If we knew that life on Earth would disappear in several billion years due to the aging of the Sun, it could be much sooner for mammals. According to one study published Monday in the magazine Nature Geosciencethe formation of an ultimate Pangea, a supercontinent resulting from the rapprochement of the continents within 250 million years, will cause such a rise in temperatures that almost no area of the Earth will be habitable by mammals.
The movement of tectonic plates linked to the emergence of this supercontinent would indeed cause strong volcanic activity. “The formation of the continent will create oceanic ripples, which will generate degassing and the release of CO2 in the rocks deep within the Earth,” explains Anta-Clarisse Sarr, paleoclimatologist at the Grenoble Institute of Earth Sciences. This CO2 will rise and be released into the ocean, then into the atmosphere.” This phenomenon is added to the magmatic activity linked to the thinning of the earth’s surface and the overlapping of certain plates. All this would worsen the greenhouse effect, thus causing considerable warming of our planet that mammals will not be able to withstand.
92% of Earth uninhabitable
According to the study, temperatures oscillate between 40 and around fifty degrees Celsius, a climate too hostile for humans and their fellow humans. The regions located in the middle of the continent, transformed into deserts, will be uninhabitable, “except for very specific mammals”, according to Alexander Farnsworth, researcher at the University of Bristol and co-author of the study. The scientist anticipates “a mass extinction”, and “not only for mammals. This could also concern plants and other types of life.” However, some species may survive and adapt, but the study authors say it is impossible to predict.
In the worst case, that is to say that of a concentration of CO2 in the air twice as high as in our time, only 8% of the Earth would still be habitable, compared to 66% currently, d ‘after the researchers.
The overall increase in temperatures will also be due to the activity of the Sun, which will emit, according to scientists, around 2.5% more energy than today, therefore releasing more heat. Conversely, if the authors of the study believe that the ultimate Pangea should form at the equator, it is also possible that the supercontinent will ultimately be located further north. “The amount of solar radiation, and therefore heat, is higher at the equator because the Earth is round,” explains Anta-Clarisse Sarr. At the poles, it is therefore cooler”, which would allow conditions more conducive to life.
A study to qualify
The Earth’s climate is effectively determined, excluding human intervention, by “its geography, that is to say the distribution of continents and oceans, their height, their depth, and by the concentration of CO2, which is the result of the balance between the CO2 emitted by volcanic activity and that absorbed naturally by the rocks,” describes Anta-Clarisse Sarr.
But for certain scientists, including Yves Godderis, research director at the CNRS assigned to the Environmental Geosciences laboratory in Toulouse, this study should be taken with great caution. “Determining the position of the continents in 250 million years is not simple,” he adds. Researchers have extended current trends, but the future reality is very unclear. » The same goes for the notion of mammals: “We can extrapolate, but evolution is very complex, we do not know what there will be 250 million years from now, it is a point of very anthropocentric view. We don’t know anything about it, especially on this time scale. »
But this study is still of interest to Anta-Clarisse Sarr: “It shows in particular that life on Earth is very fragile.” It can also be beneficial for future research because “the researchers managed to combine many tools that are usually used independently,” according to the paleoclimatologist. This specifies that this “methodological construction is interesting because it is applicable to other objects of study”, such as research on past life or the evolution of other planets.