Ozone depletion
Estimates of how quickly the ozone layer will regenerate vary by about two decades. NASA estimated in 2006, that it will take to 2068 for the ozone layer in Antarctica to recover to the level before human-induced thinning.  According to the World Meteorological Organization, the state of the ozone layer over Antarctica will not change noticeably in the next twenty years. The state before 1980 will be reached between 2060 and 2075, 25 years later than predicted in 2002. Over the Arctic, there will be bigger losses in ozone over the next fifteen years, esp. in cold winters. For the Arctic regions, the state before 1980 will be reached around 2050.