A massive study has revealed that current levels of carbon dioxide in the atmosphere have not been reached in 14 million years on Earth, and points to the inhospitable climates humanity is headed towards.
This publication is in the magazine SciencesH (A new window) (in English) Tracks carbon dioxide levels from 66 million years BC to today’s global warming with unprecedented precision.
This shows us how strange what we are really doing in Earth’s history is.
Lead author Berbil Hüneş, a researcher at Columbia University in New York, explains to AFP.
The last time our planet’s atmosphere contained the same concentration of the major greenhouse gas (CO2) as it does today, about 420 parts per million (ppm), was about 14 to 16 million years ago.
This dates back much longer than scientists previously estimated (3 to 5 million years ago).
For example, 14 to 16 million years ago, there was no ice cover on Greenland.
gold, Our civilization has become accustomed to the sea levels we currently live in, to hot tropical regions, cold Arctic regions, and temperate regions that benefit from abundant rainfall.
Purple Honish warns.
Our species […] It has evolved for only 3 million years. We have never experienced anything like these hot climates before.
Before the industrial era, the concentration of carbon dioxide in the atmosphere was about 280 parts per million. This has increased by half with human activities, causing temperatures to rise by about 1.2 degrees Celsius.
If our emissions continue, the concentration could rise to 600 or 800 ppm, rates that were reached during the Eocene (30 to 40 million years ago), before Antarctica was covered by ice and when the planet’s wildlife and plants were very different, on the Example: large insects.
The study was published on Thursday in science It is the result of seven years of work by a group of 80 researchers in 16 countries. Their conclusions are now considered a scientific consensus.
Their contribution lies not in collecting new data, but in the painstaking work of re-evaluating and compiling existing work to update it and classify it according to its reliability, which made it possible to use the best data in order to draw a comprehensive picture.
To reconstruct past climates, one well-known technique is to recover air bubbles from deep within the ice caps that trapped the composition of the atmosphere at the time. But this technology only allows us to go back a few hundred thousand years.
To move forward, you have to use indirect signs. The chemical study of ancient minerals, leaves or plankton has made it possible to deduce the concentration of carbon dioxide at certain older periods.
Over the past 66 million years, the warmest period Earth has ever known was about 50 million years ago, with carbon dioxide concentrations at 1,600 ppm and temperatures 12°C warmer than today.
The latter declined slowly until 2.5 million years ago and in the time of ice ages, the concentration of carbon dioxide fell to 270-280 ppm.
These levels remained stable until humanity burned fossil fuels on a large scale.
Disastrous consequences
According to the study, doubling the rate of carbon dioxide concentration would lead to a gradual rise in the temperature of the planet, over hundreds of thousands of years, until it reaches +5 to 8 degrees Celsius, due to the cascading effects that may be caused by increasing temperatures.
Thus, melting polar ice reduces its ability to reflect sunlight, which increases the speed of melting, etc.
The study shows that 56 million years ago, Earth’s atmosphere experienced a rapid increase in carbon dioxide concentration similar to that seen today that caused massive changes in ecosystems and took about 150,000 years to dissipate.
We are here for a very long time, unless we can capture carbon dioxide from the atmosphere and stop our emissions very soon
Purple Honish sums up.
“Hardcore beer fanatic. Falls down a lot. Professional coffee fan. Music ninja.”
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