What is the current percentage of CO2 emissions from fossil fuel combustion?
Executive summary
Global carbon dioxide (CO2) emissions from fossil fuels are projected to reach a record 38.1 billion tonnes in 2025, a 1.1% increase over 2024, and fossil combustion continues to account for roughly nine‑tenths of human CO2 emissions according to the Global Carbon Project and restatements by research outlets [1] [2] [3]. Reporting also shows energy‑sector CO2 trends vary by region—advanced economies fell in 2024 while emerging markets rose—underscoring that global totals mask divergent national trajectories [4].
1. Record year: 38.1 billion tonnes and rising
The headline figure in the 2025 Global Carbon Budget is unambiguous: CO2 from fossil fuels and cement is projected to hit 38.1 billion tonnes in 2025, up about 1.1% from the prior year, setting a new record global high [1] [2]. Multiple universities and science outlets relay the same projection and the small growth is driven across coal (+0.8%), oil (+1%) and natural gas (+1.3%) [5] [6].
2. Share of total CO2 and the dominant role of fossil combustion
The Global Carbon Project and associated commentary emphasize that CO2 from fossil fuel use makes up the vast majority of anthropogenic CO2; one summary states fossil fuels account for about 90% of CO2 emissions—which is why changes in fossil combustion largely determine whether global emissions rise or fall [3]. Total CO2 in 2025—fossil plus land‑use change—is projected near 42.2 GtCO2, with fossil sources constituting the large bulk of that total [1].
3. Regional divergence: where emissions are rising and where they fell
The International Energy Agency’s 2025 review and the Global Carbon Budget show divergent regional patterns: energy‑related CO2 fell in many advanced economies in 2024 (IEA notes a 1.1% decline in advanced economies and large drops in coal use), while emerging markets saw a 1.5% rise driven by growing energy demand [4]. The Global Carbon Budget likewise flags continued increases in parts of the world even as others decarbonize [7].
4. Why the number matters: sinks, budgets and 1.5°C
Analysts warn that rising fossil CO2 undermines the remaining carbon budget for 1.5°C: the Global Carbon Budget frames the remaining budget as small (about 170 billion tonnes of CO2) and equivalent to only a few years at 2025 emission rates, highlighting urgency [2] [7]. The report also notes that climate impacts are weakening natural carbon sinks, which exacerbates the atmospheric accumulation of anthropogenic CO2 [8].
5. Sources, method and uncertainty
The 38.1 GtCO2 figure is a projection from the Global Carbon Project’s 2025 Global Carbon Budget and is reported across reputable outlets (Carbon Brief, TIME, university press releases), which also give an uncertainty range for the year‑on‑year change (for 2025 the GCB cites ~0.2–2.2% uncertainty around the 1.1% growth) [1] [8]. Different datasets (e.g., NOAA quoting the Global Carbon Budget 2024 baseline) show slight year‑to‑year differences in reported totals—37.4 GtCO2 for 2024 in one NOAA summary—so exact annual numbers can shift with methodology and updates [9].
6. Competing emphases: steady progress vs. continuing rise
Several sources frame the same data differently: university and science outlets emphasize record highs and the urgency to act [5] [6], while some institutional pieces (IEA) highlight where policy and renewable deployment have reduced emissions in parts of the world and stress the uneven pace of change [4]. Both perspectives are present in the reporting: progress is real in many countries, but global fossil CO2 is still increasing overall [6] [2].
7. Who’s responsible and hidden narratives
Investigations cited by The Guardian point out concentration of production: analyses show a relatively small set of fossil‑fuel companies account for a large share of produced carbon embedded in fuels—one study found 36 firms’ products were linked to more than 20 billion tonnes CO2 in 2023—an angle that shifts focus from individual emissions to upstream producers and policy choices [10]. That framing can carry an implicit agenda to target corporate production rather than only national consumption.
8. Limitations and what reporting does not say
Available sources do not mention a single, universally accepted “percentage of CO2 emissions” from fossil fuels for every possible denominator (e.g., share of all greenhouse gases, or share of cumulative vs annual emissions) beyond the frequent summary that fossil fuel use supplies roughly 90% of CO2 emissions; precise percentages depend on definitions and datasets [3] [1]. Also, longer‑term projections beyond 2025 are not in these excerpts, so future trend assessments require more data.
Conclusion: the evidence in the 2025 Global Carbon Budget and corroborating coverage is consistent and decisive—fossil fuel combustion remains the dominant source of CO2, projected at a record 38.1 GtCO2 in 2025 [1] [2], and this persistent rise, concentrated in certain regions and producers, is the central barrier to staying within the 1.5°C carbon budget [2] [10].