This warning comes as recent evidence suggests that a thinning ozone layer may have driven Earth’s largest mass extinction 252 million years ago.
The ozone layer that protects people from the sun’s ultraviolet radiation is not recovering over most highly populated regions, scientists warned on Tuesday.
The greatest losses in ozone occurred over Antarctica but the hole there has been closing since the chemicals causing the problem were banned by the Montreal protocol. But the ozone layer wraps the entire Earth and new research has revealed it is thinning in the lower stratosphere over the non-polar areas.
Reduced protection from cancer-causing UV rays is especially concerning towards the equator, where sunlight is stronger and billions of people live. The reason for the falling ozone at lower latitudes is not known, though scientists suspect a chemical used in paint stripper and a change in atmospheric circulation caused by climate change.
The cause of the decline is unknown but might be the result of global warming. Ozone is produced by chemical reactions in the atmosphere over the tropics and then distributed towards the poles world by large air circulation currents. But warming trends could be strengthening these currents, moving more ozone to the poles and leaving less at lower latitudes.
Another suspect is so-called “very short lived substances” (VSLS) – industrial chemicals that destroy ozone. It was thought they broke down too quickly to reach the stratosphere, but that may need to be re-examined.
The protections afforded by the ozone layer are important.
Hailed as an example of how concerted global action can help solve a planetary crisis, a new study conducted by NASA scientists documented the first direct evidence that an international effort to ban chlorofluorocarbons (CFCs) has led to the recovery of the Antarctic ozone hole.
Published in the journal Geophysical Research Letterson Thursday, the study uses satellite observations to demonstrate that the decline in atmospheric chlorine that resulted from the implementation of the Montreal Protocol, enacted in 1989, has led to “about 20 percent less ozone depletion during the Antarctic winter than there was in 2005—the first year that measurements of chlorine and ozone during the Antarctic winter were made by NASA’s Aura satellite.”
“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,” Susan Strahan, an atmospheric scientist from NASA’s Goddard Space Flight Center and one of the study’s lead authors, said in a statement.
Responding to the study’s results on Twitter, Greenpeace called for the success of Montreal Protocol to be used as a model for tackling the climate crisis.
“We’ve stopped harmful pollutants before and nature has healed itself,” the group observed. “Let’s cut carbon emissions now and allow nature to heal itself again.”