Climate Research

2021 CO2 emissions at nearly 2019 level

Global Carbon Project presents new report on the development of the greenhouse gas
[04. November 2021] 

After dropping considerably worldwide in 2020, this year fossil carbon dioxide emissions will likely reach the level before the outbreak of the coronavirus pandemic. That’s the conclusion arrived at by the Global Carbon Project. Every year, experts assess how much CO2 was released into the atmosphere around the globe, and how much was absorbed by natural sinks. Dr Judith Hauck, a climate researcher at the Alfred Wegener Institute, is also part of the team. The project has just released its preliminary report in the journal Earth System Science Data.

Last year, the coronavirus pandemic also affected CO2 emissions. Measures taken to contain the virus impacted a number of relevant sectors like transport, industry and energy. As a result, global carbon dioxide emissions dropped by 5.4 percent on average in 2020. But the initial figures from the Global Carbon Project indicate that it wasn’t a lasting change: at 36.4 billion metric tons, the 2021 emissions will nearly reach the 2019 level, i.e., the level before the pandemic. That’s ca. 4.9 percent (4.1 percent to 5.7 percent) higher than in 2020.

This year, the emissions from coal and gas consumption are likely to increase more than they declined in 2020, although the emissions from burning oil will remain below the 2019 level.

Figures for the greatest CO2 emitters

In those countries that emit the most CO2, the 2021 emissions seem to be returning to the pre-pandemic trends, i.e., declining CO2 emissions in the United States and the European Union and rising emissions in India. In China, the response to the pandemic has led to a further rise in CO2 emissions, driven by the energy and industrial sectors.

  • EU27: In 2021, CO2 emissions will likely be 7.6 percent higher than in 2020 and reach 2.8 billion metric tons (7 percent of total global emissions). As such, emissions will be 4.2 percent below the 2019 level.
  • USA: In the United States, too, emissions will rise by 7.6 percent, to 5.1 billion metric tons (14 percent of total global emissions). That’s 3.7 percent below the 2019 level.
  • China: In 2021, emissions will rise by 4 percent to 11.1 billion metric tons (31 percent of total global emissions); 5.5 percent above the 2019 level.
  • India: CO2 emissions will most likely increase by 12.6 percent to 2.7 billion metric tons (7 percent of total global emissions). That’s 4.4 percent above the 2019 level.

In 2021, land-use-related activities will account for ca. 2.9 billion metric tons of CO2 emissions, slightly less than in 2020. In this regard, the CO2 emissions from e.g. deforestation and the absorption of CO2 in sustainable forests have been taken into account. CO2 emissions remained high throughout the pandemic, reaching 14.1 billion metric tons of CO2 per year for the decade 2011 to 2020. Together with CO2 absorption of nearly 9.9 billion metric tons per year by sustainable forests, in the course of the last decade a net value of 4.1 billion metric tons of CO2 per year were released into the atmosphere by land-use change.

For the first time, the Global Carbon Project combined independent data from global carbon models with the national greenhouse-gas inventories of the countries assessed. The data reported by the countries in question attributes part of the natural land-based sinks in agricultural areas to the land-use sector, while the models draw a clear distinction between natural and anthropogenic emissions.

Ocean and land as natural CO2 sinks

According to the preliminary report, the global percentage of CO2 that remains in the atmosphere will continue to rise this year, by 2.0 ppm to an estimated 415 ppm (parts per million). As expected, CO2 sinks on land and in the ocean are responding by absorbing more CO2 – all told, roughly half of all carbon dioxide emissions (54 percent on average over the past ten years). However, climate change is having deleterious effects on these reservoirs: model-based estimates indicate a 15 percent drop in effectiveness in land-based sinks and ca. 5 percent in the ocean.


Dr Judith Hauck is a climate researcher at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). For the Global Carbon Project, she coordinates the estimates of how much CO2 is stored by the ocean. “This year was the first time that we not only used models to simulate the ocean sinks, but also included observation-based estimates.” The preliminary findings: in the course of 2021, the ocean will absorb ca. 10.6 billion metric tons of CO2. This will continue the trend of increasing CO2 absorption in the ocean, running parallel to rising concentrations of atmospheric CO2. Over the past decade (2011 to 2020), they rose to 10.3 billion metric tons of CO2 per year on average, amounting to 26 percent of total CO2emissions. “The development of the ocean carbon sink over the next few decades, in response to rising CO2concentrations and worsening climate change alike, will also affect the atmosphere. How exactly it will do so is something we’re currently investigating at the AWI.”                

The natural land sink, which absorbed ca. 28 percent of anthropogenic emissions in the last decade, has increased its capacity over the past two decades. In the course of 2021, it will absorb an estimated 12.1 billion metric tons of CO2.

The remaining carbon budget is dwindling

Prolonged high emissions levels have further reduced the available carbon budget for limiting global warming to 1.5 degrees, 1.7 degrees or 2 degrees Celsius. As the Global Carbon Project reports, only 420 billion metric tons, 770 billion metric tons and 1,270 billion metric tons of CO2 remain for a 50-percent chance of achieving the 1.5-, 1.7- or 2-degree target, respectively. This equates to roughly 11, 20 or 32 years if emissions remain at the projected level for 2021. “The rebound in CO2 emissions to nearly the 2019 level shows that the countries’ plans still contain virtually no structurally effective solutions for a lasting reduction in emissions,” says Hauck. “The coronavirus lockdowns haven’t yet produced any lasting effect. Accordingly, we now need to find effective solutions and implement them globally in order to lastingly cut emissions.” After all, the goal of eliminating net greenhouse-gas emissions by 2050 (net-zero emissions) can only be reached if the total CO2 emissions are reduced by 1.4 billion metric tons on average every year. “In other words, we need to achieve the same kind of reduction that we saw in 2020, every year. That was a drop of 1.9 billion metric tons, mostly due to the lockdown-induced decline in mobility, but also in production.”

The Global Carbon Project is an international research project of Future Earth, a research initiative focusing on global sustainability. Its goal is to arrive at a comprehensive view of the carbon cycle, one that includes not only its bio-physical aspects, but also the human dimension and the interactions between them. Climate researchers from around the world contribute to the report. In Germany, experts from the Alfred Wegener Institute (Bremerhaven), Ludwig-Maximilians-Universität (Munich), Max Planck Institute for Meteorology (Hamburg), Max Planck Institute for Biogeochemistry (Jena), Karlsruhe Institute of Technology, GEOMAR Helmholtz Centre for Ocean Research (Kiel) and Leibniz Institute for Baltic Sea Research (Warnemünde) are participating.

The Global Carbon Budget 2021 is the 16th edition of the annual report. The numbers represent an update from 2020 which the IPCC used in the first part of its Sixth Assessment Report.

Additional information: 

Data and graphics:   

Data atlas

Webstory on the CO₂ budget, prepared by the Helmholtz climate initiative (in German):

Original publication

Friedlingstein et al. (2021) Global Carbon Budget 2021. Earth System Science Data (preprint). DOI: 10.18160/gcp-2021



Judith Hauck


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The Institute

The Alfred Wegener Institute pursues research in the polar regions and the oceans of mid and high latitudes. As one of the 18 centres of the Helmholtz Association it coordinates polar research in Germany and provides ships like the research icebreaker Polarstern and stations for the international scientific community.

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