CO2 greenhouse gas amounts in the atmosphere are likely higher today than ever before in the past 3 million years.
CO2 greenhouse gas amounts in the atmosphere are likely higher today than ever before in the past 3 million years. For the first time, a team of scientists succeeded to do a computer simulation that fits ocean floor sediment data of climate evolution over this period of time. Ice age onset, hence the start of the glacial cycles from cold to warm and back, the study reveals, was mainly triggered by a decrease of CO2-levels. Yet today, it is the increase of greenhouse gases due to the burning of fossil fuels that is fundamentally changing our planet, the analysis further confirms. Global mean temperatures never exceeded the preindustrial levels by more than 2 degrees Celsius in the past 3 million years, the study shows – while current climate policy inaction, if continued, would exceed the 2 degrees limit already in the next 50 years.
“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 of the Potsdam Institute for Climate Impact Research, lead author of the study now published in Science Advances. “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. 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.”
Read more at Potsdam Institute for Climate Impact Research (PIK)
