Carbon-dioxide concentrations in Earth’s atmosphere have reached their highest level in four million years, according to the Economist.
On May 4th, the carbon dioxide concentrations around Hawaii’s Mauna Loa Observatory were at 400 parts per million (ppm), with researchers expecting the figure to increase in the next few days.
The last time concentrations were as high on Earth was in the Pliocene epoch, four million years ago.
There have been concentrations of carbon-dioxide exceeding 400ppm elsewhere in the world, like readings taken over the Arctic Ocean in 2012, but they were considered exceptional. Mauna Loa is considered to be the benchmark due to Hawaii’s distance from large populations of humans, while a lot of Europe and North America’s pollution travels to the Arctic.
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