The Great Dying wiped out at least 90% of the species on Earth due to an abrupt rise in global-average temperature about 252 million years ago. The vast majority of complex life became extinct. Based on information from the most conservative sources available, Earth is headed for a similar or higher global-average temperature in the very near future. The recent and near-future rises in temperature are occurring and will occur at least an order of magnitude faster than the worst of all prior Mass Extinctions.