Remember the giant hole in the Earth's ozone layer? Scientists say it's shrinking a little, thanks in part to the elimination of chlorofluorocarbons, or CFCs, beginning in the 1980s.
For the first time in 35 years, scientists have confirmed a statistically significant increase in the amount of ozone, which shields us from skin cancer and protects crops from sun damage.
NASA scientist Paul A. Newman, who co-chairs an ozone assessment by 300 scientists that takes place once every four years, says that from 2000 to 2013, ozone levels climbed by 4 percent in mid-northern latitudes at about 30 miles up, at the upper edge of the stratosphere.
"It's a victory for diplomacy and for science and for the fact that we were able to work together," says chemist Mario Molina, who won a Nobel Prize for his research into the ozone layer.
"It was in the 1970s that scientists first realized chlorofluorocarbons (CFCs) had worn the ozone layer thin above Antarctica. Studies have shown that, left unchecked, ozone destruction could cause higher rates of skin cancer, disrupt plant growth and destabilize the aquatic food chain thanks to an increase in harmful ultraviolet rays.
"Fortunately, the world's policymakers were proactive about environmental problems back then. Leaders agreed in 1987 to the Montreal Protocol, which phased out CFCs.
"At the time, industry objected, saying the science was speculative and that regulation would be costly and lead to lost jobs."
According to The Boston Globe: "The United Nations calculated in an earlier report that without the pact, by 2030 there would have been an extra 2 million skin cancer cases a year around the world."
"Many of these early signs of ozone improvements are due to decades of work and contributions by NASA and NOAA instruments and scientists," says Newman, chief scientist for atmospheres at NASA's Goddard Space Flight Center in Greenbelt, Md.
According to NASA, ozone depleting substances are also powerful greenhouse gases, so the Montreal Protocol helped slow the growth of greenhouse gases at the same time it was stopping ozone depletion.
Even so, many CFC substitutes are themselves heat-trapping substances, so "these substitutes could offset the climate gains achieved by the Montreal Protocol in the future," Newman noted.
Previously, the Environmental Protection Agency reported a similar success story with acid rain, which has decreased thanks in part to a cap-and-trade system added to the Clean Air Act by President George H.W. Bush. That change is credited with lowering sulfur dioxide emissions beginning in the 1990s, according to Forbes.