Faster global warming linked to Chinese aerosol cuts

[NEW DELHI, SciDev.Net] Chinese air quality improvements are likely to have contributed to accelerated global surface temperature warming, according to a research paper, with the Asian landmass warming at twice the global average.

The study, published this month in Nature Communications, Earth and Environment, says East Asian efforts to reduce atmospheric aerosols was likely to have accelerated global surface warming since around 2010.

The researchers say policies to reduce air pollution implemented by East Asian countries, particularly China, have led to a 75 per cent decrease in sulfate aerosol emissions in that time.

Bjørn H. Samset, lead author and senior researcher at CICERO Centre for International Climate Research, said this “has likely driven much of the recent global warming acceleration, and also warming trends in the Pacific”.

Global surface warming has accelerated since 2010, compared to the preceding 50 years, according to the Nature study.

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Jayanarayanan Kuttippurath, associate professor at the Centre for Ocean, River, Atmosphere and Land Sciences, at the Indian Institute of Technology, Kharagpur, explains that efforts to reduce aerosol pollutants can facilitate more radiation at the Earth’s surface and this can result in warming.

However, Kuttippurath, who was not involved in the study, also added that it was tricky to accurately forecast the effect of aerosol reductions on atmospheric processes.

“Cloud-aerosol interaction is important but difficult to accurately simulate for study purposes,” he said.

“At my centre, we are already working on finding out the impact of aerial pollution reduction in the Asia-Pacific.”

The researchers behind the Nature study say the findings show that the acceleration of warming due to reductions in air pollution is likely to be short-lived.

However, for many communities the impacts of climate change are happening now.

Heatwaves and cyclones

Roxy Mathew Koll, a scientist at the Indian Institute of Tropical Meteorology, Pune, tells SciDev.Net that until around 2000, warming over Asia — especially the Indian subcontinent — was relatively modest compared to other regions. But over the past two to three decades, temperatures have risen sharply.

“This acceleration is already intensifying heatwaves, disrupting monsoons, fueling cyclones, raising sea levels, and melting glaciers,” said Koll.

“Asia’s cities, coastlines, and food systems are on the frontlines of this unfolding crisis.”

It comes after the State of the Climate in Asia 2024 report, published in June by the World Meteorological Organization (WMO), said Asia is warming twice as fast as the global average, driving extreme weather events and putting lives at risk.

The WMO report said Asia was warming more rapidly because of its large landmass, as temperatures over land increase more quickly than those over sea.

“Variations in surface temperature have a large impact on natural systems and on human beings,” the report said.

The oceans around Asia are also experiencing temperature increases with surface temperatures in the Indian and Pacific Oceans reaching record levels in 2024.

Albert Salamanca, senior research fellow and head of secretariat at the Adaptation Research Alliance, the Stockholm Environment Institute, told SciDev.Net: “Climate change is no longer a distant threat but a tangible reality with profound impacts on people in Asia — and the rest of the global South.”

Salamanca says the WMO report reinforces the need to step up emissions reductions to ensure that the internationally agreed thresholds of 1.5 degrees and 2 degrees Celsius above pre-industrial levels are not exceeded – and to support countries most impacted to adapt.

“We need countries responsible for historical emissions and those driving current emissions to do far more to reduce global greenhouse gas levels,” he said.

“Wealthy developed countries that have benefited from historical emissions must provide resources to support those who suffer the most but have contributed the least — not out of charity, but out of responsibility and solidarity.”

US$800 billion shortfall

According to an International Monetary Fund paper, emerging and developing Asia needs at least US$1.1 trillion annually for climate mitigation and adaptation — but investment falls short by US$800 billion.

At the UN climate conference COP29, in Baku, Azerbaijan, in November, wealthy countries committed to help raise US$300 billion a year by 2035 for climate action in low- and middle-income countries – a pledge considered inadequate by many climate-vulnerable countries.

The withdrawal of the US from the 2015 Paris Agreement and scrapping of the US International Climate Finance Plan adds to concerns over the progress of climate action.

Analysis by UK-based Carbon Brief says that nearly a tenth of global climate finance could disappear as a result of the Trump administration’s cuts.

In March, the US also announced withdrawal from the Just Energy Transition Partnerships, a financing mechanism to support coal-dependent countries transition to clean energy.

The withdrawal impacts over US$3 billion of US commitments in Vietnam and Indonesia — both industrialising nations aiming for net-zero emissions by 2050.

This piece was produced by SciDev.Net’s Asia Pacific desk.