A doubling of the amount of CO2 in the atmosphere could cause an increase in the average temperature on Earth from 7 to a maximum of 14 degrees. This is shown in the analysis of sediments from the Pacific Ocean off the coast of California, by researchers at NIOZ and the Universities of Utrecht and Bristol. Their results were published in Nature Communications

"The temperature rise we found is much larger than the 2.3 to 4.5 degrees that the UN climate panel, IPCC, has been estimating so far," said the first author, Caitlyn Witkowski.

The researchers used a 45-year-old drill core extracted from the bottom of the Pacific Ocean. "I realized that this core is very attractive for researchers, because the ocean floor at that spot has had oxygen-free conditions for many millions of years," said Professor Jaap Sinninghe Damsté, senior scientist at NIOZ and professor of organic geochemistry at Utrecht University.