Tag: Tipping Points

Temporarily passing Paris climate targets could ‘significantly’ raise tipping point risk: Study

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Hurricane Ian approaches the west coast of Florida, NASA Johnson (CC BY-NC-ND 2.0)

“To effectively prevent all tipping risks, the global mean temperature increase would need to be limited to no more than 1°C—we are currently already at about 1.2°C,” noted one scientist.

By Jessica Corbett, Common Dreams

Surpassing the global temperature targets of the Paris climate agreement, even temporarily, could dramatically increase the risk of the world experiencing dangerous “tipping points,” according to research published Friday.

The Intergovernmental Panel on Climate Change (IPCC) defines tipping points as “critical thresholds in a system that, when exceeded, can lead to a significant change in the state of the system, often with an understanding that the change is irreversible.”

Published in the journal Nature Climate Change, the new study focuses on the potential shutdown of the Atlantic Meridional Overturning Circulation (AMOC), the Amazon rainforest shifting to savannah, and the collapse of the Greenland and West Antarctic ice sheets.

Under the 2015 Paris deal, governments agreed to work toward keeping global temperature rise this century below 2°C, ultimately aiming for limiting it to 1.5°C. However, scientists continue to warn the countries’ pledges and actions to cut planet-heating emissions are far from bold enough to reach those goals, and critics blasted the COP27 summit in Egypt last month as “another terrible failure” given that the conference’s final agreement did not call for rapidly phasing out all fossil fuels.

“To effectively prevent all tipping risks, the global mean temperature increase would need to be limited to no more than 1°C—we are currently already at about 1.2°C,” noted study co-author Jonathan Donges, co-lead of the FutureLab on Earth Resilience in the Anthropocene at the Potsdam Institute for Climate Impact Research (PIK). “The latest IPCC report is showing that we’re most likely on a path to temporarily overshoot the 1.5°C temperature threshold.”

The researchers examined various scenarios with peak temperatures from 2°C to 4°C. As lead author and PIK scientist Nico Wunderling explained, they found that “the risk for some tipping events could increase very substantially under certain global warming overshoot scenarios.”

“Even if we would manage to limit global warming to 1.5°C after an overshoot of more than 2°C, this would not be enough as the risk of triggering one or more global tipping points would still be more than 50%,” Wunderling said. “With more warming in the long-term, the risks increase dramatically.”

“We found that the risk for the emergence of at least one tipping event increases with rising peak temperatures—already at a peak temperature of 3°C, more than one-third of all simulations showed a tipping event even when overshoot durations were limited strongly,” he added. “At 4°C peak temperature, this risk extends to more than half of all simulations.”

According to the study, “Our model analysis reveals that temporary overshoots can increase tipping risks by up to 72% compared with non-overshoot scenarios, even when the long-term equilibrium temperature stabilizes within the Paris range.”

Study co-author Ricarda Winkelmann, co-lead of the FutureLab on Earth Resilience in the Anthropocene at PIK, pointed out that “especially the Greenland and the West Antarctic ice sheet are at risk of tipping even for small overshoots, underlining that they are among the most vulnerable tipping elements.”

“While it would take a long time for the ice loss to fully unfold, the temperature levels at which such changes are triggered could already be reached soon,” she said. “Our action in the coming years can thus decide the future trajectory of the ice sheets for centuries or even millennia to come.”

While these scientists found that the Amazon and AMOC have higher critical temperature thresholds, various studies have highlighted the dangers of either system reaching its tipping point.

An analysis of the Amazon released in September by scientists and Indigenous leaders in South America stated that “the tipping point is not a future scenario but rather a stage already present in some areas of the region,” meaning portions of the crucial rainforest may never recover—which could have “profound” consequences on a global scale.

A study on the AMOC from last year, also published in Nature Climate Change, warned that the collapse of the system of currents that carries warm water from the tropics to the North Atlantic “would have severe impacts on the global climate system,” from disrupting rains that billions of people need for food and increasing storms to further threatening the Amazon and ice sheets.

Donges stressed that “even though a temporary temperature overshoot would definitely be better than reaching a peak temperature and remaining there, some of the overshoot impacts may lead to irreversible damages in a high climate risk zone and this is why low-temperature overshoots are key here.”

Pointing to estimates that current policies could lead to an average global temperature of up to 3.6°C by 2100, Donges declared that “this is not enough.”

As Winkelmann put it: “Every tenth of a degree counts. We must do what we can to limit global warming as quickly as possible.”

‘We must trigger social tipping points’

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Photo by William Bossen on Unsplash
Photo by William Bossen on Unsplash

The risk of dangerous, cascading tipping points in natural systems escalates above 1.5°C of global warming, states a recent study.

By Yasmin Dahnoun, Ecologist (Creative Commons 4.0).

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

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

An international research team synthesized 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.

Die-off

The research concludes that we are already in the danger zone for five climate tipping points: melting of the Greenland and West Antarctic ice sheets, widespread abrupt permafrost thaw, the collapse of convection in the Labrador Sea, and massive die-off of tropical coral reefs.

The paper was published ahead of a major conference, Tipping Points: from climate crisis to positive transformation, at the University of Exeter, which will take place next week.

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

David Armstrong McKay, from Stockholm Resilience Centre, University of Exeter, and the Earth Commission, was the lead author of the report. He said: “We can see signs of destabilization 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.”

Safe

The Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), stated that risks of triggering climate tipping points become high by around 2°C above preindustrial temperatures and very high by 2.5-4°C.

The new analysis indicates that earth may have already left a “safe” climate state when temperatures exceeded approximately 1°C above preindustrial temperatures.

A conclusion of the research is therefore that even the United Nations’ Paris Agreement goal to avoid dangerous climate change by limiting warming to well below 2°C and preferably 1.5°C is not fully safe.

However, the study provides strong scientific support for the Paris Agreement and associated efforts to limit global warming to 1.5°C, as while some tipping points are possible or likely at this temperature level, the risk escalates beyond this point.

Liveable 

To have a 50 percent chance of achieving 1.5°C and thus limiting tipping point risks, global greenhouse gas emissions must be cut by half by 2030, reaching net zero by 2050.

Co-author Johan Rockström, the co-chair of the Earth Commission and director of the Potsdam Institute for Climate Impact Research, said: “The world is heading towards 2-3°C of global warming.

“This sets earth on course to cross multiple dangerous tipping points that will be disastrous for people across the world.

“To maintain liveable conditions on earth, protect people from rising extremes, and enable stable societies, we must do everything possible to prevent crossing tipping points. Every tenth of a degree counts.”

Decarbonising 

Tim Lenton, director of the Global Systems Institute at the University of Exeter and a member of the Earth Commission, was a co-author of the report. He said: “Since I first assessed climate tipping points in 2008, the list has grown and our assessment of the risk they pose has increased dramatically.

“Our new work provides compelling evidence that the world must radically accelerate decarbonizing the economy to limit the risk of crossing climate tipping points.

“To achieve that, we now need to trigger positive social tipping points that accelerate the transformation to a clean-energy future.

“We may also have to adapt to cope with climate tipping points that we fail to avoid, and support those who could suffer uninsurable losses and damages.”

Collapse

Scouring paleoclimate data, current observations, and the outputs from climate models, the international team concluded that 16 major biophysical systems involved in regulating the earth’s climate (so-called “tipping elements”) have the potential to cross tipping points where change becomes self-sustaining.

That means even if the temperature stops rising, once the ice sheet, ocean, or rainforest has passed a tipping point it will carry on changing to a new state.

How long the transition takes varies from decades to thousands of years depending on the system.

For example, ecosystems and atmospheric circulation patterns can change quickly, while ice sheet collapse is slower but leads to an unavoidable sea-level rise of several meters.

The researchers categorized the tipping elements into nine systems that affect the entire earth system, such as Antarctica and the Amazon rainforest, and a further seven systems that if tipped would have profound regional consequences.

Interlinked 

The latter include the West African monsoon and the death of most coral reefs around the equator.

Several new tipping elements such as Labrador Sea convection and East Antarctic subglacial basins have been added compared to the 2008 assessment, while Arctic summer sea ice and the El Niño Southern Oscillation (ENSO) have been removed for lack of evidence of tipping dynamics.

Co-author Ricarda Winkelmann, a researcher at the Potsdam Institute for Climate Impact Research and a member of the Earth Commission, said: “Importantly, many tipping elements in the earth system are interlinked, making cascading tipping points a serious additional concern.

“In fact, interactions can lower the critical temperature thresholds beyond which individual tipping elements begin destabilizing in the long run.”