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

56 million years ago, our Earth experienced quite exceptional natural global warming. In question, greenhouse gas emissions linked to volcanism. And researchers are now confirming that this warming was preceded by changes that are reminiscent of those we are experiencing today. When the past of our Planet opens a window on our future…

56 million years ago, our Earth experienced a significant global warming and fast. Scientists identify it as the Paleocene-Eocene Thermal Maximum (PETM). It was caused for a mass release of greenhouse gas. The result of intense volcanic activity. But an international team of researchers is now showing that this exceptional warming was preceded by an event that is strangely reminiscent of the climate change we are experiencing today. From emissions of carbon dioxide (CO₂) similar to current levels led to brief warming and acidification of the oceans.

Until then, the sequence of environmental changes that led to PETM remained unclear. But scientists now hope that these two events can provide them with useful information about how our weather could evolve further with a CO level₂ in the atmosphere which continues to increase.

Recall that evidence of environmental changes related to the PETM is recorded in the sediment sailors. The result of theabsorption by the ocean large amounts of CO₂ of the atmosphere. By analyzing the chemical composition of shells of foraminifera — microscopic organisms preserved in the form of fossils — researchers thus have access, in particular, to the temperature and pH of the oceans of the time. But they lacked fossils dating back to the beginning of the PETM.

Two major possible warming scenarios

To overcome this difficulty, the researchers drilled along the eastern seaboard of the United States. A region that once corresponded to a shallow continental shelf. With a rate of sedimentation high due to its proximity to the earth and some protection againstocean acidification.

They then used an innovative technique. One laser the width of a human hair to sample the plankton microscopic and send the vaporized particles to a spectrometer of mass. This is how they were able to access details never seen before. By analyzing only a few available shells, they estimated the acidity, and therefore the carbon content, of the oceans at the time. And their results are without appeal. At the time of the event that preceded the PETM, they observe an increase in carbon emissions on the order of what can be released today by human activities.

This is enough to draw closer parallels with the anthropogenic climate change — even if the ice caps that exist today increase the climate’s sensitivity to warming. This precursor event of short duration seems more similar to what could happen if the current rate of carbon emissions were to be rapidly reduced. “This carbon could then dissolve in the depths of the oceans”remarks James Zachos, professor of Earth sciences, in a statement from the University of California (United States). The precursor event of the PETM shows that it would take hundreds — if not a thousand — of years for the climate system to return to its pre-industrial equilibrium.

But that’s nothing compared to the hundreds of thousands of years it took for Earth’s climate to recover from the PETM. Extreme warming that suggests what our future could be if we continue to emit CO₂ at the current rate. And further proof that urgent action is needed to end our greenhouse gas.