We have developed a new technique of a posteriori calibration of overlapping multi-satellite records and applied it to Microwave Sounding Unit (MSU) observations, making them suitable for climate change studies. This new technique was used to produce the latitudinal distribution of brightness temperature trends from the microwave satellite data (MSU Channel 2) for the period 1978-2004, and we evaluated the sensitivity of the global trend estimates to choice of reference instrument and other factors. By comparing the MSU measurements to the observed surface trends and to a set of GFDL climate model simulations, we find that while the global average trends for the surface and the troposphere are the same, the latitudinal distribution of differences between trends is also interesting and shows important climate system behavior. The latitudinal distributions of climate model trends at the surface and the troposphere are virtually the same as the observations, giving us more confidence in both.