CO2 emissions in 2021 set to rebound to 2019 levels

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Although global average carbon dioxide emissions from fossil fuel combustion dipped sharply in 2020, the current year has seen them rebound almost to their pre-pandemic levels. This is one finding of the Global Carbon Project, in which LMU geographer Julia Pongratz plays a key role. Each year, scientists calculate how much CO₂ is given off into the atmosphere worldwide and how much is reabsorbed by natural sinks.

Last year, the coronavirus pandemic affected not just public health: Measures to contain the virus also affected CO₂ emissions from many sectors, such as transport, industry and energy. The world’s carbon dioxide emissions thus dropped by 5.4 percent on average in 2020. The effect did not last long, however – witness the preliminary figures in the latest Global Carbon Project report: At 36.4 billion tons, emissions in 2021 are close to the pre-pandemic levels recorded in 2019. This figure equates to a roughly 4.9 percent increase (between 4.1 percent and 5.7 percent) compared to 2020. Emissions from the consumption of coal and gas rose faster in 2021 than they fell in 2020, while emissions from the combustion of oil remained lower than in 2019.

The biggest producers of CO2

For the major emitting countries, fossil emissions in 2021 seem to have reverted to pre-pandemic trends, declining in the United States and the European Union but increasing in India. China’s response to the coronavirus pandemic led to a further rise in CO₂ emissions that was driven by the power and industry sectors.

• EU27: CO₂ emissions for the whole of 2021 are likely to be 7.6 percent higher than in 2020 at 2.8 billion tons (7 percent of the global total). This figure is 4.2 percent below 2019 levels.
• USA: At 5.1 billion tons (14 percent of the global total), emissions in the United States are likewise up by 7.6 percent 2021 compared to 2020, but 3.7 percent lower than in 2019.
• China: 2021 emissions will be 4.0 percent higher than a year ago at 11.1 billion tons (31% of the global total), equating to a 5.5 reduction relative to 2019.
• Indien: The subcontinent’s CO₂ emissions will probably climb 12.6 percent to 2.7 billion tons this year (7 percent of the global total), reflecting a 4.4 percent drop compared to 2019.

Julia Pongratz coordinates the Global Carbon Project's assessment of emissions from land use change, which stands at around 2.9 billion tons of net CO₂ in 2021. Compared to the previous year’s estimate of 3.2 billion tonnes of CO₂, the trend is downward but very uncertain. This comparatively small net flux includes substantial gross emissions from deforestation in particular, as well as CO₂ removal, for example from afforestation and reforestation after wood harvest. In the decade from 2011 through 2020, annual gross CO₂ emissions totaled 14.1 billion tons. “Yet these emissions would drop quickly and sharply if a moratorium on deforestation like the one resolved in Glasgow were implemented,” says LMU geographer Clemens Schwingshackl, who also took part in the study. However, the scientist suspects that the effects of the pandemic probably point in the opposite direction: In several countries, restrictions on the monitoring and legal enforcement of measures to counter tropical deforestation have been observed in the wake of lockdowns and limited budgets.

For the first time, the Global Carbon Project this year linked independent data from global carbon cycle models to the national greenhouse gas inventories reported by countries. While the models distinguish between natural and anthropogenic processes, the data reported by the countries assigns parts of the natural land sinks to the land use sector, when they occur on managed land (counted towards natural processes in the global model's approach). Across countries, the land-use sector thus constitutes a global CO₂ sink. If the different ways of attributing the natural sinks is accounted for, the two approaches are consistent. “Linking the independent estimates of the global carbon cycle models to the national greenhouse gas inventories is an important step in view of the Global Stocktake, with which the implementation of the Paris Agreement and the common progress towards the agreed goals can be evaluated,” Pongratz says.

Oceans and land as natural carbon sinks

According to the preliminary report, the global share of CO₂ that remains in the atmosphere is continuing to increase this year, rising by 2.0 parts per million (ppm, the unit used to measure the composition of gases) to what is likely to be 415 ppm. Carbon sinks on land and in the oceans are responding to this gain as expected and absorbing more CO₂. Between them, they capture about half of carbon dioxide emissions (a mean of 54 percent over the past ten years).

That said, climate change is causing them to suffer: Modeled assessments show that climate change is weakening carbon sinks by around 15 percent on land and some 5 percent in the oceans. “The forests, which are so important as natural carbon sinks, are under especially severe pressure,” Pongratz adds. “We saw that again in this summer’s fires in Siberia, on the US West coast and around the Mediterranean.”

A shrinking carbon budget

Persistently high emissions have further narrowed the carbon budget with which global warming might still be kept below 1.5, 1.7 or 2 degrees Celsius. The Global Carbon Project report indicates that we still have around 420 billion tons of CO₂ if we want to stay below a 1.5-degree rise, 770 billion tons to keep to a 1.7-degree trajectory or 1,270 billion tons to at least avoid exceeding the 2-degree target. These numbers translate into periods of around 11, 20 or 32 years respectively if emissions stay as high as in 2021.

The Global Carbon Project is an international research project run by the Future Earth research initiative on global sustainability. Its goal is to develop a complete picture of the global carbon cycle, including both its biophysical and human dimensions together with interactions and feedbacks between them. Climate researchers from around the world collaborate on the report. Germany is represented by scientists from the Alfred Wegener Institute (Bremerhaven), LMU (Munich), the Max Planck Institute for Meteorology (Hamburg), the Max Planck Institute for Biogeochemistry (Jena), the Karlsruhe Institute of Technology, the GEOMAR Helmholtz Center for Ocean Research (Kiel) and the Leibniz Institute for Baltic Sea Research (Warnemünde).

The Global Carbon Budget 2021 is the project’s 16th yearly report. Its numbers were updated in 2020 and were incorporated in the first part of the Sixth Assessment Report published by the Intergovernmental Panel on Climate Change (IPCC).

At COP26 in Glasgow, the Global Carbon Budget will be presented in the IPCC Science Pavilion at 10:30 am (CET) on November 4. Watch the VOD on YouTube..

Publication: Friedlingstein et al. (2021) Global Carbon Budget 2021. Earth System Science Data (preprint).

Global Carbon Project:Data and charts