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Global energy-related carbon dioxide (CO2) emissions rose by 6% in 2021 to 36.3 billion tonnes, their highest ever level, as the world economy rebounded from the pandemic and relied heavily on coal to power that growth, according to new IEA analysis.
The increase in global CO2 emissions of over 2 billion tonnes was the largest in history in absolute terms, more than offsetting the previous year’s pandemic-induced decline, the IEA analysis shows.
The recovery of energy demand in 2021 was compounded by adverse weather and energy market conditions – notably the spikes in natural gas prices – which led to more coal being burned despite renewable power generation registering its largest ever growth.
The global CO2 emissions and energy demand numbers are based on the IEA’s detailed region-by-region and fuel-by-fuel analysis, drawing on the latest official national data and publicly available energy, economic and weather data. Combined with the methane emissions estimates that the IEA published last month and estimates of nitrous oxide and flaring-related CO2 emissions, the new analysis shows that overall greenhouse gas emissions from energy rose to their highest ever level in 2021.
Coal accounted for over 40% of the overall growth in global CO2 emissions in 2021, reaching an all-time high of 15.3 billion tonnes. CO2 emissions from natural gas rebounded well above their 2019 levels to 7.5 billion tonnes. At 10.7 billion tonnes, CO2 emissions from oil remained significantly below pre-pandemic levels because of the limited recovery in global transport activity in 2021, mainly in the aviation sector.
Despite the rebound in coal use, renewable energy sources and nuclear power provided a higher share of global electricity generation than coal in 2021. Renewables-based generation reached an all-time high, exceeding 8 000 terawatt-hours (TWh) in 2021, a record 500 TWh above its 2020 level. Output from wind and solar PV increased by 270 TWh and 170 TWh, respectively, while hydro generation declined due to the impacts of drought, notably in the United States and Brazil.
The use of coal for electricity generation in 2021 was intensified by record high natural gas prices. The costs of operating existing coal power plants across the US and many European power systems were considerably lower than those of gas power plants for the majority of 2021. Gas-to-coal switching pushed up global CO2 emissions from electricity generation by well over 100 million tonnes, notably in the US and Europe where competition between gas and coal power plants is tightest.