When they met at the Cop21 UN climate summit in Paris in December 2015, world leaders pledged keep the rise in global temperatures to no more than 2 degrees Celsius over pre-industrial levels, and to aim for 1.5 degrees.
Monday’s report, prepared by the UN’s Intergovernmental Panel on Climate Change, presents research into what those targets mean, and climate scientists have emphasised their importance.
“The impacts of 1.5 and 2 degrees, which we didn’t know a lot about before this report, are actually quite different,” says Christopher Weber, global climate and energy lead scientist with the World Wildlife Fund.
“We know now that the impacts at 2 degrees are going to be much worse than we originally thought back when the Paris agreement was forged back in 2015.”
The world is currently 1 degree hotter than preindustrial levels, meaning there’s only half a degree left to ward off the worst of droughts, flooding, extreme heat and poverty.
The report estimates efforts to reach the 1.5 degree target have to happen within twelve years, and authors are warning they involve an expensive overhaul of the world economy.
“It means deep emission reductions in all sectors, the use of wide range of technologies, behaviour changes, and a significant investment in low carbon options,” said Jim Skea, one of the reports authors, as he presented the findings in South Korea.
“Rapid progress is already being made in some of the areas notably renewable energy, but this progress needs to be picked up in other areas such as transport and land management,” he continued.
“The pledges that governments have made over the last three years are not enough to keep warming below 1.5 degrees.”
Challenges of global politics
The report comes two months from the 24th UN climate conference in Katowice, Poland, and will pressure leaders to go much further than they did in Paris three years ago.
“The Cop24 in Poland will be the best opportunity we have to ensure that, all over the world, governments come up with increased ambitions and strong will to reduce their CO2 emissions as fast as they can,” says Jean-François Julliard, executive director of Greenpeace France.
“At the Cop21 in Paris, countries all over the world came up with their commitments, the NDCs [Nationally Determined Contributions], and they have to ramp up these ambitions, because we know for sure now that if we keep on the same track, we won’t reach the [1.5 degree] objective.”
Many nations are behind in their progress though, and with Donald Trump seeking to pull the United States out of the Paris deal, some appear to be going in the opposite direction.
However, campaigners also say that leaders are facing growing pressure to make meaningful changes.
“Political will is important, and around the world, in Europe for example, we see people standing up, going in the streets, really up for having a new energy system in particular,” says Susann Scherbarth of environmental group Friends of the Earth.
“It’s quite amazing and inspiring that people have the solutions in their hands, but we don’t see politicians and the fossil fuel industry acting in the same way.”
The report also warns that if nothing is done, the 1.5 mark could be reached by 2030, and temperatures would continue to rise up to 4 degrees in all.