Global Carbon Budget 2016

Background

“Global Carbon Budget 2016” extends the budget through 2015 and provides preliminary 2016 fossil emission estimates, marking the period when global atmospheric carbon dioxide (CO2) surpassed 400 ppm. Atmospheric concentration increases from about 277 ppm in 1750 to 399.4 ± 0.1 ppm in 2015, with global monthly means above 400 ppm in multiple months. This study emphasizes that fossil fuel emissions remain the dominant anthropogenic source, while land-use change continues to contribute a smaller but persistent share.

Goals and Methods

This paper aims to quantify decadal and annual fossil and land-use change emissions, atmospheric CO2 growth, and land and ocean sinks for 1959–2015, to evaluate sink variability, and to project 2016 fossil emissions. Fossil and industrial emissions are derived from the Carbon Dioxide Information and Analysis Center (CDIAC) and energy statistics, supplemented by projections based on GDP growth and changes in carbon intensity, while emissions from land use are estimated from land-cover change, deforestation, fires, and bookkeeping models. Atmospheric growth uses NOAA/Scripps data; the ocean sink is constrained by 1990s observations with anomalies from ocean models and fCO2 (fugacity of carbon dioxide) data products; and the residual land sink is cross-checked with independent dynamic global vegetation models and atmospheric inversions across latitude bands.

Conclusions and Takeaways

For 2006-2015, mean fossil and industrial emissions were 9.3 ± 0.5 GtC yr⁻¹ and land-use change emissions were 1.0 ± 0.5 GtC yr⁻¹, balanced by atmospheric growth of 4.5 ± 0.1 GtC yr⁻¹, an ocean sink of 2.6 ± 0.5 GtC yr⁻¹, and a land sink of 3.1 ± 0.9 GtC yr⁻¹. In 2015, fossil emissions were 9.9 ± 0.5 GtC yr⁻¹ with essentially zero growth, land-use change emissions rose to 1.3 ± 0.5 GtC yr⁻¹, and a weakened land sink of 1.9 ± 0.9 GtC yr⁻¹ contributed to a high atmospheric growth of 6.3 ± 0.2 GtC yr⁻¹, influenced by El Niño conditions. Preliminary 2016 projections indicate very low fossil emission growth (~+0.2%, −1.0 to +1.8%) and cumulative 1870-2016 emissions of about 565 ± 55 GtC, providing a near real-time benchmark for evaluating emerging peaking signals, sink sensitivity to climate variability, and progress relative to remaining carbon budgets.