Il y a 56 millions d’années, l’activité volcanique était responsable de deux événements successifs de réchauffement climatique. Le premier qui ressemble à celui que nous vivons aujourd’hui. Le second, déjà connu sous le nom de maximum thermique du Paléocène-Éocène (PETM), qui pourrait ressembler à ce qui attend notre Terre si nous ne réduisons pas nos émissions de gaz à effet de serre. © Mateusz, Adobe Stock

Global warming like the one we are witnessing has already happened in the past!

56 million years ago, our Earth experienced an exceptionally natural global warming. In question, greenhouse gas emissions are associated with volcanoes. Researchers now assert that this warming was preceded by changes reminiscent of those we are witnessing today. When our planet’s past opens a window into our future…

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In the initial version – which covers only the first nine months of 2021 – of its annual report on the state of the global climate, the World Meteorological Organization (WMO) confirms the trend of global warming. For the first time, the elevation bar has been exceeded by 1°C compared to the pre-industrial averages over the past 20-year period. But above all, the report highlights the many extreme weather events that occurred in 2021 and their consequences for the planet and for humanity. © World Meteorological Organization

56 million years ago, we had a land experienced a global warming phenomena And quickly. Scientists define it as the Paleocene and Eocene Maximum Temperature (PETM). It was caused by a mass release of greenhouse gases. As a result of intense volcanic activity. But an international team of researchers is now showing that this extraordinary warming was preceded by an event that is strangely reminiscent of the climate change we are experiencing today. From emissions From satiate (Ko2) similar to current levels led to a brief warming and acidification of the oceans.

Until then, the sequence of environmental changes that led to PETM remained unclear. But scientists are now hopeful that these two events can provide them with useful information about how our climate could evolve further at the rate of carbon dioxide.2 at’Atmosphere which continues to increase.

Remember that evidence of environmental changes related to PETM is recorded in sediment sailors. calendarabsorb Through the ocean large amounts of carbon dioxide2 from the atmosphere. By analyzing the chemical composition of shells From foraminifera – Microscopic organisms preserved in the form of fossils – thus, researchers can get access, in particular, to the temperature and pH of the oceans at that time. But they lacked excavations that date back to the beginning of the Petam period.

Two main possible scenarios for warming

To overcome this difficulty, researchers dug along the eastern coast of the United States. A region that once corresponded to a Continental shelf prominent. rate sedimentation High for its proximity to the ground and some protection against itocean acidification.

Then they used an innovative technique. One laser Displaying a human hair to sample microscopic plankton and send the vaporized particles to a spectrometer From Collective. This is how they were able to access details they had never seen before. By analyzing only a few available shells, they estimated the acidity, and thus the carbon content, of the oceans at that time. And its results have not been resumed. At the time of the event preceding the PETM period, they observed an increase in carbon emissions on the order of what could be released today through human activities.

This is enough to draw closer parallels with anthropogenic climate change — even if ice peaks Existing climates today increase the sensitivity of the climate to warming. This precursor event is short Duration It looks more like what would happen if the current rate of carbon emissions were reduced rapidly. “This carbon can then dissolve in the depths of the oceans”remarks by James Zakos, Professor of Earth Sciences, at A Statement from the University of California (United State). The previous PETM event shows that it will take hundreds – if not a thousand – years for the climate system to return to pre-industrial equilibrium.

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But this is nothing compared to the hundreds of thousands of years it took for the Earth’s climate to recover from the PETEM period. Extreme warming that indicates what our future could be if we continued to emit carbon dioxide2 at the current rate. And further proof that urgent action is needed to wind our business down greenhouse gases.

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