Global Carbon Budget 2026

Abstract. Accurate assessment of anthropogenic carbon dioxide (CO₂) emissions and their partitioning among the atmosphere, ocean, and terrestrial biosphere in a changing climate is critical to better understand the global carbon cycle, supporting the development of climate policies, and project future climate change. Here we describe and synthesise datasets and methodologies to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO₂ emissions (E_FOS) are based on energy and cement production data. Emissions from land-use change (E_LUC) are estimated by bookkeeping models based on land-use data. The global atmospheric CO₂ growth rate (G_ATM) is computed from changes in concentration measured at surface stations. The global net uptake of CO₂ by the ocean (S_OCEAN) is estimated with global ocean biogeochemistry models and observation-based fCO₂-products. The global net uptake of CO₂ by the land (S_LAND) is estimated with dynamic global vegetation models. Additional lines of evidence are provided by atmospheric inversions, atmospheric oxygen measurements, ocean interior observation-based estimates, and Earth System Models. The sum of all sources and sinks results in the carbon budget imbalance (B_IM), a measure of imperfect data and incomplete understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ.

For the year 2025, E_FOS increased by 1.2% relative to 2024, with fossil emissions at 10.5 ± 0.5 GtC yr^-1 (including the cement carbonation sink, 0.2 GtC yr^-1), E_LUC was 1.2 ± 0.7 GtC yr^-1, for total anthropogenic CO₂ emissions of 11.7 ± 0.9 GtC yr^-1 (42.8 ± 3.2 GtCO2 yr^-1). Also, for 2025, G_ATM was 4.4 ± 0.2 GtC yr^-1 (2.06 ± 0.1 ppm yr^-1), 3.6 GtC lower than the record high 2024 growth rate. S_OCEAN was 3.2 ± 0.7 GtC yr^-1 and S_LAND was 3.6 ± 0.9 GtC yr^-1, with a small B_IM (0.5 GtC yr^-1). The global atmospheric CO₂ concentration averaged over 2025 reached 425.6 ± 0.1 ppm. Preliminary data for 2026 suggest a decrease in E_FOS relative to 2025 of 0.40% (–1.5% to +0.6%) globally, and atmospheric CO₂ concentration increasing by 2.2 ppm reaching 427.7 ppm, 54% above the pre-industrial level (around 278 ppm in 1750). Overall, the mean and trend in the components of the global carbon budget are consistently estimated over the period 1959–2025, with a small positive overall budget imbalance, (0.6 GtC yr^-1 averaged over the period 1959–2025), although discrepancies of up to around 1 GtC yr^-1 persist for the representation of annual to decadal variability in CO₂ fluxes. Comparison of estimates from multiple approaches and observations shows: (1) a persistent large uncertainty in the estimate of land-use change emissions, (2) a low agreement between the different estimates on the magnitude of the land CO₂ flux, particularly in the northern extra-tropics, and (3) a discrepancy between the different estimates on the mean ocean sink and its trend.

This living data update documents changes in methods and datasets applied to this most-recent global carbon budget as well as evolving community understanding of the global carbon cycle. The data presented in this work are available at https://doi.org/10.18160/GCP-2026 (Friedlingstein et al., 2026b).