According to the report, an increase in coal use was the principal factor driving up the world’s energy-related CO₂ emissions by over 2bn tonnes, the largest ever annual rise in absolute terms. This more than offset the pandemic-reduced decline in emissions during 2020, says the IEA. Influences such as spikes in natural gas prices and adverse weather conditions caused more coal to be burned, despite renewable power generation registering its greatest ever growth.

The IEA’s global CO₂ and energy demand figures come from region-by-region and fuel-by-fuel analysis. In combination with methane, nitrous oxide (NO_x) and flaring-related CO₂ emissions estimates, the IEA’s new analysis reveals that greenhouse gas emissions from energy reached their pinnacle level in 2021. 

Coal was responsible for over 40% of the overall growth in global emissions in 2021, forcing levels up to an all-time high of 15.3bn tonnes. Likewise, carbon emissions from burning natural gas also rebounded significantly higher than their 2019 levels, to 7.5bn tonnes. Of the fossil fuels, the agency’s analysis shows that only oil emissions remained below pre-pandemic levels – due to a limited recovery in global transport activity, particularly in the aviation sector.

Record-breaking natural gas prices led to gas-to-coal switching to generate electricity across Europe and the US. This boosted global CO₂ emissions from electricity generation by over 100mn tonnes. 

However, the greatest rebound came from China, where emissions increased by 750mn tonnes between 2019 and 2021. China was the only major economy to enjoy economic growth through both 2020 and 2021. Its emissions rise during this period more than offset the aggregate decline across the rest of the entire world. In 2021 alone, China’s CO₂ emissions grew to above 11.9bn tonnes, accounting for 33% of the globe’s total.

China’s spiralling emissions were mainly due to a 10% increase in electricity demand. Although the country was also seeing its greatest ever increase in renewable power output in 2021, demand outstripped supply and coal was employed to meet more than half of the rise in electricity demand. 

Likewise, India witnessed a strong rebound in CO₂ emissions in 2021, which rose above 2019 levels thanks to a growth in coal use for electricity generation. Coal-fired generation leapt 13% above its 2020 level, reaching an all-time high. In part this was because renewable energy growth declined to one-third of the average rate experienced over the previous five years.

Regardless of coal’s rebound in 2021, renewable energy sources and nuclear power still supplied a higher proportion of global electricity generation than coal. Renewables achieved an all-time high, exceeding 8,000 TWh in 2021, a record 500 TWh above the 2020 level. Solar PV and wind grew by 170 TWh and 270 TWh respectively, although hydro generation declined due to drought, particularly in the US and Brazil. 

Encouragingly, the IEA report finds that CO₂ emissions rebounded less sharply than global economic output in advanced economies, suggesting a long-term trajectory of decline. In the US, emissions in 2021 were 4% below 2019 levels; in the EU they were 2.4% lower; in Japan emissions fell by 3.7% in 2020 and rebounded by less than 1% in 2021. 

The report reminds the world to ensure that the global surge in emissions in 2021 is a one-off and to concentrate on accelerating the energy transition to improve global energy security and reduce energy prices for consumers.