could contribute to the observed temperature patterns, although there certainly may be other processes involved. Copyright © 2006 Royal Meteorological Society.