A new study published by the journal Science warned Thursday of carbon dioxide levels are saying it has reached “unprecedented in 14 million years.”
The study covers the period from 66 million years ago until today, analyzing biological and geochemical fingerprints from the distant past to reconstruct the historical record of carbon dioxide more accurately than ever before.
“It makes us realize that what we are doing is completely unusual in terms of the history of the Earth,” Purple Hoenisch of the Lamont-Doherty Observatory, affiliated with the Columbia Climatology School, told AFP.
The new study concluded, among other things, that the last time the air contained 420 parts per million of carbon dioxide was 14 to 16 million years ago, when there was no ice in Greenland and human ancestors moved from forests to grasslands.
This is a long time before the period between three and five million years mentioned by previous studies.
Until the late 18th century, carbon dioxide in the atmosphere amounted to about 280 parts per million, which means that humans had already caused a 50 percent increase in greenhouse gases, which trap heat in the atmosphere and led to the planet’s temperature rising by 1.2 degrees Celsius compared to at the pre-industrial revolution level.
If global carbon dioxide emissions continue to increase, we could reach between 600 and 800 parts per million by 2100.
Scientists confirmed that the hottest period over the past 66 million years was 50 million years ago when carbon dioxide reached 1,600 parts per million and the temperature was 12 degrees Celsius higher, before witnessing a decline for a long period.
By 2.5 million years ago, carbon dioxide reached between 270 and 280 parts per million, marking the beginning of the ice ages.
The level remained the same until humans arrived 400,000 years ago and began burning fossil fuels on a large scale.
The team estimates that doubling carbon dioxide could raise the planet’s temperature by between 5 and 8 degrees Celsius, but only over hundreds of thousands of years when temperatures significantly affect Earth’s systems.