Global CO2 emissions have been flat for a decade, new data reveals

By Zeke Hausfather. Zeke Hausfather has a PhD in climate science from the University of California, Berkeley. Excerpt:

"The Global Carbon Project (GCP) projects that fossil emissions in 2021 will reach 36.4bn tonnes of CO2 (GtCO2), only 0.8% below their pre-pandemic high of 36.7GtCO2 in 2019.

The researchers say they “were expecting some sort of rebound in 2021” as the global economy bounced back from Covid-19, but that it was “bigger than expected”.

While fossil emissions are expected to return to near-record levels, the study also reassesses historical emissions from land-use change, revealing that global CO2 output overall may have been effectively flat over the past decade.

The 2021 GCP almost halves the estimate of net emissions from land-use change over the past two years – and by an average of 25% over the past decade.

These changes come from an update to underlying land-use datasets that lower estimates of cropland expansion, particularly in tropical regions. Emissions from land-use change in the new GCP dataset have been decreasing by around 4% per year over the past decade, compared to an increase of 1.8% per year in the prior version. 

However, the GCP authors caution that uncertainties in land-use change emissions remain large and “this trend remains to be confirmed”.

The GCP study, which is not yet peer-reviewed, is the 16th annual “global carbon budget”. The budget also reveals:

• China and India both surpassed their 2019 emission peaks in 2021. Chinese emissions grew by 5.5% between 2019 and 2021, while Indian emissions grew by 4.4%. 
• Chinese coal use was a particularly large driver of the global rebound in emissions, with the power and industry sectors in China the main contributors. 
• Coal, oil and gas all fell during the pandemic, but both coal and gas emissions have already surpassed their pre-pandemic levels, with a 2% increase in gas emissions and a 1% increase in coal emissions between 2019 and 2021. 
• Oil emissions remain around 6% below 2019 levels and this persistent reduction is one of the main reasons 2021 emissions did not set a new record.

The new updates to global CO2 emissions in the GCP substantially revise scientists’ understanding of global emissions trajectories over the past decade. The new data shows that global CO2 emissions have been flat – if not slightly declining – over the past 10 years. 

However, falling land-use emissions have counterbalanced rising fossil CO2 emissions, and there is no guarantee these trends will continue in the future."