Discussions of potential climate change have tended to focus on past and possible future changes in surface temperature. These discussions ignore the fact that climate processes occur in the troposphere, and that any assessment of climate variability and change must consider both the surface and the troposphere.
Our current theoretical understanding of greenhouse warming indicates that human emissions of greenhouse gases should warm the troposphere faster than they warm the surface. However, satellite-based measurements of tropospheric temperature indicate that since 1979 the troposphere has warmed at a rate that is significantly slower than the rate of surface warming. Climate models do not simulate this phenomenon, nor can it be explained by natural climate variability, i.e., the effects of volcanic eruptions or El Niño. The disparity between observations and theory-based projections of the rates of tropospheric warming is an indication of our limited understanding of the climate system and raises serious question about our ability to project future climate. However, as is always the case in scientific research, more weight must be given to measured data than to theoretical calculations.