China science

Drought may cost China US$47 billion a year as temperatures rise, study finds

Researchers say economic losses will more than double if the global average goes up by 1.5 degrees – and a 2-degree increase would be significantly worse

PUBLISHED : Tuesday, 02 October, 2018, 8:31pm
UPDATED : Tuesday, 02 October, 2018, 11:29pm

Drought conditions could cost China US$47 billion per year in economic losses – more than double the current estimate – if global temperatures rise by 1.5 degrees Celsius above the pre-industrial baseline, according to a Chinese study.

Those losses could climb a lot higher – to US$84 billion, or about five times this year’s level – if the global average temperature goes up by 2 degrees, Chinese Academy of Sciences researchers found.

Their study, published in US journal Proceedings of the National Academy of Sciences on Monday, projected China’s economic losses from drought under the two rising temperature scenarios, using climate data from 31 provinces over the three decades from 1986 to 2015.

The two scenarios were based on the target set by the Paris Agreement to tackle climate change, which aims to limit global warming to 1.5 or 2 degrees above pre-industrial levels.

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“Drought losses have significantly increased in recent years across the globe,” said Jiang Tong, lead author of the study and a researcher with the National Climate Centre at the China Meteorological Administration in Beijing. “[But] most projections agree that the warming rate of China will be faster than the global mean.”

At present, China’s economic losses from drought are estimated at US$17.7 billion per year, based on the average from 2006 to 2015, according to the study.

The losses could be significantly worse if temperatures continue to rise, since China’s arable land – some 135 million hectares – represents 10 per cent of the world’s total, and supports one-fifth of the global population, Jiang said.

The study found that more than 20 million hectares of crops in China – an area about the size of Indonesia – have been affected by drought every year since 1949, damaging the productivity of one-sixth of the country’s total arable land.

“[But] keeping the global average temperature increase under or equal to 1.5 degrees Celsius above the pre-industrial level could reduce annual drought losses by several tens of billions of US dollars, as the projected losses under the 2 degrees scenario nearly double those under 1.5 degrees,” he said.

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Climate change is projected to take a bigger toll in southern China, a region considered to be humid, as severe drought events have occurred more frequently than before in the years since 2010, the study found.

“Compared with precipitation, the evapotranspiration increase is more obvious in southern China,” according to the study. “And evapotranspiration plays a major role in the generation of droughts in the warmer world.”

Evapotranspiration refers to water loss from the ground to the atmosphere through evaporation from the soil and transpiration from plants.

The researchers expected that much of China – nearly 75 per cent of the country except for the northeastern area – will be drier in the future. And over half of that area is forecast to experience more intense drought conditions if temperatures rise by 2 degrees Celsius, compared with an increase of 1.5 degrees.

“Annual average drought loss for the 2 degrees Celsius warming level in the growth-oriented model is estimated to be around two times that in the 1.5 degrees warming [scenario],” said Su Buda, a co-author of the study and a researcher with the Chinese Academy of Sciences.

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The study called for efforts to limit warming to 1.5 degrees because economic losses at that level would be significantly lower than if temperatures rose by 2 degrees, she said.

In the two decades to 2005, the average global surface temperature was 0.61 degrees Celsius warmer than the pre-industrial level, according to the UN’s Intergovernmental Panel on Climate Change.

The Paris climate pact was signed in 2016 by 180 countries, including China and India, though the United States has said it plans to withdraw from the agreement.