A team of American researchers has found evidence that a large warming that began on Earth about 56 million years ago may be linked with a comet that smashed into the planet around that time. Published Friday in the journal Science, the study suggests that the cosmic crash may have resulted in carbon being released into the atmosphere and triggering a feedback loop that significantly contributed to increased temperatures.
The extinction of dozens of species occurred after the Earth warmed by about 9 to 14 degrees and then returned to normal within 100,000 years. These higher world temperatures and increased ocean levels also contributed to the rise of mammals and other animals that spread across the globe, as reported by BBC.
Because comets typically carry a carbon isotope scientifically known as Carbon-12, the researchers believe that an extraterrestrial impact may have led to the ancient climate change. Scientists have known for years that this isotope became abundant in the era of the massive warming and this time period is called Paleocene-Eocene Thermal Maximum (PETM).
The theory is contained in ancient, glassy teardrops and spheres
Morgan Schaller, an assistant professor of earth and environmental sciences at the Rensselaer Polytechnic Institute, was part of the team of researchers who were looking at sediment cores found in New Jersey and one and off Florida from 56 million years ago.
They saw tiny glass and crystal objects about .004 inches long (100 microns). Some of them looked like spheres and others like teardrops, but all of them appeared to have the unique chemical mark of quartz, which was undoubtedly shocked by a super-hot phenomenon.
The researchers carefully studied the sediment cores and found microtektites. These are tiny spherical pieces that usually emerge as a consequence of asteroid impacts and melt before vaporizing the ground. The microtektites then throw molten ejecta into the air and fall after solidifying. The existence of shocked quartz in these little pieces is evidence of intense pressure.
“This tells us that there was an extraterrestrial impact at the time this sediment was deposited – a space rock hit the planet,” Schaller said in a press release, as reported by the Christian Science Monitor.
He described the coincidence of an impact of these characteristics on a large warming as “remarkable.” Schaller was careful not to affirm that one thing caused the other but pointed out that further research is needed to understand the link between these extraordinary events better. His team wants to know more about this coincidence to get more clues about the global warming our planet is facing today.
Critics
Mark Boslough, a physicist at Sandia National Lab whose research is about asteroid collisions and climate change, said every scientist know that carbon dioxide combined with methane act as “heat-trapping blankets,” as reported by CBS News. Boslough was not part of the study, but his comment suggests he believes the theory published in Science seems plausible.
For his part, Bruce Simonson at Oberlin University described the study as “new and exciting,” mainly because Schaller’s team are talking about sediments from a comet impact that had not been discussed before, CBS reported.
However, several others are not convinced whatsoever, including James Zachos of University of California, Santa Cruz. He believes that there is now way carbon could have been released into the air as rapidly as needed to cause the massive warming. He noted that a crash could not have been able to release “even a small fraction” of the huge amount of carbon required to contribute to climate change, according to the CBS report.
Other scientists explain the climate shift as an event that took place as a great number of volcanoes erupted. Andy Ridgell at the University of California, Riverside and the University of Bristol in England, is one of the experts who thinks this is a more plausible explanation, according to CBS. For example, some volcanoes in Greenland heated up a coal field, which triggered a lot of carbon dioxide into the atmosphere.
Source: CBS News