In a sobering analysis, scientists reveal that the carbon budget, the allowable amount of carbon emissions to maintain global warming within the 1.5°C limit specified in the Paris Agreement, has shrunk to a critically low level. This dire revelation underscores the inadequacy of current climate action measures.
The updated carbon budget, a benchmark for global action, is now merely half of the estimate from 2020. At the current rate of emissions, this budget will be depleted within a mere six years. The year 2023 has already seen unprecedented temperature records shattered, with extreme weather events wreaking havoc across the world due to exacerbated global heating.
As the imminent UN Cop28 climate summit approaches in the United Arab Emirates, contentious debates over the necessity of phasing out fossil fuels are expected.
The analysis underscores that to have a 50% chance of restraining global temperature rise below 1.5°C, the remaining carbon budget is approximately 250 billion tonnes. With global emissions on track to hit a record 40 billion tonnes this year, drastic and rapid reductions are imperative to maintain the 1.5°C target. Net-zero emissions must be achieved by 2034, a pace even more ambitious than the boldest scenarios.
While the current UN goal is to halve emissions by 2030 and reach net zero by 2050, prevailing policies are far from achieving this ambition. Even if these objectives are met, there is only a 40% chance of staying below 1.5°C, as per scientists’ assessments, making it more likely to surpass the limit.
The study underscores that each tenth of a degree of additional warming results in heightened human suffering, emphasizing the crucial need to remain as close as possible to the 1.5°C target.
This updated carbon budget assessment is the most comprehensive to date. The primary reasons behind the drastic reduction since 2020 are the persistently high emissions from human activities and an improved understanding of how reduced air pollution amplifies heating by permitting more sunlight to penetrate.
Prof. Joeri Rogelj, one of the study’s authors from Imperial College London, UK, describes the situation as “dire” and notes that the 50% or higher likelihood of limiting warming to 1.5°C is slipping away, regardless of political or policy efforts. The perilous level of risk humanity seems willing to endure is striking.
Dr. Chris Smith, from the International Institute for Applied Systems Analysis in Austria, states that governments have the ability to control emissions but have not done so adequately. The ongoing shrinking of the carbon budget is a reflection of this reality. The study does not suggest that the world has only six years to solve climate change; however, it emphasizes the urgency of the situation and the need for decisive action.
The analysis, published in the journal Nature Climate Change, used updated data and improved climate models compared to recent estimates. It also considered the impact of aerosol air pollution and its role in blocking sunlight and limiting heating. As pollution decreases, the risk of increased global heating grows, thereby reducing the carbon emissions budget to stay below 1.5°C.
The study also assessed the upper limit of 2°C in the Paris Agreement, highlighting that even if this limit is met, it would lead to a significant increase in climate-related impacts, from heatwaves to floods and crop losses.
To maintain a 90% chance of staying below 2°C, emissions must reach net zero by about 2035. Achieving net zero by 2050 would provide a 66% chance of meeting the 2°C target.
This alarming carbon budget data presents a significant challenge to policymakers, as it implies that achieving net-zero CO2 emissions by 2034 is far more ambitious than current global climate policies.
Dr. Gabriel Abrahão, from the Potsdam Institute for Climate Impact Research in Germany, raises the possibility of overshooting the 1.5°C target in this decade, prompting a need for discussions on how to return to 1.5°C after an overshoot.
The researchers acknowledge the significant uncertainties involved in calculating the carbon budget, and they aim to provide annual updates on the remaining budget.
Recent data from the International Energy Agency suggests that global carbon emissions from fossil fuel burning could peak as early as this year, potentially leading to emissions reductions starting in 2024.
This sobering assessment underscores the urgent need for decisive global action to combat climate change and limit global warming, emphasizing the critical importance of staying as close as possible to the 1.5°C target.