We need to prepare to deal with more heat waves

As an intense heat wave sweeps through China, residents are seeking relief in air raid shelters and swimming pools to stay cool, and dozens of cities, including Shanghai, Chongqing and Hangzhou, have issued their highest-level red alert warnings. The heat wave has even claimed a few lives.

Shanghai has issued three red alerts this year, with the temperature hitting 40.9 Celsius on July 13 according to Shanghai Meteorological Service, matching the record set in 2017 since 1873. The fact that Shanghai has experienced only 16 days of 40 C-plus temperatures since the city began keeping records in 1873 should give us an idea about the seriousness of the situation.

Medical experts say extreme heat could cause nausea, profuse perspiration, fatigue, sunstroke, epilepsy, even death, with senior citizens and people with long-term illnesses particularly vulnerable to heat waves.

Extreme heat events, which began a month ago, have affected the lives of more than 900 million people across 5 million square kilometers in China. Between June 1 and July 12, the average number of days with temperatures above 35 C was 5.3, up 2.4 days over normal years, breaking the national record set in 1961, according to the National Climate Center.

Each extreme weather event is accompanied by a special synoptic pattern (or patterns). Specifically, the shift of the rain band from the Yangtze River Delta region to the North and the East, which ended the Mei-yu, the elongated rainband extending from the Yangtze River to Japan in mid-summer, earlier than usual on July 8, left the region in the grip of strong subtropical high which resulted in the heat wave.

The 20 percent shortfall in rainfall across the country conforms to La Niña－cooling of the surface water of the eastern and central Pacific Ocean every two to seven years, which often brings about drought in the Yangtze River Delta region.

The heat waves in China and Europe, which is also experiencing record-high temperatures, reflect the more unstable weather patterns amid intensifying global warming. In fact, average global temperature has increased by about 1.2 C compared with 100 years ago.

But since the effects of global warming are not even, different regions are experiencing extreme heat waves during different phases of summer, even different years. This year the Yangtze River Delta region and eastern China, along with parts of Europe are in the grip of heat waves and experiencing extreme weather events after the western part of North America faced extreme heat waves last year. In response to the exceptionally high temperatures, the United Kingdom has declared a national emergency and issued the highest-level red alert warning for Monday and Tuesday for the first time.

More alarmingly, the average global temperature in June this year was 0.4 C higher than normal years and the highest since 1979, the National Climate Center said, with temperatures in countries such as Spain, France and Italy exceeding 40 C.

Unfortunately extreme heat, which is directly related to climate change, will become more frequent and intense in the next 30 years, setting new records for high temperatures. As global warming intensifies, losses and devastations will increase, forcing natural and human systems to raise their adaptation limits, according to the UN Intergovernmental Panel on Climate Change Sixth Assessment Report.

China and some other countries have set deadlines for peaking their carbon emissions and achieving carbon neutrality in order to mitigate the effects of climate change. But extreme weather events including heat waves, intense rainfall and typhoons could become more frequent, and concerted efforts will be required to deal with them.

But since heat waves are likely to become more frequent, cities would do better to incorporate extreme weather events including heat waves into their emergency－or disaster-management planning. Indeed, a few cities, Guangzhou for instance, are using passive cooling techniques to reduce the impact of heat waves.

Also, urban authorities should introduce special measures and build facilities to ensure people engaged in sectors that require working even in extreme heat conditions do so without endangering their health. Actually, special allowances should be given to such workers for working under extremely stressful and hazardous conditions.

But in the ultimate analysis, the world has to give up its business as usual and take sincere measures to cut carbon emissions, by reducing the use of fossil fuels and stopping the destruction of forests, to fight climate change and prevent the planet from overheating and causing more miseries for humans, who incidentally are to blame for climate change in the first place.

The author is an associate research fellow at the Institute of Atmospheric Physics, Chinese Academy of Sciences.

The views don't necessarily represent those of China Daily.

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