Afterwarming

Afterwarming refers to a phenomenon where the Earth's climate continues to warm for a period after greenhouse gas concentrations in the atmosphere have stabilized. This is a consequence of the inertia inherent in the climate system, particularly the oceans. Oceans absorb a significant amount of heat from the atmosphere, and this heat is released very slowly. Even if atmospheric greenhouse gas levels were to stop increasing, the stored heat in the oceans would continue to be released, driving further warming for decades or even centuries.

The oceans' vast heat capacity means they act as a buffer against rapid temperature changes, but this also contributes to the persistence of warming trends. Changes in ice sheets and glaciers also contribute to afterwarming, as their melting is a slow process that continues even after warming conditions cease. Furthermore, feedback mechanisms within the climate system, such as the release of methane from thawing permafrost, can continue to operate and amplify warming for a considerable time. Understanding afterwarming is crucial for long-term climate projections and for setting realistic targets for mitigating climate change. It highlights that even immediate cessation of emissions would not result in an immediate halt to global warming.