South Pole final place on Earth to surpass 400 ppm milestone

Carbon dioxide crossed the 400 parts per million (ppm) threshold at the South Pole on 23 May for the first time in 4 million years, marking an unfortunate milestone in the upward CO2 trend on our planet.

The honeymoon following last year’s historic climate change agreement reached at the UN talks in Paris is officially over: the carbon dioxide observing station in the South Pole cleared the 400 ppm threshold last month. This is the first time in 4 million years that such high CO2 levels were recorded in the far reaches of Antarctica.

While last year’s global CO2 averaged reached 399 ppm – with much of it originating in the northern hemisphere where much of the world’s population lives – levels remained lower in the South Pole because there is a lag in how carbon dioxide moves around the atmosphere, explains an article in the Guardian.

But no more.

“The far southern hemisphere was the last place on earth where CO2 had not yet reached this mark,” said Pieter Tans, the lead scientist of NOAA’s Global Greenhouse Gas Reference Network. “Global CO2 levels will not return to values below 400 ppm in our lifetimes, and almost certainly for much longer.”

Tans and his colleagues have even more pessimistic news. According to a NOAA statement, with last year’s average global levels already so high, the levels for 2016 will almost certainly surpass 400 pm. “The only question is whether the lowest month for 2016 will also remain above 400.”

The scientists also found that the annual rate of increase appears to be accelerating. For instance, last year was the fourth consecutive year that CO2 grew more than 2 ppm, and all signs indicate that this year will be the fifth.

“We know from abundant and solid evidence that the CO2 increase is caused entirely by human activities,” Tans said. “Since emissions from fossil fuel burning have been at a record high during the last several years, the rate of CO2 increase has also been at a record high.”

As the Guardian reports, passing the 400 ppm threshold is a symbolic but important reminder of how human activities are shaping our planet in damaging ways. Sea levels have risen around 30 centimetres in the past 120 years, while Arctic sea has dwindled 13.4 per cent per decade since the 1970s. Rising ocean temperatures are destroying coral reefs, while increasing atmospheric temperatures are resulting in extreme weather events such as droughts, heat waves and flooding.

And the biggest concern is that some of the fossil fuel burned in recent years will remain in the atmosphere for thousands of years. As Tans told the Guardian: “Just because we have an agreement doesn’t mean the problem (of climate change) is solved.


Image credit: Liam Quinn, flickr / Creative Commons


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