Hindu: Global warming will set back the recovery of the ozone layer of the earth’s atmosphere, warns a NASA study. Previous studies have shown that while the build up of greenhouse gases makes it warmer in the troposphere, up to 10 km high from sea level, these gases actually cool the upper stratosphere, between 30 to 50 km high. This cooling slows the chemical reactions that deplete ozone in the upper stratosphere and allows natural ozone production in that region to outpace …