The sole purpose of CCS is to curb climate change. The primary cause of global warming is the release of CO2 from the use of fossil fuels that have been in the ground for millennia; CCS prevents the escape of CO2 and puts the carbon back into the ground. Captured CO2 may also be used for some industrial purposes, and this can be of commercial value, but although it may sometimes reduce the release of greenhouse gases the use of CO2 is only rarely as effective as permanent storage.