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The great climate paradox: Drop in air pollution has INCREASED global warming by making clouds less reflective, scientists warn READ MORE: Scientists say geoengineering could make climate change WORSE By SHIVALI BEST, SCIENCE & TECHNOLOGY EDITOR Published: 12:45 GMT, 5 November 2025 | Updated: 12:45 GMT, 5 November 2025 Scientists have been faced with a huge dilemma, as research reveals that reducing air pollution has increased global warming. While smog kills millions of people every year, it also whitens clouds – making them more reflective. So by slashing air pollution, we're inadvertently diminishing the brightness of clouds, which are key regulators of global temperature. In their new study, researchers from the University of Washington analysed the clouds over the Northeastern Pacific and Atlantic oceans between 2003 and 2022. Their analysis revealed that the clouds have become nearly three per cent less reflective per decade. And according to the experts, approximately 70 per cent of this change can be attributed to reductions in air pollution. 'When you cut pollution, you're losing reflectivity and warming the system by allowing more solar radiation, or sunlight, to reach Earth,' explained lead author Knut von Salzen. 'We may be underestimating warming trends because this connection is stronger than we knew. 'I think this increases the pressure on everyone to rethink climate mitigation and adaptation because warming is progressing faster than expected.' In their new study, researchers from the University of Washington analysed the clouds over the Northeastern Pacific and Atlantic oceans between 2003 and 2022. Their analysis revealed that the clouds have become nearly three per cent less reflective per decade While smog kills millions of people every year, it also whitens clouds – making them more reflective. So by slashing air pollution, we're inadvertently diminishing the brightness of clouds, which are key regulators of global temperature With global warming accelerating faster than ever, scientists around the world have been scrambling to understand the factors contributing to this increase. In their new study, the team focused on the impact of air pollution. Most previous studies have focused on the benefits of reducing smog. For example, a study published in May found that up to 250,000 deaths from poor air quality could be prevented annually in central and western Europe by 2050 if emissions are drastically reduced. As a result, there have been global efforts to limit pollution, with a gradual transition from oil and gas to clean energy. However, the new study, published in Nature Communications, shows that this reduction has had a surprising effect. 'Reductions in particulate air pollutants are contributing to accelerated warming,' said Sarah Doherty, a principal research scientist at the University of Washington. For the study, the team analysed 20 years of satellite data, documenting cloud dynamics above the Northeastern Pacific and Atlantic oceans – which are warming faster than almost anywhere else on Earth. Their analysis revealed that air pollution influences clouds in two ways. Firstly, small particles give water droplets something to cling to – and with a fixed amount of water, more aerosols means more small, reflective droplets in the clouds. By the same logic, reducing aerosols increases cloud droplet size, according to the researchers. Secondly, large droplets are heavier, and quicker to fall to Earth as precipitation, which decreases cloud cover. Given the detrimental impact of air pollution on human health, the solution is clearly not to increase air pollution. Instead, the researchers say there are several interventions we could consider that aim to make the clouds shinier without polluting the air. This includes 'marine cloud brightening' – a technique that involves spraying seawater into the air to make clouds more reflective. Dimming the sun isn't a bright idea: Controversial technique could wreak havoc on weather 'You could think of it as replacing unhealthy pollutant particles with another type of particle that is not a pollutant—but that still provides a beneficial cooling effect,' explained Robert Wood, a professor of atmospheric and climate science at the University of Washington. However, before these methods can be implemented, more research is need to check they're safe – and don't have any unintended consequences. For example, in a recent study, scientists from New York University warned that marine cloud brightening could wreak havoc on the weather, and even make climate change worse. Revealed: MailOnline dissects the impact greenhouse gases have on the planet - and what is being done to stop air pollution Carbon dioxide Carbon dioxide (CO2) is one of the biggest contributors to global warming. After the gas is released into the atmosphere it stays there, making it difficult for heat to escape - and warming up the planet in the process. It is primarily released from burning fossil fuels such as coal, oil and gas, as well as cement production. The average monthly concentration of CO2 in the Earth's atmosphere, as of April 2019, is 413 parts per million (ppm). Before the Industrial Revolution, the concentration was just 280 ppm. CO2 concentration has fluctuated over the last 800,000 years between 180 to 280ppm, but has been vastly accelerated by pollution caused by humans. AirVisual Privacy Policy Nitrogen dioxide The gas nitrogen dioxide (NO2) comes from burning fossil fuels, car exhaust emissions and the use of nitrogen-based fertilisers used in agriculture. Although there is far less NO2 in the atmosphere than CO2, it is between 200 and 300 times more effective at trapping heat. Sulfur dioxide Sulfur dioxide (SO2) also primarily comes from fossil fuel burning, but can also be released from car exhausts. SO2 can react with water, oxygen and other chemicals in the atmosphere to cause acid rain. Carbon monoxide Carbon monoxide (CO) is an indirect greenhouse gas as it reacts with hydroxyl radicals, removing them. Hydroxyl radicals reduce the lifetime of carbon dioxide and other greenhouse gases. Particulates What is particulate matter? Particulate matter refers to tiny parts of solids or liquid materials in the air. Some are visible, such as dust, whereas others cannot be seen by the naked eye. Materials such as metals, microplastics, soil and chemicals can be in particulate matter. Particulate matter (or PM) is described in micrometres. The two main ones mentioned in reports and studies are PM10 (less than 10 micrometres) and PM2.5 (less than 2.5 micrometres). Air pollution comes from burning fossil fuels, cars, cement making and agriculture Scientists measure the rate of particulates in the air by cubic metre. Particulate matter is sent into the air by a number of processes including burning fossil fuels, driving cars and steel making. Why are particulates dangerous? Particulates are dangerous because those less than 10 micrometres in diameter can get deep into your lungs, or even pass into your bloodstream. Particulates are found in higher concentrations in urban areas, particularly along main roads. Health impact What sort of health problems can pollution cause? According to the World Health Organization, a third of deaths from stroke, lung cancer and heart disease can be linked to air pollution. Some of the effects of air pollution on the body are not understood, but pollution may increase inflammation which narrows the arteries leading to heart attacks or strokes. As well as this, almost one in 10 lung cancer cases in the UK are caused by air pollution. Particulates find their way into the lungs and get lodged there, causing inflammation and damage. As well as this, some chemicals in particulates that make their way into the body can cause cancer. Deaths from pollution Around seven million people die prematurely because of air pollution every year. Pollution can cause a number of issues including asthma attacks, strokes, various cancers and cardiovascular problems. Asthma triggers Air pollution can cause problems for asthma sufferers for a number of reasons. Pollutants in traffic fumes can irritate the airways, and particulates can get into your lungs and throat and make these areas inflamed. Problems in pregnancy Women exposed to air pollution before getting pregnant are nearly 20 per cent more likely to have babies with birth defects, research suggested in January 2018. Living within 3.1 miles (5km) of a highly-polluted area one month before conceiving makes women more likely to give birth to babies with defects such as cleft palates or lips, a study by University of Cincinnati found. For every 0.01mg/m3 increase in fine air particles, birth defects rise by 19 per cent, the research adds. Previous research suggests this causes birth defects as a result of women suffering inflammation and 'internal stress'. What is being done to tackle air pollution? Paris agreement on climate change The Paris Agreement, which was first signed in 2015, is an international agreement to control and limit climate change. It hopes to hold the increase in the global average temperature to below 2°C (3.6ºF) 'and to pursue efforts to limit the temperature increase to 1.5°C (2.7°F)'. Carbon neutral by 2050 The UK government has announced plans to make the country carbon neutral by 2050. They plan to do this by planting more trees and by installing 'carbon capture' technology at the source of the pollution. Some critics are worried that this first option will be used by the government to export its carbon offsetting to other countries. International carbon credits let nations continue emitting carbon while paying for trees to be planted elsewhere, balancing out their emissions. No new petrol or diesel vehicles by 2040 In 2017, the UK government announced the sale of new petrol and diesel cars would be banned by 2040. However, MPs on the climate change committee have urged the government to bring the ban forward to 2030, as by then they will have an equivalent range and price. The Paris Agreement, which was first signed in 2015, is an international agreement to control and limit climate change. Pictured: air pollution over Paris in 2019. Norway's electric car subsidies The speedy electrification of Norway's automotive fleet is attributed mainly to generous state subsidies. Electric cars are almost entirely exempt from the heavy taxes imposed on petrol and diesel cars, which makes them competitively priced. A VW Golf with a standard combustion engine costs nearly 334,000 kroner (34,500 euros, $38,600), while its electric cousin the e-Golf costs 326,000 kroner thanks to a lower tax quotient. Criticisms of inaction on climate change The Committee on Climate Change (CCC) has said there is a 'shocking' lack of Government preparation for the risks to the country from climate change. The committee assessed 33 areas where the risks of climate change had to be addressed – from flood resilience of properties to impacts on farmland and supply chains – and found no real progress in any of them. The UK is not prepared for 2°C of warming, the level at which countries have pledged to curb temperature rises, let alone a 4°C rise, which is possible if greenhouse gases are not cut globally, the committee said. It added that cities need more green spaces to stop the urban 'heat island' effect, and to prevent floods by soaking up heavy rainfall. Share or comment on this article: The great climate paradox: Drop in air pollution has INCREASED global warming by making clouds less reflective, scientists warn Add comment
