This year's Global Carbon Budget has revealed that carbon dioxide (CO₂) emissions from fossil fuel use are projected to rise by 1.1 per cent in 2025, reaching 42.2 billion tonnes in the atmosphere, although emissions from land-use are expected to decrease.
The Global Carbon Budget is produced by leading research international organisations, including CSIRO, Australia's national science agency, as part of the Global Carbon Project. It provides an overview of the global carbon budget, including both natural and human-induced emissions, and sinks.
CSIRO's Dr Pep Canadell, Global Carbon Project Executive Director, said CO₂ is a long-lived greenhouse gas that persists in the atmosphere for up to thousands of years, making it the single most important greenhouse gas contributing to human-induced climate change.
"The Global Carbon Budget shows that the use of fossil fuels accounts for about 90 per cent of all CO₂ emissions," Dr Canadell said.
"We expect all emissions from human activities this year to release a total of 42.2 billion tonnes of CO₂, leading to 52 per cent more CO₂ in the atmosphere than pre-industrial levels.
"However, total anthropogenic CO₂ emissions have grown more slowly than fossil CO₂ emissions alone in the past decade due to a decrease in global CO₂ emissions from land-use, such as a reduction in deforestation, degradation and revegetation."
Key findings
- Carbon dioxide (CO₂) emissions from fossil fuel use are projected to rise 1.1 per cent during 2025, the same level of increase than in 2024. However, total anthropogenic CO₂ emissions have grown more slowly in the past decade.
- The projected 2025 rise is driven by growth in all fuel types (coal, oil, and gas).
- Emissions in China (32 per cent of global emissions) and India (8 per cent of global emissions), are projected to be less in 2025 compared to their growth over the past decade. Emissions in the USA (13 per cent of global emissions), and European Union (6 per cent of global emissions), are projected to increase in 2025, partly influenced by weather conditions.
- Global CO₂ emissions from land-use change are expected to decrease in 2025, driven by reductions in deforestation and degradation fires in South America. Land-use change emissions have decreased since their peak in the late-1990s, particularly in the past decade.
- Natural CO₂ sinks, which is when CO₂ is absorbed by land and oceans, are set to recover to pre-El Niño strength in 2025, after a strong decrease in 2024, with land absorbing 21 per cent, and the ocean absorbing 29 per cent of anthropogenic emissions in the past decade.
Although there has been an increase in emissions from fossil fuels, there is continued progress in many countries in reducing or slowing emissions.
"The growth in fossil emissions has been partially offset by the decrease in land-use change emissions," Dr Canadell said.
"After a large decline of the natural CO₂ sinks in 2024 due to El Niño and high ocean temperatures, the land sink has recovered this year, showing the high sensitivity of the sinks to global warming and their likely reduction in the future.
"There are 35 countries with declining CO₂ emissions over the past decade while growing their economy, showing that decarbonisation pathways are on the way in many countries. However, their emission reductions have not enough to offset the global growth in energy demand.
"We need to accelerate the pace of emission reductions to manage the negative impacts of climate change."
For a 50 per cent likelihood to limit warming below 1.5°C, the remaining budget is 170 billion tonnes of CO₂, equivalent to four years at the 2025 emissions levels.
The remaining carbon budgets to limit warming to 1.7°C and 2°C above the 1850-1900 level have been reduced to 525 GtCO₂ (12 years at 2025 emissions levels) and 1055 GtCO₂ (25 years), respectively.
The Global Carbon Budget 2025 was launched today at COP30, the United Nations Climate Change Conference in Belèm, Brazil. It is the 20th edition of the annual update that started in 2006.
A Nature paper published this week showcases the science advances and observations in modelling and data to produce the robust estimates for the report.
Key highlights are:
- The magnitude of the natural land CO₂ sink is substantially smaller than previously estimated, while net emissions from anthropogenic land-use change are revised upwards.
- The ocean sink is 15 per cent larger than the land sink, consistent with new evidence from ocean and atmospheric observations.
- Climate change reduces the efficiency of the natural CO₂ sinks, particularly on land, contributing an additional 8.3 parts per million of CO₂ in the atmosphere since 1960.
The Global Carbon Budget is supported with funding from the Australian Government under the National Environmental Science Program's Climate Systems Hub.
Full details of the 2025 Global Carbon Budget are available in Earth System Science Data .
