An abrupt climate change occurs when the climate system is forced to transition to a new state at a rate that is determined by the climate system itself, and which is more rapid than the rate of change of the external forcing. Past events include the end of the Carboniferous Rainforest Collapse

Carboniferous Rainforest Collapse

The Carboniferous Rainforest Collapse was an extinction event that occurred around 305 million years ago in the Carboniferous period). Vast coal forests covered the equatorial region of Euramerica...

, Younger Dryas

Younger Dryas

The Younger Dryas stadial, also referred to as the Big Freeze, was a geologically brief period of cold climatic conditions and drought between approximately 12.8 and 11.5 ka BP, or 12,800 and 11,500 years before present...

, Dansgaard-Oeschger event

Dansgaard-Oeschger event

Dansgaard–Oeschger events are rapid climate fluctuations that occurred 25 times during the last glacial period. Some scientists claim that the events occur quasi-periodically with a recurrence time being a multiple of 1,470 years, but this is debated...

s, and possibly also the Paleocene-Eocene thermal maximum

Paleocene-Eocene Thermal Maximum

The most extreme change in Earth surface conditions during the Cenozoic Era began at the temporal boundary between the Paleocene and Eocene epochs . This event, the Paleocene–Eocene Thermal Maximum , was associated with rapid global...

. The term is also used within the context of global warming

Global warming

Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...

 to describe sudden climate change that is detectable over the time-scale of a human lifetime.