There’s more CO2 in the atmosphere than ever in 3 million years

Brace yourself for more bad news: the last time there was so much CO2 in the atmosphere was around 3 million years ago.

That’s according to a team of scientists who have reached this conclusion after running computer simulations of climate change, the size of ice sheets and carbon cycles over the past 3 million years. Their results, they explain in a study, “suggest that the current CO2 concentration is unprecedented over the past 3 million years.”

Global mean temperatures, they add, never exceeded preindustrial levels by more than 2 degrees Celsius during that time period. Meanwhile, at current emission rates the planet’s climate would move beyond that 2 degrees Celsius limit within half a century.

“We know from the analysis of sediments on the bottom of our seas about past ocean temperatures and ice volumes, but so far the role of CO2 changes in shaping the glacial cycles has not been fully understood,” says Matteo Willeit, the study’s lead author, from the Potsdam Institute for Climate Impact Research.

“It is a breakthrough that we can now show in computer simulations that changes in CO2 levels were a main driver of the ice ages, together with variations of how the Earth’s orbits around the sun, the so-called Milankovitch cycles,” Willeit adds. “These are actually not just simulations: we compared our results with the hard data from the deep sea, and they prove to be in good agreement. Our results imply a strong sensitivity of the Earth system to relatively small variations in atmospheric CO2. As fascinating as this is, it is also worrying.”

These findings by the researchers are in with results from a myriad of other studies that indicate that our wanton CO2 emissions may well be pushing the planet’s climate beyond a point of no return with catastrophic consequences for life on Earth as we know it.

“It seems we’re now pushing our home planet beyond any climatic conditions experienced during the entire current geological period, the Quaternary,” Willeit observes. “A period that started almost 3 million years ago and saw human civilization beginning only 11,000 years ago. So, the modern climate change we see is big, really big; even by standards of Earth history.”