First, direct observational evidence of a change in the Earth’s greenhouse effect between 1970 and 1997. “Previous studies in this area have depended on theoretical simulations because of the lack of data. However the Imperial team reached their
conclusions after analysing data collected by two different earth-orbiting spacecraft, in 1970 and 1997.

Comparison between the two data sets has unequivocally established that significant changes in greenhouse gas emissions from the Earth have
caused the change to the planet’s greenhouse effect over this time period.” EurekAlert!