CO2 levels at the highest since 3 million years – when the sea was 20 meters higher

(CNN) – The last time carbon dioxide levels were so high, Greenland was mostly green, sea level was up to 20 meters higher and trees were growing in Antarctica, according to scientists who warned this week that there is more CO2 in our atmosphere today than in the last three years. millions of years.

Using a new computer simulation, researchers at the Institute for Climate Impact Research (PIK) in Potsdam, Germany, discovered that the last time the Earth's atmosphere had a CO2 concentration also higher than that of today, was during the Pliocene period, the geological period 2.6-5.3 million years.

CO2 emissions from human activities are the main cause of climate change.

The amount of CO2 in the atmosphere today is "unnatural," CNN Senior Matteo Willeit told CNN.

Willeit said that, according to the simulation, CO2 levels should not exceed 280 parts per million (ppm) without human activity, but that they are currently 410 ppm and increasing.

Global average temperatures have risen much faster than ever since the Pliocene, Willeit added.

During this period, they have never exceeded pre-industrial levels by more than 2 ° C, but current models show that temperatures will increase by 4 ° C between 2000 and 2100 if no action is taken for reduce emissions, he said.

In unknown territory

Willeit said rising CO2 levels push the Earth beyond the climatic conditions never before seen by humans.

If CO2 levels and temperatures continue to rise, "our planet will change" and the sea level will rise by one or two meters in the next 200 years, he added.

This research is not the first to suggest that current CO2 levels are the highest since the Pliocene, but Potsdam researchers claim that their work is the first to combine ocean bottom sediment data with Analysis of past ice volumes, and are more sophisticated than others. model studies.

At a meeting of the Pliocene Royal Meteorological Climate Society in London on Wednesday, scientists explained how the sedimentary records and plant fossils of the Antarctic show that during the Pliocene period, summer temperatures Arctic were 14 ° C higher than today.

Professor Martin Siegert, of Imperial College London, said during the event that his findings offered a vision of the future of the Earth if no drastic action was taken to fight against global warming.

This story was first published on CNN.com "The highest CO2 levels recorded for 3 million years, while the sea was 20 meters higher"