Temperatures High and Low

摘要

Satellite measurements of atmospheric temperatures have been available since 1979 through retrievals from Microwave Sounding Units (MSUs). These measurements show virtually no warming trend in the lower troposphere, the layer from about 1 to 5 km above Earth's surface. In contrast, measurements taken in situ at Earth's surface indicate a globally averaged warming of between 0.3° and 0.4℃ over the same period. Papers in this issue by Santer et al. (1, p. 1227) and Gaffen et al. (2, p. 1242) use a combination of observations and model simulations to throw further light on these trends and bring a partial reconciliation.