CO2 levels are highest for millions of years — and they just set a new benchmark

Scientists have recorded CO2 levels of more than 410 parts per million (ppm) for the first time since records began — and have warned that levels are only set to rise further.

Researchers at the Mauna Loa Observatory in Hawaii, which has been recording air pollution levels since 1958, said comparable levels of atmospheric carbon dioxide were last found about three million years ago.

The level stood at at 280 ppm in 1958 and, in 2013, passed 400 ppm. It has now risen to 410ppm and is unlikely to dip again.

“Its pretty depressing that it’s only a couple of years since the 400 ppm milestone was toppled,” Gavin Foster, a paleoclimate researcher at the University of Southampton told Climate Central last month.

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“These milestones are just numbers, but they give us an opportunity to pause and take stock and act as useful yard sticks for comparisons to the geological record.”

The Met Office had predicted the 410 ppm mark would be reached and passed by April in its first-ever carbon dioxide forecast earlier this year.

Carbon dioxide concentrations have skyrocketed over the past two years, according to Climate Central.

It said this was due, in part, to natural factors like El Niño, but mostly because record amounts of carbon dioxide humans are creating by burning fossil fuels.

It added that even when concentrations of carbon dioxide level off, the impacts of climate change will extend centuries into the future.

“The rate of increase will go down when emissions decrease,” Pieter Tans, an atmospheric scientist at the National Oceanic and Atmospheric Administration, said. “But carbon dioxide will still be going up, albeit more slowly. Only when emissions are cut in half will atmospheric carbon dioxide level off initially.”

The planet has already warmed 1.8°F (1°C), including a run of 627 months in a row of above-normal heat.