What do climate change, ultraviolet radiation and ozone have in common?
Scientists are positing a possible link between the three based on a new study. The logic goes something like this: Summer thunderstorms in the U.S. inject water vapor much higher in the atmosphere than anyone realized. The result is a “cascade of chemical reactions,” as the journal Nature put it, that may, coupled with global warming, punch more holes in the ozone layer. More holes in the ozone layer means more ultraviolet radiation hitting Earth. More ultraviolet radiation hitting Earth means more skin cancer.
The string of observations and predictions was touched off by an accidental discovery by Harvard University atmospheric chemist James Anderson and a team of researchers as they studied the origins of cirrus clouds—wispy affairs that form at high altitudes and trap heat, contributing to the greenhouse effect. What they found was that, rather than injecting vapor eight miles or so upward, about half the storms they studied threw it from nine to 12 miles up—smack into the middle of the part of the stratosphere that contains about 20 percent of the total stratospheric ozone, the scientists reported in the journal Science on July 26.
“We were shocked,” Anderson told Nature. “Standard, run-of-the-mill Midwestern thunderstorms are far more capable of injecting water vapor into the stratosphere than we once thought.”
Anderson helped raise the alarm about the holes in the ozone layer over the Antarctic and the Arctic, leading to the Montreal Protocol, which reduced the use of chlorofluorocarbons (CFCs) in everything from aerosol cans to refrigerators. He told National Geographic that summer storms could create some of the same conditions as CFCs once did.
"We essentially have the chemistry that's present in the Arctic that is clearly very potent for destroying ozone," Anderson told National Geographic, meaning that conditions could be ripe for ozone-layer destruction at that level of the stratosphere. However, others said there are a lot of ifs.
“I’m not at all surprised that this happens,” said Andrew Dessler, an atmospheric scientist at Texas A&M University in College Station. “But I think a challenge is really going to be quantifying all aspects of the problem.”
Variables such as how frequently the water vapor is injected into the atmosphere and how often that leads to the water-chlorine reactions that could reduce the ozone need further study, he said, quoted in Nature. Similarly, Massachusetts Institute of Technology climatologist Kerry Emanuel said, the study draws attention to the need to know how storms will respond to climate change.
Skeptical or not, the scientists concurred in saying that the findings could highlight a potential problem. However such issues are many steps removed from the situations that Indian country is confronting at the forefront of climate change.
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