Tipping points in the climate system
In climate science, a tipping point is a critical threshold that, when crossed, leads to large, accelerating and often irreversible changes in the climate system.[3] If tipping points are crossed, they are likely to have severe impacts on human society and may accelerate global warming.[4][5] Tipping behavior is found across the climate system, for example in ice sheets, mountain glaciers, circulation patterns in the ocean, in ecosystems, and the atmosphere.[5] Examples of tipping points include thawing permafrost, which will release methane, a powerful greenhouse gas, or melting ice sheets and glaciers reducing Earth's albedo, which would warm the planet faster.
"Runaway climate change" redirects here. Not to be confused with Runaway greenhouse effect.
Tipping points are often, but not necessarily, abrupt. For example, with average global warming somewhere between 0.8 °C (1.4 °F) and 3 °C (5.4 °F), the Greenland ice sheet passes a tipping point and is doomed, but its melt would take place over millennia.[2][6] Tipping points are possible at today's global warming of just over 1 °C (1.8 °F) above preindustrial times, and highly probable above 2 °C (3.6 °F) of global warming.[5] It is possible that some tipping points are close to being crossed or have already been crossed, like those of the West Antarctic and Greenland ice sheets, the Amazon rainforest and warm-water coral reefs.[7] A danger is that if the tipping point in one system is crossed, this could cause a cascade of other tipping points, leading to severe, potentially catastrophic,[8] impacts.[9]
The geological record shows many abrupt changes that suggest tipping points may have been crossed in pre-historic times.[10]