Weatherwatch: Cleaning up air pollution has made winters milder

Will we ever see another winter as bitter as this? Farm workers use a pneumatic drill to get parsnips out of frozen earth in February 1947. Photograph: Keystone/Getty Images

Since the 1960s winters across Europe have become milder, and in the UK our winters have become warmer and wetter. Big snow dumps are less common now. Much of this change can be blamed on anthropogenic global warming, but it turns out that Europe’s efforts to clean its skies have also reduced the likelihood of harsh winter weather.

Air pollution can have a significant impact on our climate. Some pollutants, like sulphate particles, scatter radiation and cause cooling. Air pollution can also change cloud properties. Since the 1970s countries across Europe and North America have significantly curbed their air pollution, resulting in more of the sun’s energy reaching Earth’s surface over these locations.

Yuan Wang, from the California Institute of Technology, and colleagues have input air pollution data (gathered between 1970 and 2005) into climate models to investigate how cleaner skies may have impacted atmospheric circulation patterns and extreme weather. Their results, published in Nature Climate Change, reveal that the reduction in air pollution has altered the strength and location of high altitude winds, shifting the jet stream further to the north during winter. This change has suppressed cold extremes over northern Eurasia. Future pollution reduction over China is expected to exert a similar influence.