Achieving carbon neutrality by the end of the century is crucial for maintaining the long-term stability of our planet and preventing catastrophic consequences, researchers warn in a study published on Thursday.
The current climate policies are insufficient to prevent the risk of crossing certain “tipping points,” critical thresholds beyond which systems reorganize abruptly or irreversibly, leading to a cascade of effects.
This includes phenomena such as the melting of ice sheets and changes in ocean currents.
The Critical Role of Current Actions
“What we do now matters for decades, centuries, and even millennia to come,” states Nico Wunderling from the Potsdam Institute for Climate Impact Research (PIK), one of the authors of the study published in Nature Communications.
The world is on track to exceed the 1.5°C warming threshold above pre-industrial levels, the most ambitious limit set by the 2015 Paris Agreement, which aims to keep warming “well below 2°C.”
Risks of Exceeding 1.5°C
Exceeding this limit permanently would substantially increase the likelihood of triggering tipping points, such as the disappearance of the Amazon rainforest or the melting of the Greenland and West Antarctic ice sheets.
However, this risk can be reduced “if warming is rapidly reversed,” even if the 1.5°C threshold is temporarily breached, according to the researchers. This would require rapid measures to reduce greenhouse gas emissions to fall back below the 1.5°C threshold by the end of the century.
Necessity of Achieving Carbon Neutrality by 2100
“Such a reversal in global warming can only occur if at least carbon neutrality is achieved by 2100,” said Nico Wunderling. Carbon neutrality entails a balance between residual CO2 emissions and their absorption by carbon sinks like forests, which are currently under threat.
“Heads or Tails”
“Achieving and maintaining at least net zero greenhouse gas emissions by 2100 is crucial to minimize long-term tipping risks,” the study concludes. As things stand, the full implementation of unconditional state promises under the Paris Agreement puts the world on a path to 2.9°C warming this century, according to UN calculations.
Conditional promises reduce this rise to 2.5°C. Both levels are far too high to avoid catastrophic effects. Each additional 0.1°C increase above 1.5°C raises the possibility that at least one of the four elements of planetary equilibrium (the Amazon rainforest, Atlantic ocean circulation, Greenland ice sheets, and West Antarctic ice sheets) will collapse by 2300. This trend “accelerates sharply” beyond 2°C of warming.
The Unacceptable Risk of Current Warming Trends
The current trend of warming represents “an unacceptable risk to our climate system,” Nico Wunderling told AFP. “It’s like flipping a coin.”
“The most important thing now is to keep global warming as low as possible… and then return to 1.5°C as soon as possible,” he explains. The study “highlights the fact that significant emission reductions in this decade are critical for planetary stability,” the researchers say, emphasizing the importance of meeting the Paris Agreement goals.