CO2 levels at highest for 3 million years -- when seas were 20 meters higher

The last time CO2 levels were as high as today, 3 million years ago, Greenland (pictured) was mostly green and sea levels were 20 meters higher. Photo taken on March 30, 2017.

Story highlights

  • Rising CO2 levels are pushing earth beyond any climatic conditions ever experienced by humans, scientists warn.
  • Global mean temperatures are rising much faster than any time since the Pliocene, when sea levels were up to 20 meters higher.
  • CO2 levels are currently 410 parts per million.

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

Using a new computer simulation, researchers at the Potsdam Institute for Climate Impact Research (PIK), in Germany, found that the last time the earth's atmosphere had a CO2 concentration as high as today's was during the Pliocene epoch, the geological period 2.6-5.3 million years ago.
    CO2 emissions from human activities are the leading cause of climate change.