MIAMI. A group of scientists found direct evidence that a comet hit the Earth some 55 million years ago, which would have led to a period of substantial warming of the temperatures.
The findings, published Thursday in the american magazine Science, support the theory that an unexpected impact -and not a volcanic eruption – could lead to a stage of warming known as the Thermal Maximum of the Paleocene-Eocene (PETM, in English).
"This could be the reason. (The Earth) warmed up very quickly. This suggests where it came from," explains study co-author, Dennis Kent, researcher of the Observatory Lamont-Doherty of Columbia University, and Rutgers University.
Kent and other scientists found small droplets round glass calls microtectitas digging in what is now New Jersey in the eastern united States. It is believed that these spheres the size of a grain of sand is formed when an object of extraterrestrial impacts against the Earth, spreading vaporized material that solidifies when it is in the air, according to the study.
"it Has to be more than a coincidence that there were a impact at that time," says the lead author, Morgan Schaller, geochemical, Rensselaer Polytechnic Institute. "If the impact is related to the (warming), this suggests that the carbon release was fast," explains the expert.
The scientists claim that the emanation of carbon occurred during a period of between 5,000 and 20,000 years. Other theories suggest that a period of volcanic caused a warming of the planet, causing the release of substances such as methane frozen on the seabed.
Some researchers believe that the changes suffered by the earth’s orbit or the modification of marine currents also played an important role in the increase of the temperature of between 5 and 9°C for about 200,000 years.
The changes assumed that the ice had nearly disappeared from the Earth, and the sea level rose to levels much higher than today. Also, some species disappeared and others migrated towards the poles.
The experts say that carbon emissions "are currently much more important than what happened during the PETM", according to a press release from the University of Columbia. "The consequences can be more drastic, because many types of life do not have time to evolve."
Another study published at the beginning of 2016 showed that the emissions of carbon dioxide, the main greenhouse gas, releasing 10 times more carbon in the atmosphere due to the fossil fuels that the natural forces that caused the warming 55 million years ago. With regard to the theory of the comet, scientists have not found any crater that has been caused by massive impact.
"Can that happen near or happen on the other side of the planet," says Schaller. As the small spheres spread very little, the impact could be larger, but further away, or up close, but relatively. In accordance with Charles Langmuir, a paleoclimatólogo of Harvard University who was not involved in the study, the evidence of an impact during or near the start of the PETM "is very strong".
Langmuir also stresses that the study does not explain who caused the release of carbon or how long it lasted, and also ensures that the small spheres are derived from an enormous impact that occurred 55 million years ago.
The researchers established the age of the areas using radiometric dating, leaving the door open to come from another period, according to Christian Koeberl, an expert from the University of Vienna.
it Is believed that an object of extraterrestrial impact in the Yucatan peninsula (Mexico) to 11 million years before led to the disappearance of the dinosaurs.
About 20 million years after the period PETM registered another impact on the area, creating the that is now known as the Chesapeake bay, off the coast of the state of Maryland.
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