Atmospheric carbon levels peak at level not seen for 4 million years


Carbon dioxide in the atmosphere peaked more than 50% higher than pre-industrial levels in May, comparable to levels observed around 4 million years ago, according to the National Oceanic and Atmospheric Administration (NOAA).

Carbon dioxide recorded at NOAA’s Mauna Loa Atmospheric Baseline Observatory peaked for 2022 in May at 421 parts per million (ppm), up 1.8 ppm from 2021. A monthly average of 420.78 ppm was calculated by scientists at the Scripps Institution of Oceanography at the University of California San Diego.

“The science is irrefutable,” said NOAA Administrator Rick Spinrad. “Humans are altering our climate in ways that our economy and our infrastructure must adapt to.”

For about 6,000 years prior to the Industrial Revolution, carbon levels were consistently around 280 ppm. Humans have produced an estimated 1.5 trillion tonnes of carbon dioxide pollution since then, the most of which will continue to warm the atmosphere for thousands of years.

Carbon levels are presently comparable to the Pliocene Climatic Optimum, which occurred between 4.1 and 4.5 million years ago, when atmospheric carbon levels were around 400 ppm. Sea levels were between 5 and 25 meters higher than they are now, high enough to drown several of the world’s greatest modern cities.

Temperatures were 7 degrees Fahrenheit hotter than they are now, and research show that vast forests once filled today’s Arctic tundra.

Despite decades of efforts, the international community has not been able to significantly decrease carbon emissions, let alone reverse annual rises in atmospheric carbon levels.

“It’s depressing that we’ve lacked the collective will power to slow the relentless rise in carbon dioxide,” said geochemist Ralph Keeling. “Fossil-fuel use may no longer be accelerating, but we are still racing at top speed towards a global catastrophe,” he added.

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