LOS ANGELES -- NASA scientists this week published a study reporting that the ozone layer over the Arctic fell to unprecedented low levels over the winter and spring of 2011.
Although industry and scientists around the world came together to stop the release of new ozone-destroying CFCs (chlorofluorocarbons) in the '90s, the CFCs that had already been released into the atmosphere have a long life, according to atmospheric scientists Michelle Santee and Nathaniel Livesey, two of the co-authors of the new study. It will be another 50 or so years before the level of CFCs in the stratosphere starts noticeably decreasing.
Scientists are not surprised that the ozone hole continues to show up in Antarctica. But a new hole emerging in the Arctic? That's troubling.
What happened in the Arctic is that the temperature in the stratosphere stayed colder for longer in 2011, and CFCs break down ozone faster when the stratosphere is colder.
"The challenge facing the scientific community is to try to tease out why this winter was so much colder," said Livesey in an interview with the Los Angeles Times.
Although climate change is causing warmer temperatures on Earth's surface, Santee said, it appears to be causing colder temperatures in the stratosphere. Scientists are continuing to investigate how the two phenomena are linked, she told the Times.
Their study was published Sunday in the journal Nature.
The ozone layer protects life from the sun's harmful ultraviolet radiation. It is essential to the makeup of our stratosphere.
"I don't want to convey a sense of alarm about the specific health consequences of this Arctic winter," Santee said. "The ozone layer was low only for a few weeks, so not that huge a population was exposed to harmful levels of UV."
She added, however: "The thinning ozone over the densely populated northern and middle latitudes is a concern if we see a thinning in the future."
By DEBORAH NETBURN
Los Angeles Times