An Environmental Victory (and Cautionary Tale)

For once, the news on the environmental front isn’t just good, it could be taken as a point of pride. This week, scientists announced that the infamous ozone hole over Antarctica is starting to heal. In 1987, the world agreed to phase out chemicals that were destroying a layer of gas in the upper atmosphere that shields the planet from damaging ultraviolet light. This week, in the journal Science, researchers said they’re finally starting to detect results. In September, the hole had shrunk by 1.5 million square miles from its peak in 2000.

There is a sobering side to this story, though: The chemicals responsible for the ozone problem break down in the atmosphere much more quickly than carbon dioxide connected to global warming does. That’s why the same MIT atmospheric chemist who announced the ozone improvement also argues that climate change caused by burning fossil fuels is essentially “irreversible.” For scientists, optimism and pessimism have to be tempered by the realities of chemistry and reaction rates.