The hole in the ozone layer over the Antarctic was the second smallest in the last two decades, data from NASA and the National Oceanic and Atmospheric Administration (NOAA) satellites shows. This year also showed an improvement in the concentration of ozone in the region, with the minimum level recorded hitting its second highest level in twenty years. However, the reason appears to be a change to warmer temperatures in the Antarctic lower stratosphere, and experts warn that the improvement may not last. "The ozone hole mainly is caused by chlorine from human-produced chemicals, and these chlorine levels are...