Destabilising interactions in the climate system: How tipping elements interact

Beyond 2°C of global warming, the risk of one climate tipping element triggering other tipping elements in the Earth’s climate system strongly increases. Furthermore, most of these interactions are destabilising. This is the result of a new study by an international team of scientists, led by Anna von der Heydt from Utrecht University and Nico Wunderling from the Potsdam Institute for Climate Impact Research. The study was published on 26 January in the scientific journal Earth System Dynamics, and sets out the scientific background to chapter 1.5 of the recently published Global Tipping Points Report.

Tipping elements are parts of the climate system that, when changes exceed a threshold, can undergo abrupt and irreversible transformations. The threshold is called the tipping point. And while recent research has deepened the knowledge on individual tipping elements, like polar ice sheets, tropical rainforests or permafrost regions, the interactions between them are less well understood. However, most tipping elements are linked to other tipping elements via circulation systems in the ocean and atmosphere. This means that the tipping of one element may trigger the tipping of another element, like a domino effect.

Tipping cascade

The new study provides an overview of the current knowledge of tipping element interactions and the potential for a domino effect, or tipping cascades. The authors gathered evidence from model simulations, observations, and conceptual understanding, as well as examples of paleoclimate reconstructions. “Although many interactions have not been investigated in much detail yet, we found that there are many potential links between different tipping elements”, Von der Heydt says.

Our assessment suggests that nine interactions between tipping points are of destabilising nature

Beyond 2°C

“More importantly, our assessment suggests that nine interactions between tipping points are of destabilising nature, two are stabilising and three are unclear in their nature”, Von der Heydt explains. Should global warming continue, the destabilising interactions can lead to a cascade of abrupt changes. If global warming surpasses 2°C, tipping cascades may include tipping elements, such as the Atlantic Meridional Overturning Circulation or the Amazon rainforest.

Lower tresholds

Between 1.5 to 2°C, the risk of tipping cascades is less likely but also possible. “However”, Von der Heydt adds, “it's important to note that the Greenland and Antarctic ice sheets are tipping elements that have thresholds at relatively low global warming levels and also have the potential of initiating a cascade.” In order to improve risk assessments, more emphasis in tipping points research has to be put on potential interactions, the researchers conclude.