Air pollution, which causes millions of deaths each year, is actually shielding the Earth from the full force of the sun, according to a group of scientists. The conclusion was reached after studying the results of China’s successful “war on pollution,” which reduced sulphur dioxide (SO2) emissions by nearly 90% and saved tens of thousands of lives. However, the removal of this toxic shield has led to a rise in average temperatures in China, triggering more intense heatwaves. The scientists warn that if other highly polluted regions, such as India and the Middle East, follow China’s lead in cleaning up pollution, they too will experience increased warming.
The scientists explained that air pollution, specifically aerosols formed by sulphur dioxide, scatters and reflects solar radiation, thereby reducing the amount of sunlight that reaches the Earth’s surface. This phenomenon, known as “unmasking,” has a significant impact on temperatures. The review of meteorological data shows that China’s average temperatures have increased by 0.7 degrees Celsius since 2014, with even greater warming in heavily industrialized regions. If similar efforts to improve air quality are implemented in other regions, it could push the world into catastrophic warming scenarios with irreversible consequences.
The IPCC highlighted the link between reducing sulphur dioxide and global warming in a recent report, stating that without the solar shield of SO2 pollution, the global average temperature would already have risen by 1.6 degrees Celsius above preindustrial levels. This exceeds the goal of limiting warming to 1.5 degrees Celsius, beyond which irreversible and catastrophic changes to the climate are predicted.
The scientists stressed that the fight against air pollution should continue due to its immediate health impacts, but more aggressive action is needed to reduce greenhouse gas emissions. They identified reducing methane emissions as one of the most promising ways to offset the effects of pollution unmasking in the short term. Methane has a shorter lifespan in the atmosphere compared to carbon dioxide, so cutting emissions would yield faster results.
China’s “war on pollution” began in 2013 when President Xi Jinping pledged to tackle the country’s severe pollution problem. The government implemented various measures, such as using lower-sulfur coal and tightening vehicle fuel standards, resulting in a significant reduction in SO2 emissions. However, the review of data shows that the drop in pollution was accompanied by a rise in temperatures, particularly in heavily industrialized regions.
The effects of pollution unmasking are most pronounced in developing countries like India and the Middle East, where sulphur pollution is still increasing. The scientists warned that these regions would also experience significant warming if they followed China’s lead in reducing pollution.
To counter the associated warming, experts are exploring methods such as injecting sulphur aerosols into the atmosphere or curbing methane emissions. While the injection of aerosols could cool temperatures, it carries the risk of unintended consequences. Therefore, many scientists view reducing methane emissions as the most effective solution, as its effects on global temperatures are short-term compared to other greenhouse gases.
In conclusion, the reduction of air pollution is essential for public health but must be accompanied by aggressive actions to reduce greenhouse gas emissions. The unmasking of pollution, while leading to increased warming, highlights the need for a comprehensive approach to tackle climate change.