The carbon budget remaining to limit the climate crisis to 1.5C of global heating is now “tiny”, according to an analysis, sending a “dire” message about the adequacy of climate action.
The carbon budget is the maximum amount of carbon emissions that can be released while restricting global temperature rise to the limits of the Paris agreement. The new figure is half the size of the budget estimated in 2020 and would be exhausted in six years at current levels of emissions.
Temperature records have been obliterated in 2023, with extreme weather supercharged by global heating hitting lives and livelihoods across the world. At the imminent UN Cop28 climate summit in the United Arab Emirates there are likely to be disputes over calls for a phaseout of fossil fuels.
The analysis found the carbon budget remaining for a 50% chance of keeping global temperature rise below 1.5C is about 250bn tonnes. Global emissions are expected to reach a record high this year of about 40bn tonnes. To retain the 50% chance of a 1.5C limit, emissions would have to plunge to net zero by 2034, far faster than even the most radical scenarios.
The current UN ambition is to cut emissions by half by 2030 and reach net zero by 2050, although existing policies are far from delivering this ambition. If it was achieved, however, it would mean only about a 40% chance of staying below 1.5C, the scientists said, so breaking the limit would be more likely than not.
But, they warned, every 10th of a degree of extra heat caused more human suffering and therefore keeping as close as possible to 1.5C was crucial.
The new carbon budget estimate is the most recent and comprehensive analysis to date. The main reasons the budget has shrunk so markedly since 2020 are the continued high emissions from human activities and a better understanding of how reducing air pollution increases heating by blocking less sunlight. [Continue reading…]