New 3-D simulation filters out natural variation in long-term trend
Ozone Hole Watch/NASA
A gaping wound in Earth's atmosphere is definitively 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 success of the Montreal Protocol. That international treaty, implemented in 1989, banned ozone-depleting chemicals called chlorofluorocarbons worldwide.
Ozone helps shield life on Earth from hazardous ultraviolet radiation. Tracking the ozone layer’s recovery process is tricky because natural phenomena such as volcanic eruptions and weather variations can alter the size of the ozone hole. While some earlier studies suggested that the ozone had already begun healing (