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Soy plantation in Amazon rain forest, Brazil
Sojaplantagen im Amazonas Regenwald, Brasilien. Credit: Brazil Photos / Alamy Stock Photo.
November 4, 2021 0:01

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

Global carbon dioxide (CO2) emissions from fossil fuels and cement have rebounded by 4.9% this year, new estimates suggest, following a Covid-related dip of 5.4% in 2020.

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 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.

Major changes due to revised land-use emissions

The GCP has always reported on emissions from both fossil CO2 and from land-use change (LUC). Fossil CO2 emissions represent upwards of 90% of current global emissions and understandably tend to get most of the attention. However, the GCP researchers have long pointed out that the largest uncertainties in understanding of CO2 emissions comes from LUC, despite its relatively small contribution to the total.

Previously, the GCP data showed global CO2 emissions increasing by an average of 1.4 GtCO2 per year between 2011 and 2019 – prior to Covid-related emissions declines. The new revised dataset shows that global CO2 emissions were essentially flat – increasing by only 0.1GtCO2 per year from 2011 and 2019. When 2020 and 2021 are included, the new GCP data actually shows slightly declining global emissions over the past decade, though this should be treated with caution due to the temporary nature of Covid-related declines.

Global fossil CO2 emissions declined rapidly during the height of the Covid-19 pandemic in 2020. While there were hopes that a “green recovery” could help keep emissions down, the world has seen a rapid rebound in fossil CO2 emissions in 2021 as the global economy has recovered.

However, the recovery in global emissions in 2021 has been notably faster and more emissions-intensive than forecasted last year. For example, the IEA’s 2020 World Energy Outlook (WEO) projected that global emissions would not surpass 2019 levels until nearly 2030; by contrast, the recent 2021 WEO projects that global emissions will rebound past 2019 levels by 2022 or 2023.

Overall, fossil CO2 emissions are expected to rise by around 4.9% in 2021 with many countries/regions contributing to the recovery in emissions from 2020 lows. Global emissions will almost fully rebound, remaining only around 0.8% below 2019’s record levels, and putting the world on track to likely set a new record for fossil CO2 emissions in 2022.

Although fossil CO2 emissions have continued to increase, global average per-capita fossil emissions have been flat for the past decade. Per-capita total global emissions have been flat for much longer – since at least 1959 – though these numbers obscure large variations between countries.

Update: This article was updated on 04/11/2021 to amend the quoted rebound in fossil CO2 emissions in 2021 (4.9%, rather than 4.6%) and the dip in 2020 (5.4% rather than 5.2%), along with some of the country-specific numbers. The original figures, calculated by Carbon Brief, referred to annual emissions, while the GCP figures (which the article now quotes) is calculated based on average daily emissions. The two methods only differ because 2020 was a leap year and so has an extra day.