Risk of multiple climate tipping points have escalated

Stockholm - Multiple climate tipping points could be triggered if global temperature rises beyond 1.5°C above pre-industrial levels, according to a major new research analysis published in the journal Science.

Even at current levels of global heating the world is already at risk of passing five dangerous climate tipping points, and risks increase with each tenth of a degree of further warming.

An international research team synthesised evidence for tipping points, their temperature thresholds, timescales, and impacts from a comprehensive review of over 200 papers published since 2008, when climate tipping points were first rigorously defined.

They have increased the list of potential tipping points from nine to sixteen.

The research found human emissions have already pushed Earth into the tipping points danger zone.

Five of the sixteen may be triggered at today's temperatures: the Greenland and West Antarctic ice sheets, widespread abrupt permafrost thaw, collapse of convection in the Labrador Sea, and massive die-off of tropical coral reefs.

Four of these move from possible events to likely at 1.5°C global warming, with five more becoming possible around this level of heating.

Researchers from the Stockholm Resilience Centre, University of Exeter, and the Earth Commission say they can see signs of destabilisation already in parts of the west Antarctic and Greenland ice sheets, in permafrost regions, the Amazon rainforest, and potentially the Atlantic overturning circulation as well.

The world is already at risk of some tipping points. As global temperatures rise further, more tipping points become possible. The chance of crossing tipping points can be reduced by rapidly cutting greenhouse gas emissions, starting immediately.

The sixth assessment report of the Intergovernmental Panel on Climate Change (IPCC) says risks of triggering climate tipping points become high by around 2Cdeg above pre-industrial temperatures and very high by 2.5 to 4Cdeg.

The new analysis indicates that Earth may have already left a safe climate state when temperatures exceeded approximately 1Cdeg warming.

A conclusion of the research is therefore that even the United Nations' Paris Agreement goal to limit warming to well-below 2Cdeg and preferably 1.5Cdeg is not enough to fully avoid dangerous climate change.

According to the assessment, tipping point likelihood increases markedly in the Paris range of 1.5 to 2Cdeg warming, with even higher risks beyond 2Cdeg.

There is an urgent need for a deeper international analysis, especially on tipping element interactions, towards which the Earth Commission is starting a tipping points model intercomparison project.