As the summer heats up, air conditioners are being cranked to full blast. Once upon a time—that is, until the 1980s—the coolant gasses in these machines, which leaked into the atmosphere after units were junked, were a major threat to the ozone layer. Now manufacturers have replaced them with ozone-friendly versions. But the new coolants are still potent greenhouse gasses.
Kudzu: It’s worse than you thought. The invasive plant now covers more than 7 million acres in the United States, mostly in the Southeast but not limited to there. Besides overrunning trees as it spreads like wildfire, the vine also brings another danger: In a study in the Proceedings of the National Academy of Sciences, Jonathan Hickman sounds the alarm that kudzu could cause a spike in ozone, polluting the air.
Ozone, of course, is a good thing when it’s high in our atmosphere, blocking some of the sun’s harmful radiation. But down on the surface of the planet, ozone isn’t such a good thing. It can cause respiratory problems in people and harm plants’ ability to absorb carbon dioxide; it also is a major constituent of smog.
Kudzu’s contribution to ozone levels works like this: Like other members of the pea family, or legumes, Kudzu grabs nitrogen from the air and puts it into the soil. There microbes convert nitrogen into nitrous nitric oxide, one of the pollutants that also comes from automobile exhaust. That gas escapes from the soil and into the air, and undergoes reactions that lead to the creation of ozone [Discovery News].
Twenty-five years ago this month, British scientists announced their discovery of the ozone hole over Antarctica. That bolt from the blue spurred perhaps the best-coordinated international response to an environmental crisis to date. Now, scientists can’t help but wonder: Why didn’t the same thing happen with climate change?
Looking back on the ozone problem: Even before the discovery of the hole in the ozone layer—that blanket of three-oxygen “ozone” molecules that protect us from much of the sun’s ultraviolet radiation—researchers worried about pollutants destroying those highly reactive molecules. The British scientists’ 1985 announcement confirmed that daunting reality.
Technically a substantial thinning of the ozone layer, the ozone “hole” has been opening every spring since the 1970s, the scientists reported. Their data, collected at the Halley Research Station in Antarctica, suggested that CFCs were to blame. That’s because atmospheric conditions during the cold, dark, Antarctic winters were building stockpiles of CFCs over the South Pole [National Geographic].
America seems to be more and more linked to Asia–not just by complicated financial ties, but also by currents of air pollution that are boosting smog levels in American skies. For years scientists wondered why some rural areas in the western United States had high levels of ozone, when the areas had very little industry or automobile traffic. The answer, apparently, was blowing in the wind.
A new study, published in Nature reveals that springtime ozone levels in western North America are on the rise, because of air pollution coming in from south and east Asia.
Nitrous oxide, also known as laughing gas, might sound like a humorous substance. But here’s a sobering fact: The chemical now poses the largest man-made threat to the ozone layer, according to a study published in Science. Environmental policies, which have focused on controlling emissions of compounds such as CFCs, have largely ignored nitrous oxide. CFC levels have been falling since the 1989 adoption of the Montreal Protocol on Substances that Deplete the Ozone Layer… Meanwhile, nitrous oxide levels have been climbing as a result of increased emissions from agricultural fertilizers, biomass burning and animal waste [Nature News].
Researchers used a model to compare the potential of various gases, including laughing gas, to deplete the ozone layer, compared to a compound called CClF3, a substance with one of the greatest potentials for destroying the ozone. They found that although the threat that nitrous oxide poses to ozone is small compared to CClF3, the large-scale emissions of laughing gas mean it is the most significant of the ozone-depleting substances emitted by human-related activities today…. “This is the first time someone has dealt with nitrous oxide in isolation like this,” says atmospheric chemist Susan Solomon. “It’s one of those things that has simply been overlooked” [Nature News].
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At the bottom of the world, fluctuations in sea ice surrounding the frozen continent of Antarctica have posed a puzzle. In West Antarctica, the vast Wilkins Ice Shelf off the Antarctic peninsula appears to be headed towards a collapse. But in East Antarctica, sea ice has been expanding since the 1970s. Researchers from the British Antarctic Survey and NASA set out to determine what was going on, and quickly ruled out one possible answer: Global warming is not an illusion, they say, and Antarctica as a whole is gradually warming up, as is the world at large.
The answer to the riddle, they say, lies in a different (and almost forgotten) environmental problem: the hole in the ozone layer, which has altered weather patterns around Antarctica. These changes have drawn in warm air over the Antarctic Peninsula in West Antarctica and cooled the air above East Antarctica [New Scientist].