Global energy-related carbon dioxide (CO2) emissions rose less strongly in 2023 than the previous year even if total energy demand growth accelerated, a new International Energy Agency (IEA) analysis shows.

The lower emissions increase is attributed to the continued expansion of solar PV, wind, nuclear power and electric cars, which helped avoid greater use of fossil fuels.

Without clean energy technologies, the global increase in CO2 emissions in the last five years would have been three times larger, IEA said.

Emissions increased by 410 million tonnes, or 1.1%, in 2023 compared with a rise of 490 million tonnes the year before.

An exceptional shortfall in hydropower due to extreme droughts – in China, the United States and several other economies – resulted in over 40% of the rise in emissions in 2023 as countries turned largely to fossil fuel alternatives to plug the gap.

IEA added: "Had it not been for the unusually low hydropower output, global CO2 emissions from electricity generation would have declined last year, making the overall rise in energy-related emissions significantly smaller."

The new findings come from the IEA’s annual update on global energy-related CO2 emissions and the inaugural edition of a new series, the Clean Energy Market Monitor, which provides timely tracking of clean energy deployment for a select group of technologies and outlines the implications for global energy markets more broadly.

The report notes advanced economies witnessed a record fall in their CO2 emissions in 2023 despite growing GDPs.

"Their emissions dropped to a 50-year low while coal demand fell back to levels not seen since the early 1900s. The decline in advanced economies’ emissions was driven by a combination of strong renewables deployment, coal-to-gas switching, energy efficiency improvements and softer industrial production.

It is understood that  2023 was the first year in which at least half of electricity generation in advanced economies came from low-emissions sources like renewables and nuclear.

“The clean energy transition has undergone a series of stress tests in the last five years – and it has demonstrated its resilience,” said IEA executive director Fatih Birol. “A pandemic, an energy crisis and geopolitical instability all had the potential to derail efforts to build cleaner and more secure energy systems. Instead, we’ve seen the opposite in many economies."

From 2019 to 2023, growth in clean energy was twice as large as that of fossil fuels. The new IEA analysis shows that the deployment of clean energy technologies in the past five years has substantially limited increases in demand for fossil fuels, providing the opportunity to accelerate the transition away from them this decade.

IEA added that the deployment of wind and solar PV in electricity systems worldwide since 2019 has been sufficient to avoid an amount of annual coal consumption equivalent to that of India and Indonesia’s electricity sectors combined and to dent annual natural gas demand by an amount equivalent to Russia’s pre-war natural gas exports to the European Union.

The growing number of electric cars on the roads, accounting for one-in-five new car sales globally in 2023, also played a significant role in keeping oil demand – in terms of energy content – from rising above pre-pandemic levels, the report said.

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