Global and hemispheric temperature trends: uncertainties related to inadequate spatial sampling

Abstract

Results imply that the errors associated with century-scale trends of temperature are probably an order of magnitude smaller than the observed global warming of nearly 0.5°C per 100 years since the late nineteenth century. The errors in estimates of decadal temperature trends are found to be large relative to century-scale trends and are unreliable during the nineteenth and early twentieth centuries. Even during the recent decade of the 1980s, the area-averaging techniques used in some analyses could be improved by addressing the over-sampling of Northern Hemisphere (especially over land) relative to the rest of the globe. Otherwise, significant positive biases are likely during the 1980s. These biases may have contributed to the reported differences between in situ surface and space-based temperatures during the 1980s. -from Authors