MILDER conditions in the Arctic could be weakening winds in China and India, making winter smogs worse.
Burning fossil fuels can result in severe clouds of pollution in many cities in Asia, including Beijing and Delhi. These smogs 鈥� aerosols of fine particles 鈥� are worse in winter, when more fuel is used for heating and weather patterns that can cause dirty聽air to linger tend to take hold.
Advertisement
Chuanfeng Zhao at Beijing Normal University in China and his colleagues wondered if rising temperatures in the Arctic affect this. Going as far back as 1980, they compared the monthly average temperature of the Arctic with atmospheric aerosol levels of the northern hemisphere鈥檚 mid-latitude regions, where many industrialised cities are. They found that, when the聽Arctic had a particularly warm summer, aerosol concentrations in than usual the following winter.
This could be because warmer conditions in the Arctic reduce temperature differences in the northern hemisphere. The result may聽be a weakening of high-speed winds that normally blow eastwards. Less pollution could then get dispersed, causing aerosols to build up in some areas. Big mountain ranges, including the Himalayas and central China鈥檚 Qingling peaks, may block air flow further.
Zhao says his team鈥檚 work should enable governments to predict smog levels based on Arctic temperatures, 鈥渟o they can come up with better mitigation plans鈥�. But Tim Garrett at the University of Utah says the study only shows that Arctic warming and smogs are associated 鈥� it is unclear if one leads to the other.
Meanwhile, Arctic sea ice probably reached its maximum extent for 2019 on 13 March. Initial measurements put this at 14.8 million square kilometres, the joint-seventh lowest figure in the past 40 years.
