Global warming: Evidence from satellite observations

Observations made in Channel 2 (53.74 GHz) of the Microwave Sounding Unit ( MSU) radiometer, flown onboard sequential, sun-synchronous, polar-orbiting NOAA operational satellites, indicate that the mean temperature of the atmo sphere over the globe increased during the period 1980 to 1999. In this stu dy, we have minimized systematic errors in the time series introduced by sa tellite orbital drift in an objective manner. This is done with the help of the onboard warm-blackbody temperature, which is used in the calibration o f the MSU radiometer. The corrected MSU Channel 2 observations of the NOAA satellite series reveal that the vertically-weighted global-mean temperatur e of the atmosphere, with a peak weight near the mid troposphere, warmed at the rate of 0.13+/-0.05 Kdecade(-1) during 1980 to 1999. The global warmin g deduced from conventional meteorological data that have been corrected fo r urbanization effects agrees reasonably with this satellite-deduced result .