During the last years and decades, there has been a realization that human activities have altered the naturally occurring concentration of ozone, leading to stratospheric ozone loss and 'ozone hole' over Antarctica, global warming and climate change.

In order to investigate and understand the chemical and physical processes that anthropogenic gas emissions have on the atmosphere, a global atmospheric observation platform, ENVISAT has been provided by ESA. On this platform are three instruments - SCIAMACHY, MIPAS and GOMOS that provide information on a larger family of trace gas constituents which play an important role in atmospheric chemistry and in climate change issues.