The good news: Long-term pledges that nations have made to cut greenhouse gas pollution have the collective potential to avoid some of the most catastrophic impacts of climate change.
This is the first peer-reviewed analysis to show that the world has a better-than-even chance of limiting temperature rise to 2 degrees Celsius (3.6 degrees Fahrenheit) above preindustrial levels if nations follow through on their current commitments — a significant sign of progress from only a few years ago.
“But now the real work has to start,” said co-author Christophe McGlade, head of the Energy Supply Unit at the International Energy Agency in Paris, noting that countries must quickly embrace the massive investments and key policy changes that can start bringing down emissions.
“Policymakers are at a crossroads,” McGlade said. “We can choose to lock in emissions and deepen the energy crisis, or we can use this moment to take an earnest step toward a cleaner, safer future.”
Researchers analyzed the many climate plans that nations submitted leading up to last fall’s international climate summit in Glasgow, Scotland, known as COP26. There, two weeks of high-profile talks resulted in a deal that encourages countries to strengthen near-term climate targets and move away from fossil fuels faster. Scores of countries also made promises to rein in deforestation, cut emissions of the potent greenhouse gas methane and phase out financing for coal projects.
Despite the fanfare, the event did not achieve what would be necessary to meet the most ambitious goal of the 2015 Paris accord — limiting Earth’s warming to 1.5 degrees Celsius (2.7 Fahrenheit). Delegations left the COP26 summit still on pace to fuel a world of intensifying heat, widespread disease, severe food shortages and escalating climate disasters.
If countries follow through on their long-term pledges to zero out emissions by the middle of the century, the Nature analysis found, the world has just over a 50 percent chance of limiting warming to 2 degrees Celsius. The likelihood of hitting the 1.5 Celsius target is between 6 and 10 percent, unless countries adopt substantially bolder climate actions this decade.
Uncertainty about how the planet will respond to rising temperatures means there is still a small chance that Earth could warm 2.8 degrees Celsius (5 degrees Fahrenheit) by the end of the century, even if humanity fulfills its promises.
Actually achieving any long-term targets, the scientists say, will require nations to significantly boost their efforts today. Many countries have pledged relatively modest reductions in emissions by the end of the decade, meaning they would have to follow an improbably steep downward trajectory after 2030 to have a shot of achieving their mid-century goals.
Meanwhile, the policies and investments that governments have enacted paint an even grimmer picture. A sweeping report published last week by the United Nations Intergovernmental Panel on Climate Change (IPCC) found that current policies put global emissions on track to be 14 percent higher in 2030 than they are today.
“There is a huge difference between government rhetoric and reality,” experts warned in an online post from Climate Action Tracker, an independent international collaboration of climate scientists.
“No single large-emitting country has yet put policies in place to set emissions on a trajectory to meet its long-term, 2050 target,” the group wrote. It added that the promises through 2030 would only stabilize global emissions, rather than bring the sharp reductions that scientists have said are necessary in coming years.
In an analysis accompanying Wednesday’s Nature paper, climate scientists Zeke Hausfather and Frances Moore wrote that the latest national climate plans have moved the world away from some of the grimmest futures that were predicted if leaders took little meaningful action.
At the same time, the pair underscored what the most recent reports from the IPCC have all but confirmed — that the most lofty goal of the Paris agreement, to limit warming to 1.5 Celsius above preindustrial levels, is “slipping out of reach” without rapid and unprecedented changes.
Since August, the IPCC has issued three lengthy and sobering assessments of the world’s dangerous warming trajectory. The first detailed the extraordinary changes humans have wrought on the planet, fueling an increase in carbon dioxide to levels not seen in millions of years. The second documented the profound impacts already unfolding in a warming world, and the rising seas, more intense heat waves and droughts, and other disasters that lie ahead. The most recent outlined how the world is on pace to blaze past its climate goals unless it can harness the collective will to rapidly change course.
The findings brought renewed pleas from developing nations — which have done little to cause global warming but already are suffering its consequences — for the developed world to finally act with more urgency.
“Our chances to achieve sustainable development are fundamentally undermined by the inaction of big emitters. This must change,” Madeleine Diouf Sarr, chair of the Least Developed Countries, a group that negotiates as a bloc at international climate talks, said in a statement this month. “Countries must bring forward new and increased emissions reduction targets for this critical decade this year.”
The study authors note that many near-term pledges from developing countries are conditional upon receiving financial and technical assistance from wealthier parts of the world. This has been a major sticking point in international climate negotiations, with low-income regions saying they need help not just for building renewable-energy systems but also for adapting to climate impacts and recovering from disasters that have already occurred.
“These negotiations won’t be fruitful if it is a mere emissions reduction agenda [set] by developed countries,” said lead author Malte Meinshausen, a climate scientist at the University of Melbourne in Australia. “Climate finance is seen as an integral part of the solution mix and is necessary … to achieve stronger commitments from all parties.”
Few have implored leaders as urgently to do more — or spoken as bluntly about their failures on climate action — as U.N. Secretary General António Guterres.
When the IPCC released its latest assessment, detailing the world’s trajectory toward more emissions and more warming, Guterres called the findings “a litany of broken climate promises” that catalogue “the empty pledges that put us firmly on track towards an unlivable world.”
“Some government and business leaders are saying one thing but doing another,” Guterres said at the time. “Simply put, they are lying. And the results will be catastrophic.”