China's sweeping efforts to clean up its air have delivered one of the biggest public health success stories of recent decades. Since the Air Pollution Prevention and Control Action Plan was launched in 2013, coal-fired power plants have been fitted with scrubbers, heavy industry has been modernized and pollution standards tightened, leading to an over 50% reduction in atmospheric particulate matter.

In the atmosphere, sulfur dioxide forms sulfate aerosols, tiny particles that reflect incoming solar radiation back into space, leading to a cooling influence on the plane

The combined aerosol radiative forcing is thought to have offset approximately one-third of global warming caused by greenhouse gas emissions. However, as emissions fall, fewer sulfate aerosols form, meaning less sunlight is reflected and more solar radiation reaches Earth’s surface, contributing to global warming.