The ozone hole over Antarctica has remained at a staggering 12 million square miles (give or take a few thousand miles) since the early 1990's. Climate scientists have new hope though that it will start to shrink. Since the size varies due to the amounts of chemicals in the air and the temperatures, NASA's AURA satellite was used to determine how much the levels of these chemicals in the atmosphere varied each year. The data recorded has led researchers to estimate that the hole will be significantly smaller by 2040. The Montreal Protocol, which reduced emissions of dangerous chemicals is partly responsible for the decline. Scientists will continue to use satellites to keep watch on the size of the ozone hole and they hope to see its full recovery by the end of the century.