Keeping global warming below 1.5°C is no longer plausible with CO2 emissions still increasing, according a new report, 2025 Global Carbon Budget, led by Professor Pierre Friedlingstein, of the University of Exeter’s Global Systems Institute.
The study projects a record high of 38.1 billion tons of fossil CO2 emissions this year. Published alongside a new paper in the journal Nature it finds that 8% of the rise in atmospheric CO2 concentration since 1960 is due to climate change weakening the land and ocean sinks.
The research team included the University of Exeter, the University of East Anglia (UEA), CICERO Center for International Climate Research, Ludwig-Maximilian-University Munich (LMU), Alfred-Wegener-Institut and more than 90 other institutions around the world.
“The remaining carbon budget for 1.5°C, 170 billion tonnes of carbon dioxide, will be gone before 2030 at current emission rate,” said Friedlingstein. “We estimate that climate change is now reducing the combined land and ocean sinks – a clear signal from Planet Earth that we need to dramatically reduce emissions.”
The ocean is the largest carbon sink, accounting for some 30% of carbon dioxide created by the burning of fossil fuels. However, the system was not designed to absorb the amount of CO2 humans continue to pump into the atmosphere. And there are potentially catastrophic changes brewing. For example, 40% of the ocean’s CO2 absorption is accounted to the Southern Ocean where vast amounts are stored at the ocean floor. But scientists now are concerned that changes in the ocean composition could bring that CO2 to the surface, thwarting the Southern Ocean’s ability to absorb atmospheric CO2.
“It is 10 years since the Paris Agreement was negotiated, and despite progress on many fronts, fossil CO2 emissions continue their relentless rise,” said Glen Peters, Senior Researcher at the CICERO Center for International Climate Research. “Climate change and variability are also having a discernible effect on our natural climate sinks. It is clear countries need to lift their game. We now have strong evidence that clean technologies help reduce emissions while being cost effective compared to fossil alternatives.”
Other key findings from the 2025 Global Carbon Budget include:
- China’s emissions in 2025 are projected to increase by 0.4% – growing more slowly than in recent years, due to a moderate growth in energy consumption combined with an extraordinary growth in renewable energy.
- India’s emissions are projected to increase by 1.4% – also slower than recent trends. An early monsoon reduced cooling requirements in the hottest months. Combined with strong growth in renewables, this led to very low growth in coal consumption.
- Emissions are projected to grow in the USA (+1.9%) and the European Union (0.4%) in 2025.
- Projected emissions in Japan, provided this year for the first time, are down 2.2% in line with recent trends.
- Emissions for the rest of the world are projected to increase by 1.1%.
- The projected rise in fossil CO2 emissions in 2025 is driven by all fuel types: coal +0.8%, oil +1%, natural gas +1.3%.
- Emissions are projected to increase by 6.8% for international aviation (exceeding pre-COVID levels) but to remain flat for international shipping.
- Over the 2015-2024 period, emissions from permanent deforestation remain high at around 4 billion tonnes of CO2 per year, while permanent removals through re/afforestation and forest regrowth offsets about half of the permanent deforestation emissions.
- Total CO2 emissions – the sum of fossil and land-use change emissions – have grown more slowly in the past decade (0.3% per year), compared to the previous decade (1.9% per year).
- The combined effects of climate change and deforestation have turned Southeast Asian and large parts of South American tropical forests from CO2 sinks to sources.
- The concentration of CO2 in the atmosphere is set to reach 425.7 ppm in 2025, 52% above pre-industrial levels.
