Window to avoid 1.5°C of warming will close before 2030 if emissions are not reduced, study shows
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Without rapid carbon dioxide emission reductions, the world has a 50% chance of locking in 1.5°C of warming before 2030, according to a study led by Imperial College London researchers.
The study, published in Nature Climate Change, is the most up-to-date and comprehensive analysis of the global carbon budget. The carbon budget is an estimate of the amount of carbon dioxide emissions that can be emitted while keeping global warming below certain temperature limits.
The Paris Agreement aims to limit global temperature increase to well below 2°C above preindustrial levels and pursue efforts to limit it to 1.5°C. The remaining carbon budget is commonly used to assess global progress against these targets.
The new study estimates that for a 50% chance of limiting warming to 1.5°C, there are less than 250 metric gigatons of carbon dioxide left in the global carbon budget.
The researchers warn that if carbon dioxide emissions remain at 2022 levels of about 40 metric gigatons per year, the carbon budget will be exhausted by around 2029, committing the world to warming of 1.5°C above preindustrial levels.
The finding means the budget is less than previously calculated and has approximately halved since 2020 due to the continued increase of global greenhouse gas emissions, caused primarily from the burning of fossil fuels as well as an improved estimate of the cooling effect of aerosols, which are decreasing globally due to measures to improve air quality and reduce emissions.
Dr. Robin Lamboll, research fellow at the Center for Environmental Policy at Imperial College London, and the lead author of the study, said, "Our finding confirms what we already know—we're not doing nearly enough to keep warming below 1.5°C.
"The remaining budget is now so small that minor changes in our understanding of the world can result in large proportional changes to the budget. However, estimates point to less than a decade of emissions at current levels.
"The lack of progress on emissions reduction means that we can be ever more certain that the window for keeping warming to safe levels is rapidly closing."