Summer rains in western China have nearly doubled in the past 50 years because of climate change, posing an unexpected threat to Belt and Road Initiative projects in Xinjiang and central Asia, according to a new study.
The risks of flooding in one of the driest regions on Earth meant quality standards and design of infrastructure should be “updated to include a thought for water, lots of water”, warned the lead scientist of a study published on Monday by Chinese journal Scientia Sinica Terrae. The research team also called for more weather monitoring stations to improve the accuracy of forecasts in the remote region.
Zhang Xiaojian, an atmospheric physicist with Nanjing University who led the study, said some precautionary measures should be taken as soon as possible. “The design and construction of these infrastructure [projects] have not considered flooding. We recently saw as much rain come down in a few hours as would normally [be expected over] several years.”
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The belt and road plan is China’s ambitious programme to create a new Silk Road linking Asian, European and African countries with infrastructure construction, trade and investment. In the country’s remote western region of Xinjiang, this has meant a number of massive projects, including bridges, dams, railways and roads.
Urumqi, Xinjiang’s capital, is further from the sea than any other city on the planet. The region’s water supply has traditionally come from mountain snows brought in by westerly winds from the Black Sea and Mediterranean in the winter. Urumqi’s per capita water resources are only about one-eighth of the national average.
But western China, which is known for its deserts – including the Gobi, Asia’s second largest – is greening. Satellite images of Xinjiang show shrinking sands and expanding oases. The amount of summer rainfall has grown from about 100mm (3.9 inches) in the 1950s to 190mm (7.4 inches) in 2019, according to government weather records.
Scientists have been puzzled by where the extra water has been coming from. It has not originated from the west and most of the Indian monsoon to the south is blocked by the Tibetan plateau. Inadequate data from Xinjiang – about three times the size of France with many uninhabitable areas – added to the research challenge, Zhang said, with considerably fewer weather stations than other parts of the country.
With the help of a new computer model, Zhang’s team found the rainfall was originating mostly from the Pacific, a source previously believed impossible at more than 2,500km (1,550 miles) away. As global temperatures have increased, the Mongolian plateau has heated up and the hot air could force a typhoon in the western Pacific Ocean to extend its rainbelt westward all the way to Xinjiang.
According to the researchers’ estimates, the Pacific vapour will continue to advance further inland as global temperatures rise. Increased temperatures on the Tibetan plateau could also help parts of the Indian monsoon to move further north through a narrow corridor in Southeast Asia, though it would carry less water than from the Pacific, they found.
The researchers said Xinjiang was becoming as wet as it was about 2,000 years ago during the Han dynasty (206BC-AD220), which defeated the nomadic Huns and built the ancient Silk Road that sent Chinese products to markets as far away as Rome. Temperatures at that time are believed to have been on a par or even higher than today, with bamboo forests growing in the valleys of the Yellow River. The scientists said they believed the wet climate had contributed to the establishment of the Silk Road.
While the regreening of Xinjiang could be good news for the regional economy, the rains were not falling evenly throughout the year, according to the study. The rainfall was only occurring in summer, and sometimes over just a few days, with reports of flooding-related deaths in Xinjiang almost every year in recent decades. “The situation is getting worse and worse,” Zhang said.
The study is not the first to warn of the dangers climate change could pose to China’s belt and road strategy. Research last year led by Zhai Jianqing with the National Climate Centre in Beijing also warned that extreme weather could get in the way of infrastructure projects being built in many countries by Chinese companies.
Zhai and his colleagues found that countries along the belt and road accounted for more than 80 per cent of the global deaths caused by meteorological disasters from 1980 to 2019. The number of disasters between 2010 and 2019 increased nearly three times from the previous decade, most of them caused by flooding.
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