A gaping wound in Earth's atmosphere is healing. Since 2000, the average size of the Antarctic ozone hole in September has shrunk by about 4.5 million square kilometers, an area larger than India, researchers report online June 30 in Science. While the hole won't close completely until at least midcentury, the researchers say the results are a testament to the Montreal Protocol. Implemented in 1989, it banned ozone-depleting chemicals called chlorofluorocarbons worldwide. Tracking the ozone layer's recovery is tricky because natural phenomena such as weather can alter the size of the hole.
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