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Tipping points

This article describes the concept of climate tipping points, and introduces the possibility that permafrost thaw may have a tipping point.
A lone researcher walks along the ridge of the snowy Chugach mountains in Alaska.
© Woodwell Climate Research Center

The United Nations Intergovernmental Panel on Climate Change has published numerous reports warning that passing 1.5 degrees Celsius of average global warming will have catastrophic repercussions for the planet—a threshold that we are inching closer and closer towards.[1]

Surpassing that limit also risks pushing us beyond numerous climate tipping points.

Climate tipping points are often compared to knocking out the keystone piece of a balancing tower: they are critical natural limits that, if surpassed, could cause large and irreversible damage to the climate system beyond the point of no return.[2] Examples of phenomena that some scientists consider to be climate tipping points include permafrost loss, Greenland ice sheet disintegration, circulation breakdown in the Atlantic, the northward shift of boreal forests, destruction of the Amazon rainforest, West Antarctic ice sheet disintegration, and coral reef die-off.[3]

The sink or source strength of an area using the annual average ecosystem carbon dioxide exchange for 1990-2015. Map by: Greg Fiske

Permafrost is extremely vulnerable to climate change and as temperatures rise, aggravating permafrost’s positive feedback loop, the ecosystem could potentially flip from a carbon sink—one that sequesters more carbon than it emits; to a carbon source—one that emits more carbon than it sequesters, further accelerating the climate crisis. This transition from carbon source to sink is what some scientists are concerned would be the tipping point of the permafrost ecosystem.


1WMO. 2022. WMO update: 50:50 chance of global temperature temporarily reaching 1.5°C threshold in next five years. [online] Available at: [Accessed 30 August 2022].

2Cho, R., 2021. How Close Are We to Climate Tipping Points?. [online] State of the Planet. Available at: [Accessed 30 August 2022].

3McSweeney, R., 2022. Explainer: Nine ‘tipping points’ that could be triggered by climate change. [online] Carbon Brief. Available at: [Accessed 30 August 2022].

© Woodwell Climate Research Center
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Thawing Permafrost: Science, Policy, and Environmental Justice in the Arctic

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