Let us not forget about global cooling

A "cold snap" 116 million years ago reportedly triggered a similar marine ecosystem crisis to those witnessed in the past as a result of global warming.

Report: Global cooling ended in the 19th century

The most comprehensive evaluation of temperature change on Earth’s continents over the past 1,000 to 2,000 years indicates that a long-term cooling trend - caused by factors including fluctuations in the amount and distribution of heat from the sun, and increases in volcanic activity - ended late in the 19th century.