For the first time, the world is able to limit global warming to below 2C, according to the first in-depth analysis of the net zero promises made by nations at the UN Cop26 climate summit in December.
Prior to these promises, it was more than likely that at the height of the climate crisis there would be a temperature rise above 2C, which would have more serious consequences for billions of people. Now it is more likely that the maximum temperature rise will be around 1.9C.
But the researchers said this depended on all nations implementing their promises on time and in full, warning that policies to do so were out of place. The promises also include those that developing countries have said will not happen without more financial and technical support.
Achieving the promises needed for the 2C limit was a “historic milestone” and good news, the researchers said. However, they said the bad news was that the cuts in global emissions currently planned for 2030 were far off track to keep the peak below 1.5C. That is the global goal, but at the moment there is less than a 10% chance of achieving that goal.
Humans across the planet are already facing intensifying heat waves, floods and storms with the 1.2 C heat caused by human emissions to date, and the Intergovernmental Panel on Climate Change (IPCC) warned in 2018 of far worse if warming continues over 1.5 C.
The 2C limit that was within reach was “big news,” said Christophe McGlade of the International Energy Agency, a member of the team behind the new analysis. “This is the first time that governments have come up with specific goals that can keep global warming below the symbolic 2C level.”
“These results are clearly a cause for optimism,” he added. “We have come a long way since the Paris Agreement was signed back in 2015. But now the real work must begin. The promises have not yet been supported by the strong and credible short-term policies needed to make them a reality. “
Prof Malte Meinshausen at the University of Melbourne, Australia, another team member, said having the 2C limit in mind was a “historic milestone”.
But he said: “Our study also clearly shows that increased action in this decade is needed. Otherwise, we will blow through the remaining carbon budget of 1.5 C.” A major IPCC report earlier in April said global emissions should peak and begin to fall within 30 months to keep the 1.5C target alive.
The new analysis, published in the journal Nature, is the first peer-reviewed study to assess the highest temperature rise that would result from countries meeting their promises. It used two independent modeling methods, one of which assessed more than 1,400 different scenarios and included recent promises on shipping and aviation emissions.
By the end of Cop26, 153 nations had made new climate commitments to the UN, with countries responsible for 75% of global greenhouse gas emissions committing to reaching net zero between 2050 and 2070. These have made the 2C limit an option , although scientists warned that uncertainty about how the planet would react to rising emissions meant that there remained a 5% chance of a temperature above 2.8 C.
The climate policies actually in place today would mean a peak of around 2.6 C, leading to “massive climate damage around the world,” McGlade said. The commitments made by the countries until 2030 have only reduced this peak to 2.4 ° C. The IPCC has said that limiting heating to 1.5 C requires a 45% reduction in CO2 emissions by 2030 compared to 2010.
But emissions were set to rise by 7-15% by 2030, a “sober assessment”, the researchers said, with any delay in action that put 1.5C “out of reach”. If the world exceeds this goal, securing a “viable future” will depend on a massive roll-out of technology that can suck CO2 from the air, as well as large-scale replanting.
The new research provided a much clearer picture of our likely climate future, said Frances Moore of the University of California and Zeke Hausfather, the head of climate research at Stripe, in a commentary in Nature. They said it showed that the goal of raising the first climate pledges given in 2015 in Paris had been “partially realized”.
“But optimism should be dampened until promises to reduce emissions in the future are backed by stronger short-term actions,” they said. “It’s easy to set ambitious climate targets for 30, 40 or even 50 years into the future, but it’s much harder to implement policies. [needed] Today.”
Moore and Hausfather also warned of the danger of geopolitical tensions, including Russia’s war in Ukraine: “It would be a mistake to rule out a future of resurgent nationalism that strains global cooperation and leads to increasing dependence on domestic fossil fuel resources and a similar increase in emissions. “
“Police officers 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 honest step towards a cleaner and more secure future. “
McGlade said there were many policies that could have an immediate or short-term impact on the energy and climate crises, including reducing speed limits on roads, speeding up the roll-out of renewable energy and electric vehicles and stopping the venting of methane, a powerful greenhouse gas . , from oil and gas production plants and put it in supply instead.