China on alert amid extreme heatwave

China's 'big heat'

China will suffer the return of more heatwaves over the next 10 days from east to west, with some coastal cities already on their highest alert level and inland regions warning of dam failure risks because of melting glaciers.

A sharp temperature spike is expected on Saturday, before building up into heatwaves, defined as periods of atypically hot weather of three days or more. This Saturday is the day of the "big heat" in the Chinese Almanac based on the lunar calendar.

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Red alert in Zhejiang province

The hot spell is expected to be similar in scope as heatwaves from July 5-17, but more regions could be hit by temperatures of 40 degrees Celsius or higher, Fu Jiaolan, chief forecaster at the National Meteorological Centre, told state media.

Some cities in Zhejiang province, home to many factories and exporters, on Friday issued red alerts, the highest in a three-tier warning system, forecasting temperatures of at least 40C in the next 24 hours.

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'We have regulations that need to be followed'

The load on the national power grid could reach a new high this summer as demand for air-conditioning by homes, offices and factories surges, with safe operation facing "severe tests", the Ministry of Emergency Management warned on Friday.

"For all of the factories in China and in Shanghai we have regulations that need to be followed," said Leo Zhang, president of chemical product maker Sika China.

"Every year we do things to make the work more comfortable, for example giving workers ice-creams when it gets too hot."

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Risk of forest fires

Zhejiang, as well as parts of Fujian, Guangdong, Hunan, Jiangxi and the city of Chongqing, also stand at risk of forest fires in the near term, the ministry said.

In the western region of Xinjiang, accelerated glacial melt through July 29 poses risks to rivers and dams, the China Meteorological Administration said on Friday, warning particularly of a high risk of dam failure on a tributary of the Aksu River near China's border with Kyrgyzstan.

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Extreme heatwave

This round of hot weather will have "a certain degree of impact" on the melting of alpine snow and ice, the administration said.

The heat in China this summer has been described as extreme.

From June 1 to July 20, the Yellow River and Yangtze River basins - major centres of industry and commerce - were hit by at least 10 high-temperature days more than the norm.

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Climate change

Heatwaves have also scorched other parts of East Asia, Western Europe, North Africa and North America, sparking wildfires in many countries.

Scientists caution that climate change will only make heatwaves hotter and more frequent.

The highest-ever recorded temperature in China is a matter of debate.

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China's hottest temperature

According to Chinese media, the hottest period in the last 300 years was in July 1743 during the Qing dynasty, with a French missionary in Beijing said to have recorded an all-time high of 44.4C.

In 2015, a local news portal reported 50.3C at a weather station near Ayding, a dry lake in Xinjiang's Turpan Depression.

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Ozone pollution

Temperatures in the oasis city of Turpan could reach 50C next week, said the China Meteorological Administration on Friday.

The Climate and Clean Air Coalition estimates that ozone pollution causes approximately one million additional deaths per year.

Ozone is also a key concern for agricultural regions and food security. 

In January, researchers estimated that persistently high levels of ozone pollution in Asia are costing China, Japan and South Korea an estimated $63 billion annually in lost rice, wheat and maize crops.

(Photograph:Reuters)