A sudden global warming occurred 56 million years ago and the causes that led to such a surge have always been a mystery to the scientific community. Now a new study explains that this large temperature rise in the past is related to a change in the Earth’s orbit.
This warming period that occurred 56 million years ago is known as the Paleocene-Eocene Transition Thermal Maximum (PETM). For climatologists, PETM is considered As a phenomenon analogous to contemporary climate change, which has well-known causes (human activity). This climatic episode of the past, which still raises many questions today, was marked by 5 to 8 degrees Celsius of global warming over 10,000 to 20,000 years. This violent climate change caused mass extinctions of species in the oceans as well as on Earth, before a major renewal of species occurred thereafter. This is the largest known global warming on Earth to date, although other past warmings are still under investigation. During this period, large quantities CarbonAn important one Green house gas, published in the atmosphere. But to date, no one really agrees on what causes this carbon release.
Correlation between astronomical movements and terrestrial climate variations
In A study published in Nature CommunicationsScientists from Pennsylvania State University He analyzed sediments from this distant period found on the American coast of Maryland. They used an astrophysical method of dating sedimentary units that made it possible to compare them with the Milankovitch cycles, the different cycles of the Earth. These natural cycles are marked by three major changes:
- The eccentricity of the Earth’s orbit, the distortion of the Earth’s ellipse that can move it closer to or further from the Sun;
- tilt, the tilt of the earth;
- Climate, Earth’s axis of rotation.
There is indeed a correlation between astronomical movements and terrestrial climate variations over the past million years. According to the researchers who published the study, eccentricity and predictability are the main culprits for this sudden warming that occurred 56 million years ago. A change in orbit would certainly cause a large release of carbon, which would cause warming. This change of orbit would have taken place over 6,000 years. Until now, most paleoclimatologists believed that this temperature rise was the main cause Volcanic activity. These variations in Earth’s orbit change the amount of solar radiation it receives and its distribution over different parts of the globe. Then the climate changed, as well as life on Earth.
Human activities have a stronger impact than changes in Earth’s orbit
Scientists at the University of Pennsylvania also confirmed the hypothesis that the rate of release of this carbon was slowed during the PETM by human activities: a finding that the researchers considered “concerned,” meaning Human activities Can have a stronger impact on carbon emissions than changing Earth’s orbit! And the order of magnitude is impressive: the rate at which we emit carbon today is five to ten times that of the PETM. Knowing that the mass extinction followed a climatic event 56 million years ago, Biodiversity decline As we see today, this is a very alarming signal.