To have a 50% chance of reaching 1.5°C and thus limiting tipping point risks, global greenhouse gas emissions must be halved by 2030, reaching net-zero emissions by 2050.
Co-author Johan Rockström, co-chair of the Earth Council and director of the Potsdam Institute for Climate Impact Research, said: “The world is moving towards a global warming of 2-3°C.
“This puts the planet on a path to cross multiple dangerous tipping points, which are catastrophic for people all over the world.
“To maintain habitable conditions on Earth, protect people from extreme events, and achieve stable societies, we must do everything possible to prevent tipping points from being crossed. Every tenth of a degree counts.”
Tim Renton, Director Global Systems Institute Member of the University of Exeter and Earth Council, and a co-author of the report. “Since I first assessed climate tipping points in 2008, the list has grown and our assessment of the risks they pose has grown dramatically,” he said.
“Our new work provides compelling evidence that the world must radically accelerate economic decarbonization to limit the risk of crossing a climate tipping point.
“To achieve this, we now need to trigger positive societal tipping points to accelerate the transition to a clean energy future.
“We may also have to adapt to deal with climate tipping points that we cannot avoid and support those who may suffer uninsurable losses and damage.”
By searching through paleoclimate data, current observations and the output of climate models, the international team concluded that 16 major biophysical systems (so-called “tipping factors”) involved in regulating Earth’s climate have the potential to cross a tipping point that would allow Change is self-sustaining.
This means that even if temperatures stop rising, once an ice sheet, ocean or rainforest has passed a tipping point, it will continue to change to a new state.
How long the transition takes can vary from decades to thousands of years, depending on the system.
For example, ecosystems and atmospheric circulation patterns can change rapidly, while ice sheets collapse more slowly, but cause inevitable sea-level rises of several meters.
The researchers grouped the dumping factors into nine systems that affect the entire Earth system, such as Antarctica and the Amazon rainforest, and another seven that would have far-reaching regional effects if dumped.
The latter includes the West African monsoon and the death of most coral reefs around the equator.
Several new overturning elements were added compared to the 2008 assessment, such as Labrador Sea convection and the East Antarctic subglacial basin, while Arctic summer sea ice and the El Niño Southern Oscillation due to lack of evidence of overturning dynamics (ENSO) has been removed.
“Importantly, many tipping points in the Earth system are interconnected, making cascading tipping points a serious additional problem,” said co-author Ricarda Winkelmann, a research fellow at the Potsdam Institute for Climate Impact Research and member of the Earth Council.
“In fact, interactions can lower the critical temperature threshold beyond which individual detonating elements become unstable in the long run.”
Yasmin Dahnoun is ecologist. This article is based on a press release from the University of Exeter.