Here’s a good scare to wake you up this morning. CBC is reporting that according to a new study of fossil records, whenever the world’s tropical seas warm several degrees, Earth has experienced mass extinctions over millions of years.

Four of the five major extinctions over 520 million years of Earth history have been linked to warmer tropical seas, something that indicates a warmer world overall, said the study… Earth is on track to hit that same level of extinction-connected warming in about 100 years unless greenhouse gas emissions are curbed, top scientists say… And scientists fear it may be about to happen again — but in a matter of several decades, not tens of millions of years.