According to a significant academic study, any violation of the limits on global warming agreed upon by climate scientists could lead to “irreversible consequences” for our planet.
Temporarily surpassing the 1.5°C threshold before reducing temperatures—a situation referred to as an “overshoot”—might lead to sea level rises and other severe effects that could persist for millennia.
Carl-Friedrich Schleussner, the leader of the study co-authored by 30 researchers, stated that this “disproves the idea that overshoot results in a comparable climate outcome” to a scenario where proactive measures are taken earlier to mitigate global warming.
The findings, which took three years to compile, are pressing, as the target of limiting global temperature increases to 1.5°C above pre-industrial levels is becoming increasingly elusive.
At present, however, temperatures are still on the rise.
Scientists and policymakers are increasingly regarding some form of temperature overshoot of 1.5°C as inevitable.
This newly published study in the peer-reviewed journal Nature warns against “overconfidence” in such scenarios, as the associated dangers may not yet be fully understood.
The researchers caution that an overshoot could result in consequences lasting hundreds, if not thousands, of years or trigger “tipping points” that could lead to significant and irreversible changes within Earth’s climate system.
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This could lead to the thawing of permafrost and peatlands, which are carbon-rich ecosystems that would emit substantial quantities of greenhouse gases if destroyed.
Moreover, the authors noted that sea levels could increase by an additional 40 cm if the 1.5°C mark is exceeded for a century—an existential threat to low-lying island nations.
“For nearly all climate metrics, there are irreversible consequences resulting from the temporary exceedance of, for example, the 1.5-degree limit,” explained Mr. Schleussner from the International Institute of Applied Systems Analysis based in Austria.
“Even if global temperatures are brought back down, the world we are facing will be different from that which would exist without an overshoot.”
Act now
The United Nations reports that the current climate action pledges would lead to nearly 3°C of warming by 2100.
Achieving the 1.5°C target necessitates net-zero emissions by 2050, requiring a balance between the amount of carbon dioxide emitted and the amount that can be extracted from the atmosphere through technology.
This carbon removal process must be significantly enhanced to lower global temperatures in the case of an overshoot, a goal that remains uncertain.
The authors indicated, “We cannot be assured that a decrease in temperature after an overshoot is achievable within the expected timeframes today.”
Mr. Schleussner emphasized that their findings highlight “the critical need for governments to act on reducing emissions immediately, rather than postponing, to minimize peak warming as much as possible.”
“To effectively limit climate risks, the push towards net zero needs to be recognized for what it truly is,” he stated.
