South China Morning Post
Stephen Chen
October 16, 2015
Water-starved northern China could benefit as the thermal equator moves northward, bringing seasonal Asian rains upcountry, team finds
Scientists remain divided over whether global warming is exacerbating the droughts in northern China or not. But the latest findings suggest the phenomenon will make the region greener and wetter if it continues. Photo: SCMP Pictures
Global warming will benefit China by increasing rainfall in its dry northern regions while reducing flooding in the hotter southern areas, according to a new study by scientists in the country.
The research team from the Chinese Academy of Sciences said that if the phenomenon continues, the planet’s thermal equator will move northward and push the rain belt associated with the monsoons in East Asia from the southern to northern part of the country.
The thermal equator is made up of a set of locations encircling the planet that have the highest mean annual temperatures at each longitude.
If such climatic change were to occur in China, bamboo forests would reappear along the banks of the Yellow River, which runs from Qinghai province in the far west and empties into the Bohai Sea in Shandong province on the eastern coast, pundits predict.
Moreover, rice paddies would likely expand to the Great Wall, which runs along the dry northern part of China, and Beijing, which faces chronic water shortages, would no longer need to channel water from the south.
In their recent paper published in the influential research journal the Proceedings of the National Academy of Sciences of the United States of America, a team of scientists led by Professor Yang Shiling
reported that such a paradigm shift would “soon occur” in China.
China’s Yang works with the academy’s Institute of Geology and Geophysics.
Northern China would “eventually become wet as global warming advances,” the team concluded in the paper.
Flooding in southern China claims many lives each year and causes significant economic losses. Photo: SCMP Pictures
The evidence supporting their claim is buried deeply under the Loess Plateau, the cradle of Chinese civilization in the upper and middle reaches of the Yellow River.
The team analysed the carbon signatures of plant biomass after the last Ice Age, which ended about 20,000 years ago, and found the monsoon belt had moved northward as much as 300 kilometres as temperatures rose globally.
The scientists predicted that the same trend will be repeated in the future as the planet again heats up. However it should spell good news for China as the dry climate plaguing the northern parts of the country will be alleviated by more rainfall if global warming continues, they said.
The new finding challenges the traditional view that global warming will exacerbate water shortages in this part of the world.
In recent decades the Asian monsoon rain belt has moved southward. As this coincided with rising temperatures globally, the mainstream Chinese scientific community feared that the northern droughts and southern flooding now seen in China each year ranked among the disastrous results of climate change.
Such fears helped build support for the construction of China’s Three Gorges Dam and the South-North Water Transfer Project, two of the world’s largest engineering projects to fight flooding and water shortages, respectively.
But Beijing, like other parts of northern China including far western Xinjiang province, have recorded increasing – rather than decreasing – levels of rainfall in recent years.
In 2012, the Chinese capital was hit by the biggest rainstorm in more than six decades, with nearly 80 people killed.
Coral bleaching, as shown here in American Samoa, is one of the nefarious effects of global warming along with receding coastlines as glaciers melt and sea temperatures rise. Photo: AP
Scientists also found that the deserts of Xinjiang and Inner Mongolia were retreating due to the expansion of grasslands and forests.
One earth scientist who is familiar with Yang’s research said the new findings provide fresh and important information to help us understand climate change’s impact on China and the rest of the planet.
“Their claim seems credible over a long time period, that is, in terms of patterns that repeat every few thousands of years,” said the researcher at Lanzhou University in Gansu province. He declined to give his name due to the political sensitivity of such issues in China.
“But whether northern China will get wetter in the next few decades remains open for debate,” he said. “Observations over the last few decades tend to contradict their claim. We’ve seen that northern China got drier at either the same – or faster – pace than global warming.”
He said the latest findings should not be taken as an excuse to ditch ongoing efforts to mitigate the negative impacts of global warming.
Though droughts and flooding rank among the top concerns of local scientists and the Chinese government, other issues like rising sea levels and melting glaciers must also be combated by a concerted global effort to cut greenhouse gas emissions, experts say.
Debate about the trade-off between the costs and benefits of climate change continues to rage to this day.
While large international authorities such as the United Nation’s Intergovernmental Panel on Climate Change have vowed to tackle climate change head-on, some scientists and organisations believe it may help boost the production of crops and forests, among other benefits.
In a report published Monday the Global Warming Policy Foundation, a London-based think tank, said that all the carbon dioxide being dumped in the atmosphere has helped boost crop production to the tune of US$140 billion a year in recent times.
The foundation has called for a reassessment of the impact brought on by greenhouse gas emissions.
