The hole won’t completely close for at least 30 years at the earliest but is a little less almost every year, says Susan Solomon, an atmospheric chemist at the Massachusetts Institute of Technology and lead author of the study published Thursday in the journal Science.
"It’s a big surprise,” she says. “I didn’t think it (the healing) would be this early.”
The hole is actually a thinning in the high-altitude ozone layer because of past human use of chlorofluorocarbons in refrigeration, air conditioning and aerosol sprays.
In the late 1980s, 196 countries signed the Montreal Protocol, a treaty that limited worldwide production of CFCs.
The ozone layer blocks potentially harmful ultraviolet energy from reaching Earth’s surface. Thinning in the layer is linked to increased rates of skin cancer and eye cataracts.
The discovery of the healing shows that global attempts to improve Earth’s environment can work, providing a template for how humanity could tackle the exponentially larger issue of climate change, Solomon says.