Mauna Loa captures milestone for carbon dioxide in the atmosphere

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Climate science reached an unhappy milestone last week. And then things went a little crazy.

Climate science reached an unhappy milestone last week. And then things went a little crazy.

One of the world’s most important sentinel sites for measuring levels of carbon dioxide in the atmosphere, in Mauna Loa, reported that levels had recently risen above the symbolically important figure of 400 parts per million, and were likely to stay that way “for the indefinite future.”

Because rising amounts of carbon dioxide, a heat-trapping gas, in the atmosphere have been linked to climate change, scientists suggest that rising above the 400-ppm line makes it even harder to prevent global temperatures from rising beyond the goal of 2 degrees Celsius agreed to in Paris. It has been millions of years since atmospheric levels of carbon dioxide have risen so high.

Some of the reaction has been alarmist. Vice Motherboard, for example, screamed, “Goodbye World: We’ve Passed the Carbon Tipping Point for Good.”

But Ralph Keeling, director of the Scripps CO2 program, who wrote the blog post announcing the news, seemed a bit taken aback by such apocalyptic headlines.

“The first step is just to stop the increase,” he said. “There’s no punting on global warming.”

He stressed that 400 ppm is “a good yardstick,” but “to call it a tipping point is incorrect.”

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