The global carbon budget 1959–2011

Background

“The global carbon budget 1959-2011” synthesizes more than five decades of anthropogenic Carbon dioxide (CO2) perturbations to the global carbon cycle, from early industrialization to contemporary high-emission conditions. It documents atmospheric CO2 increasing from about 278 ppm in 1750 to 391.31 ± 0.13 ppm by the end of 2011, with fossil fuel combustion replacing land-use change as the dominant source from around 1920. The paper frames these trends within persistent natural exchanges among atmosphere, ocean, and land, which are overlaid by human-driven emissions.

Goals and Methods

The study aims to quantify annual fossil emissions (EFF), land-use change emissions (ELUC), atmospheric growth (GATM), and land (SLAND) and ocean (SOCEAN) sinks for 1959–2011, including uncertainties and methodological consistency. EFF is calculated using Carbon Dioxide Information and Analysis Center (CDIAC)-based national energy and cement data, extended for recent years via BP energy statistics, while ELUC uses FAO forest data, wood harvest statistics, shifting cultivation, and GFED fire emissions to capture management–climate interactions. Atmospheric CO2 growth comes from Scripps and NOAA/GML networks, the ocean sink is constrained by 1990s observational estimates and ocean models, and the residual land sink is inferred as the budget remainder and compared with dynamic global vegetation models.

Conclusions and Takeaways

For 2011, this paper reports fossil emissions of 9.5 ± 0.5 PgC yr⁻¹, land use change emissions of 0.9 ± 0.5 PgC yr⁻¹, atmospheric CO2 growth of 3.6 ± 0.2 PgC yr⁻¹, an ocean sink of 2.7 ± 0.5 PgC yr⁻¹, and a large land sink of 4.1 ± 0.9 PgC yr⁻¹ linked to La Niña enhanced uptake. Over 2002–2011, average fossil emissions are 8.3 ± 0.4 PgC yr⁻¹ and land use change emissions 1.0 ± 0.5 PgC yr⁻¹, with sinks and growth closing the budget within stated uncertainties, though land-use emissions remain comparatively uncertain. The authors conclude that the framework provides a robust annual benchmark for tracking progress, diagnosing sink variability, and supporting climate policy design, while calling for improved land-use data, freshwater-coastal carbon flux quantification, and multiple independent budget approaches.