Current climate policies present a significant risk of triggering tipping points in critical Earth system elements, even if temperatures temporarily exceed and then return below 1.5°C of global warming. A new study reveals that these risks can be significantly minimized if warming is swiftly reversed.
Anthropogenic climate change threatens the stability of large-scale components of the Earth system, such as ice sheets, ocean currents, and global ecosystems—known as tipping elements. Researchers from IIASA and the Potsdam Institute for Climate Impact Research (PIK) have analyzed the risks to four interconnected core climate tipping elements under current mitigation efforts and future emission scenarios. Their findings are detailed and published in Nature Communications.
The study highlights the dangers of destabilizing key climate elements due to exceeding the 1.5°C threshold. These elements include the Greenland Ice Sheet, the West Antarctic Ice Sheet, the Atlantic Meridional Overturning Circulation (a major Atlantic Ocean current), and the Amazon Rainforest. Each plays a crucial role in maintaining Earth’s climate stability, and global climate change could trigger abrupt and irreversible changes in these systems.
The study indicates that current policies could commit us to a high tipping risk of 45% by 2300, even if temperatures are brought back below 1.5°C after a period of overshoot. Tipping risks remain substantial across several future emission scenarios. If we fail to reduce warming to below 1.5°C by 2100, we face tipping risks of up to 24% by 2300.
Every fraction of a degree above 1.5°C increases tipping risks. Surpassing 2°C of global warming would significantly escalate these risks. On that note, scenarios following current climate policies is extremely concerning as it could lead to about 2.6°C of warming by the end of this century.
Only a swift reversal of warming after any overshoot can effectively limit tipping risks, necessitating at least net-zero global greenhouse gas emissions, as outlined in Article 4 of the Paris Agreement.
“This analysis of tipping point risks adds further support to the conclusion that we are underestimating risks, and need to now recognize that the legally binding objective in the Paris Agreement of holding global warming to well below 2°C, in reality means limiting global warming to 1.5°C. Due to insufficient emission reductions, we run an ever increasing risk of a period of overshooting this temperature limit, which we need to minimize at all costs to reduce dire impacts to people across the world,” concluded study author, Johan Rockström.
