Mass extinction with prior warning. Mass extinctions throughout the history of the Earth have been well documented. Scientists believe that they occurred during a short period of time in geological terms. In a new study, paleobiologists have now shown that signs that the largest mass extinction event in the Earth's history was approaching became apparent much earlier than previously believed, and point out that the same indicators can be observed today. Source 4y.
Biggest mass extinction caused by global warming leaving ocean animals gasping for breath. By combining ocean models, animal metabolism and fossil records, researchers show that the Permian mass extinction in the oceans was caused by global warming that left animals unable to breathe. As temperatures rose and the metabolism of marine animals sped up, the warmer waters could not hold enough oxygen for their survival. Source 3z.