Global Carbon Budget 2020

Background

“Global Carbon Budget 2020” quantifies the carbon dioxide (CO2) budget through 2019 and provides a 2020 projection, capturing the emissions drop associated with the COVID-19 pandemic. Atmospheric CO2 nevertheless continues to rise, reflecting the cumulative effect of past emissions and the fact that sinks absorb only part of the annual anthropogenic CO2.

Goals and Methods

This study estimates fossil and cement emissions, land-use change emissions, atmospheric CO2 growth, and land and ocean sinks for 1959–2019, with decadal detail and an outlook for 2020. For fossil emissions, the combined Carbon Dioxide Information Analysis Center (CDIAC), UNFCCC, BP, and cement datasets were used, and bookkeeping models driven by updated land-use histories were used for land-use change emissions. Land and ocean sinks data were derived from process-based ocean and land models.

Conclusions and Takeaways

For 2010-2019, average fossil emissions reached about 9.6 GtC yr⁻¹, land-use change emissions averaged around 1.5 GtC yr⁻¹, and land and ocean sinks grew to ~3.4 and ~2.5 GtC yr⁻¹, respectively, leaving a growth in atmospheric CO2 around 4.9 GtC yr⁻¹. In 2019, fossil emissions hit a record high (≈10 GtC yr⁻¹), but 2020 projections indicate a significant temporary decline due to pandemic-related restrictions, without yet implying a structural shift toward sustained decarbonization. For practitioners, the 2020 budget offers a key case study on how large, but short-lived, shocks affect emissions trajectories and sinks, and it underlines the need for deliberate policy to convert transient drops into long-term declines.