BEIJING — Rising seas besieging China's economically vital coastal zones. Mighty infrastructure, like the Three Gorges Dam and railway in Tibet, strained by turbulent rainfall and glacial melting. And on the Himalayan frontiers, the risk in future decades of international conflict over dwindling water supplies.
These and other somber prospects are laid out in the Chinese government's latest scientific assessment of global warming, released just before negotiations in Paris for a new international agreement on climate change.
"There's deepening awareness of the gravity of the problems," said Zhang Haibin, a professor at Peking University who was among some 550 scientists who prepared the report. He noted a shift since the first such assessment was issued nine years ago.
The Chinese government said Sunday that it had achieved its annual target for reducing major pollutants, ending 2015 ahead of schedule. But air pollution reached "hazardous" levels in Beijing on the same day, prompting the city to upgrade to the second-highest pollution alert for the first time in 13 months.
The scientific report presents global warming as squeezing China from two fronts: the environmental hazards and the international response.
China is increasingly vulnerable to the effects of climate change, especially from rising seas and shifting rainfall and snow patterns. Yet it also faces growing international pressure to cut its greenhouse-gas pollution, which is by far the most of any country, almost twice that of the second-place country, the United States.
To ward off those international demands, Beijing should be more flexible in negotiations, the report urges. China's dual status as a huge developing economy and the biggest polluter has generated friction with the European Union and the United States and other countries that want firmer commitments for when its greenhouse-gas output will start to fall.
Chinese President Xi Jinping will be among the leaders at the opening of the latest talks Monday. Xi will restate China's longstanding position that it is a poor, growing country, meaning it should not have the type of greenhouse-gas caps that apply to rich economies, the Chinese foreign ministry said. Yet the new report suggests that China will have to adjust to new demands.
"There is an unavoidable trend for all countries to participate in emissions cuts, and for the major developing countries to shoulder larger emissions-reduction responsibilities," the report said. "China must fully prepare for this."
The study is not a summation of established government policy; rather, it is a distillation of the latest science and policy options from state-appointed experts.