While global warming is considered to be the direct result of man-made activities, new research has claimed that the responsibility for climate change phenomenon also lies with Earth’s first animals that evolved more than 500 million years ago. The results of the research were published in the journal, Nature Communications, it was reported in July 2018.
Around 500 million years ago, these first animals evolved in the ocean and began to burrow into the sea floor, leaving fossilized burrows that are now the only evidence of their existence. The disturbance of the underwater sediments led to the breakdown of the organic matter and brought about major environmental shifts. In the 100 million years that followed, conditions for these earliest animals became much harsher, as ocean oxygen levels fell and CO2 caused global warming.
The evolution of these small animals also increased atmospheric carbon dioxide levels to such an extent that it caused a global warming event. Scientists were aware of this warming that occurred at this point in the history of the Earth but did not realize that it could be driven by animals.