The deadliest place on earth for extreme heatwaves in the near future will be in the north China plain according to a Massachusetts Institute of Technology (MIT) study recently published in the journal Nature. This region is one of the most densely populated areas on Earth with a population of over 400,000,000 million people. It is also the most fertile region in China and it is frequently compared to the United States fertile mid-west for food production. The north China plain is the most important food-producing area in the huge nation that has 1.4 billion people. According to the authors, rainfall levels are quite low in this region compared to southern China. In order to farm the land, irrigation is necessary for supplementing soil water during the spring and early summer grow season.
The rainfall levels in the north China plain are relatively low compared to similar locations in southern China, making irrigation necessary for supplementing soil water during the spring to early summer grow seasons. “This fertile plain has experienced vast expansion of irrigated agriculture which impacts significantly the surface radiation, surface energy balance, and boundary layer development in ways that impact surface humidity, and temperature”.
One of the terms that we will become accustomed to is a Wet Bulb Temperature (WBT). Picture yourself standing outside in the shade, butt naked, with your skin soaking wet from perspiration while a fan blows on you. The inability of the skin to dry in those conditions prevents the body to cool itself leading to death within hours for a young and healthy human.
Damian Carrington writes in the Guardian:
“China is currently the largest contributor to the emissions of greenhouse gases, with potentially serious implications to its own population,” he said. “Continuation of current global emissions may limit the habitability of the most populous region of the most populous country on Earth.”
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The research, published in the journal Nature Communications, found fatal WBTs of 35C (95 F) would strike the north China plain repeatedly between 2070 and 2100, unless carbon emissions are cut. Shanghai, for example, would exceed the fatal threshold about five times and the “extreme danger” WBTs would occur hundreds of times. Even if significant carbon cuts are made, the “extreme danger” WBT would be exceeded many times.
Previous research by Eltahir and colleagues showed that the Gulf in the Middle East, the heartland of the global oil industry, will also suffer heatwaves beyond the limit of human survival if climate change is unchecked, particularly Abu Dhabi, Dubai, Doha and coastal cities in Iran. The fatal 35C (95 F) WBT was almost reached in Bandar Mahshahr in Iran in July 2015, where 46C (114.8) heat combined with 50% humidity.
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Climate change is the key driver, but the massive irrigation used on crops on the north China plain was found to be significant too, adding about 0.5C to the high WBTs. This is because the evaporation of irrigation water leads to higher humidity and because water vapour is itself a powerful greenhouse gas.
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