The Global Carbon Budget (GCB), coordinated by the Global Carbon Project (GCP) under the auspices of Future Earth, provides a comprehensive assessment of the global carbon cycle. GCB synthesizes multiple datasets and methodologies annually to quantify fossil-fuel CO2 emissions, land-use change emissions, atmosphericCO2 growth, and the land and ocean carbon uptakes. The assessment integrates bottom-up methods (e.g., inventories, land-use and ecosystem models, ocean biogeochemical models) with top-down atmospheric inversions that reconcile surface fluxes with observed atmosphericCO2. The 2025 edition marks the 20th year of GCB (Friedlingstein et al., 2025), first published in 2006.
Since the atmospheric CO2 inversion fluxes by Dr. Prabir K. Patra in 2018, JAMSTEC’s involvement in GCB continues to build on earlier contributions. For the 2025 edition (Friedlingstein et al., ESSD, 2025), Dr. Naveen Chandra contributed atmosphericCO2 flux estimates using inverse modelling, and Dr. Hiroaki Tatebe provided bottom-up estimates of global carbon cycle variations using a coupled Earth System model and data assimilation framework as co-authors. Here, it is also noted that the high-performance computing systems in JAMSTEC, including the Earth Simulator (ES4), were central to producing these estimates.
The 2025 budget suggests that global fossil-fuelCO2 emissions are projected to grow by 1.1% in 2025 with respect to the 2024 level, despite ongoing decarbonization efforts. Following the end of the 2023–24 El Niño event, this year is expected to see the terrestrial carbon sink recovering toward pre-El Niño conditions. Nevertheless, the analysis shows that climate change is tending to weaken the totalCO2 sinks on the Earth’s surface, calling for accelerated mitigation of anthropogenic emissions to achieve stabilization of atmospheric CO2 concentration.
·The Global Carbon Project (GCP) releases the Global Carbon Budget 2025
（Global Carbon Project Tsukuba International Office）
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