Tipping elements can destabilize each other, leading to climate domino effects

A third of simulations shows domino effects already at up to 2°C global warming

Tipping elements are parts of the Earth system that, once in a critical state, can undergo large and possibly irreversible changes in response to perturbations. They can seem stable until a critical threshold in forcing is exceeded. Once triggered, the actual tipping process may take a long time to unfold. The polar ice sheets for instance would take thousands of years to melt and release most of their ice masses into the oceans, yet with substantial effects: raising sea levels by many meters, threatening coastal cities such as New York, Hamburg, Mumbai or Shanghai. While this is well-known, the dynamics of interacting tipping elements were not.

“Here’s just one example of the many complex interactions between the climate tipping elements: if there is substantial melt from the Greenland Ice Sheet releasing freshwater into the ocean, this can slow down the Atlantic overturning circulation which is driven by temperature and salinity differences and transports large amounts of heat from the tropics to the mid-latitudes and polar regions,” explains Nico Wunderling, first author of the study. “This in turn can lead to net warming in the Southern Ocean, and hence might on the long-run destabilize parts of the Antarctic Ice Sheet. This contributes to sea-level rise, and rising waters at the fringes of the ice sheets in both hemispheres can contribute to further mutually destabilizing them.”

“It would be a daring bet to hope the uncertainties play out in a good way”

Since Earth system models are currently computationally too heavy to simulate how tipping elements’ interactions impact the overall stability of the climate system, the scientists use a novel network approach. “Our conceptual model is lean enough to allow us to run more than three million simulations while varying the critical temperature thresholds, interaction strengths and network structure,” explains Jürgen Kurths, Head of PIK’s Complexity Science Research Department. “By doing so, we could take into account the considerable uncertainties related to these characteristics of tipping interactions.”  

“Our analysis is conservative in the sense that several interactions and tipping elements are not yet considered,” concludes Ricarda Winkelmann. “It would hence be a daring bet to hope that the uncertainties play out in a good way, given what is at stake. From a precautionary perspective rapidly reducing greenhouse gas emissions is indispensable to limit the risks of crossing tipping points in the climate system, and potentially causing domino effects.”