Less than a week before the International Day for the Preservation of the Ozone Layer on September 16, UN Secretary-General Ban Ki-moon has released a statement praising the success of the Montreal Protocol.

The Montreal Protocol on Substances that Deplete the Ozone Layer, signed by 197 countries in 1987, placed legally binding restrictions on the production and use of chlorofluorocarbons (CFCs) and other ozone depleting chemicals.

At the time the Montreal Protocol was signed, the earth was facing a ten-fold increase in atmospheric ozone depleting chemicals by 2050, instead ozone levels saw a four percent improvement from 2000 to 2013.

“International action on the ozone layer is a major environmental success story. This should encourage us to display the same level of urgency and unity to tackle the even greater challenge of climate change,” said Michel Jarraud, secretary-general of the World Meteorological Organization according to PBS Newshour.

Scientists warn that while the situation is improving, the hole in Earth’s ozone layer will continue to appear over the Southern Hemisphere. While CFC’s have been regulated and controlled, the chemicals released decades ago remain in the atmosphere.

The hole in Earth’s ozone layer allows more solar radiation to pass through the atmosphere. That radiation has been linked to inhibited plant growth, development of marine organisms and cataracts and skin cancer in humans.

While many are expressing hope that this success story will lead to greater international cooperation on global warming, the Montreal Protocol may, ironically, make the problem worse. MIT atmospheric scientist Susan Solomon told the Dallas Morning News that many of the chemicals used to replace CFCs contribute to greenhouse gasses and global warming. While Solomon admits that those chemicals contributions to overall greenhouse gasses is small at the moment, they are expected to make a significant contribution by 2050.