The planet has endured the effects of global warming which we see today about 56 million years ago. The present stage of global warming has been caused by unbridled human activities whereas the global warming of the past was triggered by a catastrophic collision with a comet or asteroid with the earth.
American researchers have published the first physical evidence of a comet’s impact on the planet millions of years ago in the Journal Science.
The researchers were looking at the fossilised remains of a tiny organism called Foraminifera when they accidently stumbled upon a microtektite in the sediment. It belonged to a period in the past age when there was an incidence of global warming. The microtektite is a glassy bead-like structure which is formed by extraterrestrial impacts.
It is a remarkable coincidence of a major impact on a major climate change, and this is remarkable. Researchers look for fossilised remains in sediments which belonged to an era when global warming took place or the Paleocene-Eocene Thermal Maximum (PETM). The microtektite is black in colour and therefore difficult to spot on the dark coloured sorting tray which scientists were using.
The microtektite is a positive evidence of a catastrophic impact on the planet of a comet or an asteroid. There is evidence of tiny craters or material sintered together, which is proof of the speed they were travelling at.
The period also saw a rapid increase in carbon dioxide levels resulting in a steep rise in temperatures on the order of 5 to 8 degrees and the increase lasted for more than 15,000 years. However, researchers have not been able o figure out how this period ended.
Fossils recovered at this time showed a sudden rise in the ratio of carbon isotopes. The organism Foraminifera produces a shell whose composition closely resembles the ratio of Carbon isotopes in the atmosphere and ocean. This ratio of carbon isotopes in a particular species remains stable for a major portion of an era and then suddenly fluctuates wildly and then wiggles back and forth before stabilising over the course of thousands of years.
The evidence hinted of a catastrophic event when the composition of the atmosphere changed adding carbon from a source depleted in carbon-13. Most probably a comet or asteroid may have contributed carbon to the atmosphere and acted as a trigger for additional carbon release from other sources.