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Global carbon dioxide (CO2) emission from cement and fossil fuels has rebounded by 4.6% this past year, new estimates suggest. This is following a Covid-related dip in 5.2% in 2020.
The Global Carbon Project(GCP) projects fossil emissions in 2021 to reach 36.4bn tons of CO2 (GtCO2), just 0.8% less than their pre-pandemic high (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 return to near record levels, the study also reassesses historical land-use change emissions, revealing that global carbon dioxide output may have been flat in 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 are due to an update of the underlying land-use data. They have lower estimates for cropland expansion, especially in tropical regions. The GCP dataset has seen emissions from land-use change decrease by approximately 4% per annum over the past decade, as opposed to the 1.8% increase in the previous 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The GCP study, which is not yet peer-reviewed, is the 16th annual “global carbon budget”.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 contains:
- Both India and China both exceeded their 2019 emission peaks by 2021. Between 2019 and 2021 Chinese emissions increased by 5.5% while Indian emissions grew 4.4%
- The global rebound in emissions was driven in large part by Chinese coal use. The main contributors to this were the power and industrial sectors of China.
- Oil, coal, and gas all fell during pandemic. However, both coal and gas emissions have already exceeded their pre-pandemic levels with a 2% rise in gas emissions and an increase of 1% in coal emissions between 2019-2021.
- Oil emissions are still below 2019 levels by 6%. This persistent reduction is one reason 2021 emissions didn’t 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 offset rising fossil CO2 emission, and it is uncertain if these trends will continue.
Major changes caused by revised land-use emissions
The GCP has reported on both land-use change (LUC) and fossil CO2 emissions. Fossil CO2 emissions represent upwards of 90% of current global emissions and understandably tend to get most of the attention. However, GCP researchers long ago pointed out that LUC has the largest uncertainties in understanding CO2 emission, despite being a small part of the total.
Below is a graphic showing global CO2 emissions from fossil and LUC sources. The dashed line in light blue represents the previous GCP estimate of global carbon dioxide emissions. The solid blue is the new estimate. The new GCP estimate includes both land use uncertainty and fossil CO2 emissions.
Annual total global CO2 emissions – from fossil and land-use change – between 2000 and 2021 for both the 2020 and 2021 versions of the Global Carbon Project’s Global Carbon Budget. The budget for 2021 is shaded in the shaded area. Data from the Global Carbon Project; chart using Carbon Brief Highcharts.
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. If 2020 and 2021 are added, the new GCP dataset actually shows slightly decreasing global CO2 emissions over the past decade. However, this should still be considered cautiously due to the temporary nature Covid-related decreases.
The GCP dataset also shows historical (1750-2020), cumulative emissions around 19 GtCO2 lower in the 2020 version than in the previous 2020 version. This is roughly equivalent to half a calendar year of current global emissions.
This would be a slight (4% or half-a-year of current emissions) rise in the remaining “carbon budget”Around 460GtCO2 (which is 11.5 Years of current emissions) will be required to limit warming to 1.5C by 2021, with a 50% chance.
The historical global fossil emissions are mostly unchanged from their previous values in the GCP data. There are some minor upwards revisions of fossil CO2 emissions of around 0.3 GtCO2 for most years over the past decade – and a somewhat larger upward revision of 0.7 GtCO2 for the year 2020.
Revisions in land-use emissions are almost entirely responsible for the recent global CO2 emission reductions. Below is a graph showing land-use emissions in the previous 2020 GCP data (dark blue solid lines) and the new 2021 data. There are also reported uncertainties.
Annual global CO2 emissions from land-use change between 1959 and 2021 for both the 2020 and 2021 versions of the Global Carbon Project’s Global Carbon Budget. The budget for 2021 is shaded in the shaded area. Data taken from the Global Carbon Project; chart using Carbon Brief Highcharts.
Although there have been some minor changes to LUC emissions estimates since 1999, more substantial changes have been observed over the past 20 decades. The previous report showed that LUC emissions had increased by about a third between 2000 and 2020.
The new data almost reverses this trend and suggests that LUC emission have actually decreased by around a quarter of a percent since 2000. LUC emissions have been decreasing by 4% per annum over the past decade, from increasing by 1.8%/year in the most recent version of the GCP data.
GCP uses the average of three different observational-based land-use change datasets? known as “H&N”, “BLUE” and ”OSCAR”. In the prior year’s GCP report these three approaches showed notable disagreements over the past decade, with H&N showing emissions declines, while BLUE and OSCAR showed emissions increases. However, revisions to both BLUE and OSCAR datasets in the past year have brought them more in-line with recent H&N trends.
All three datasets now show notable declines in emissions over the past decade – though differences remain in the magnitude of estimates between H&N and the other two datasets, as shown in the figure below.
Annual global CO2 emissions from land-use change between 1959 and 2021 for the three bookkeeping methods used by the Global Carbon Project – H&N, BLUE, OSCAR – for both 2020 and 2021 versions. Data from the Global Carbon Project; chart using Carbon Brief Highcharts.
Notable is the fact that all three datasets agree now on the declines of emissions. The GCP paper suggests that “there is a decrease in net CO2 emissions from land-use change over the last decade, in contrast to earlier estimates of no clear trend across LUC estimates”.
These revisions are primarily due changes in the underlying land-use data. History database of the Global Environment(HYDE). HYDE now uses satellite-based updated estimates of agricultural areas, and land cover maps. This allows for lower cropland expansion estimates, especially in tropical regions. The updated data removes spurious interannual variability that could have caused an increase in emissions due to assumed rapid decay (e.g. clearing by fire) and slower growth.
However, the authors warn that the new estimates may not capture the increase in Brazilian deforestation over the past few years. It does not include forest degradation – deterioration of forest ecosystems that does not involve a reduction in forested area – that may be contributing to some additional LUC emissions.
As Prof Julia Pongratz – the director of the Department of Geography at the Ludwig Maximilian University of Munich and a member of the GCP team – explains to Carbon Brief:
“It is too early to infer robust trends. More regional analysis and high-resolution monitoring are needed to understand land-use dynamics. Only then can we reduce the uncertainty around land-use emissions and their trends and their contributions to emissions reduction targets.”
China and India lead rapid growth in fossil CO2 emissions
Global fossil CO2 emissions plummeted rapidly during the peak of the Covid-19 pandemic, 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. China and India are leading the rebound in global emissions. They have already surpassed their previous record highs for 2019!
Participating in a media briefing Dr Glen Peters – research director at the Center for International Climate Research (CICERO) – said the researchers “were expecting some sort of rebound in 2021”, but that it was “bigger than expected”. He added:
“You could say the recovery packages have delivered more in emissions than we were hoping – a little bit too dirty in the recovery packages and not enough low-carbon expenditure.”
Prof Corinne Le Quéré – Royal Society research professor of climate change science at the University of East Anglia – noted that the decrease in emissions in 2020 was not a “structural decrease”. She explained:
“It is the difference between parking your car for a year and changing to an electric car. [The decline in emissions]It was not [because of]Climate change adaptation measures [so] they were never going to last.”
The following figure shows global CO2 emission from fossil fuels. It is broken down into emissions from China (red shading), India, the US (bright), EU (dark), and the rest (grey).
Annual fossil CO2 emission by major country and rest world from 1959-2021, measured in billions to tonnes of CO2 annually (GtCO2). The 2021 numbers shown are preliminary estimates. Data taken from the Global Carbon Project; chart using Carbon Brief Highcharts.
After a rapid increase of global fossil CO2 emissions by about 3% per year from 2001 to 2010, emissions only increased by approximately 1% per year between 2011-2019. The onset of Covid-19 – and early predictions of a potential long global economic slowdown – led to some discussion about global emissions potentially having peaked2019
However, the recovery of global emissions in 2021 was much faster and more intensive than expected. For example, the IEA’s 2020 World Energy Outlook(WEO), projected that global emission levels would not exceed 2019 levels until near 2030. Recent 2021 WEOProjections show that global emissions will rebound beyond 2019 levels by 2022 and 2023.
While global emissions – and those of most countries – will remain below 2019 levels in 2021, both China and India stand out among major emitters as having notably larger emissions despite the pandemic. The following graph shows the change in global emissions as well as in major emitting regions and countries between 2019-2021 (yellow bar), 2020-2021 and 2021 (blue bars), and 2019-2021 (2021-2021) (red bars).
The percentage change in CO2 between 2019-2020, 2021, 2021, and 2021, as well as between 2019-2021 for the entire world and major emitting countries/regions. Data from the Global Carbon Project; chart using Carbon Brief Highcharts.
China is the only major emitting nation to have increased its emissions in 2020. This is due to the relatively small impact of Covid-19 upon its economy. The largest contributor to global emissions rebound was China’s 1.7% increase in emissions between 2019-2021 and 5.5% between 2019-2021.
As the GCP points out: “The global growth in fossil CO2 emissions mainly arises from the growth in coal use in the power and industry sectors in China.”
India’s emissions fell by 7% in 2020, but grew by 12% in 2021 for an overall increase in emissions of 4.4% between 2019 and 2021. Although the percentage increase in Indian emissions between 2019-2021 is similar to China’s, it doesn’t take into account the fact that China’s actual emissions increased by approximately five times.
Emissions in contrast fall by 10% in the US, 11% for the EU and 7% for the rest of the globe between 2019 and 2020. They are still 3.7% lower than 2019 levels in the US, 4.2% less in the EU, and 4.2% less in the rest the world in 2021.
Below is a list of the total emissions for each year from 2018 to 2021 as well as the countries responsible for these changes. The black bars show the annual emissions for 2018, 2020, and 2021 estimates. The coloured bars represent the change in emissions from one year to another, broken down according to country. Negative values signify a decrease in emissions, while the positive value indicates an increase in emission.
Black bars indicate annual global CO2 emission from fossil fuels. Coloured bars indicate drivers of changes between years and countries. Negative values signify a reduction in emissions. It is important to note that the y axis does not begin at zero. Data from the Global Carbon Project; chart using Carbon Brief Highcharts.
Globally, fossil CO2 emissions will rise by 4.6% in 2021. Many countries and regions are contributing to the recovery of emissions from the 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.
Despite fossil CO2 emissions continuing to rise, global average per capita fossil emissions have remained flat over 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. The following figure shows the global average emissions per capita for each year 1959 to 2021 for both total and fossil CO2 (orange).
Global per-capita carbon dioxide emissions from fossil CO2 (orange), as well as total CO2 emissions (blue), between 1959-2021, in tonnes CO2 per individual. These numbers are only estimates. Data from the Global Carbon Project; chart using Carbon Brief Highcharts.
Continued growth in gas and a strong rebound in coal use
Global fossil fuel emissions are primarily caused by the combustion of coal and oil. About 41% of global fossil CO2 emissions are caused by coal, which is the most important fossil fuel. Petroleum is the second largest contributor with 32% of fossil CO2, followed by oil at 21%.
These percentages reflect not only the global consumption of each fossil fuel, but also the differences in CO2 intensities. After oil and natural gases, coal emits the most CO2 per unit heat or energy produced.
Last year saw declines from all three fuels. The largest drops were in oil emissions (down nearly 5%), as transportation use was severely curtailed during the peak of the pandemic. In 2020, coal use was down 4% and gas use a modest 2%. Both coal and oil have experienced a rebound in 2021. They both saw their emissions rise by more than 5%.
GCP projects that 2021 will have 2% more gas emissions than in 2019. This is compared to the pre-pandemic levels of 2019 emissions. Due to lingering changes in transportation use, oil emissions will likely remain at 6% or less than 2019.
Below is a chart that shows the total emissions for each year from 2018 to 2021 as well as the fuels responsible for the change in emission.
Black bars show annual global CO2 emissions from fossil-fuels and drivers of changes between fuel years (coloured bars). Negative values signify a reduction in emissions. It is important to note that the y axis does not begin at zero. Data taken from the Global Carbon Project; chart using Carbon Brief Highcharts.
GCP authors warn that global coal use is likely to continue growing and exceed its 2014 peak due to its current rapid growth. Despite recent progress in limiting the financing of new coal plant, this is because most of the growth in coal capacity over the next few years will be driven by domestic Indian or Chinese plants.
Below is a graph showing the evolution of global CO2 emissions over time from different fuels. While coal emissions rose rapidly in the mid-2000s it has remained steady since 2013. However, oil and gas emissions have grown steadily since the pandemic.
Annual CO2 emissions from fossil fuels between 1959-2021, in billions to tonnes of CO2 per annum (GtCO2). The 2021 numbers shown are preliminary estimates. Data from the Global Carbon Project; chart using Carbon Brief Highcharts.
GCP authors warn that global coal use is likely to continue growing and exceed its 2014 peak due to its current rapid growth. Despite recent progress in limiting the financing of new coal plant, this is because most of the growth in coal capacity over the next few years will be driven by domestic Indian or Chinese plants.
Below is a graph showing the evolution of global CO2 emissions over time from different fuels. While coal emissions rose rapidly in the mid-2000s it has remained steady since 2013. However, oil and gas emissions have grown steadily since the pandemic.
Changes in CO2 sources and sinks
The GCP gives an annual estimate of the global carbon budget. This is based on estimates for the CO2 released through human activity and its absorption by the oceans, land, and seas. The remainder adds to the atmospheric concentrations.
(This differs from the commonly used term “carbon budget”, referring to the amount of CO2 that can be released while keeping warming below global limits of 1.5 or 2C.)
The figure below shows the most recent budget. It also includes estimated values for 2021. Values above zero represent sources of CO2 – from fossil fuels, cement and land use – while values below zero represent “carbon sinks” that remove CO2 from the atmosphere. CO2 emissions can either accumulate in the atmosphere or are absorbed into the oceans and land vegetation.
From 1959-2021, the annual global carbon budget of sinks and sources. Due to uncertainties remaining, especially in sinks, the budget doesn’t always balance completely. 2021 numbers are estimates only. Data from the Global Carbon Project; chart using Carbon Brief Highcharts.
The atmospheric CO2 concentration increased by 2.4 parts/million (ppm), and is expected to increase by approximately 2ppm by 2021. This would result in atmospheric concentrations at 415ppm, on average, for the year. Around 47% of total carbon dioxide emissions have remained in atmosphere over the past decade. The remainder has been absorbed by ocean and land sinks.
GCP estimates that the increase in atmospheric CO2 due to pandemic-related emission reductions in 2020 was 0.18ppm less than in the absence pandemic. The GCP estimates that 2021 will see a lower atmospheric CO2 concentration. La NiñaConditions that enhance the land carbon sequester
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