In 1987, the nations of the world came together to save the planet in part by banning chemicals known as chlorofluorocarbons (CFCs). Now, three decades later, a NASA satellite has confirmed those measures were successful.

That pact in 1987 was the Montreal Protocol. It came about as a response to the discovery two years prior in 1985 of a hole in the ozone over the Antarctic. The result of this treaty was to phase out the use of CFCs, seen in things like aerosols and refrigerants.

A new study published in the journal Geophysical Research Letters shows the fruits of this treaty. Using data from NASA’s Aura satellite, scientists have discovered that there has been 20 percent less ozone depletion in the Antarctic since 2005.

"We see very clearly that chlorine from CFCs is going down in the ozone hole, and that less ozone depletion is occurring because of it," lead author Susan Strahan from NASA's Goddard Space Flight Center in Maryland said in a statement.

Every September an ozone hole forms above the Antarctic as the Southern Hemisphere’s winter arrives. This is because the Sun’s rays allow chlorine and bromine, which primarily come from CFCs, to react with the ozone.

Using the Microwave Limb Sounder (MLS) on the Aura satellite, scientists in this study were able to look at how ozone levels have changed compared to chemicals in the atmosphere year to year. While we’ve seen the ozone loss decreasing before since the CFC ban was introduced, this study is the first to show it is the direct result of declining CFCs.

"All of this is evidence that the Montreal Protocol is working," the team wrote in their paper.

This conclusion was drawn by studying the region in mid-October, when the chlorine had been converted to hydrochloric acid. By measuring how this compared to nitrous oxide, which behaves like CFCs but is not declining, the team were able to find that chlorine levels were declining by about 0.8 percent annually on average.

And that’s been enough to decrease ozone depletion in winter months. CFCs can take 50 to 100 years to disappear completely, so the progress is quite slow. It might not be until 2060, or even as late as 2080, that the ozone hole has gone completely.

But the Montreal Protocol is a clear example of how the world can come together to solve environmental issues. Gosh, if only there was another example of how that would be useful today.