BEIJING — Rising seas besieging China's economically vital coastal zones. Mighty feats of infrastructure, like the Three Gorges Dam and railway in Tibet, strained by turbulent rainfall and the melting of frozen earth. And on the Himalayan frontiers, the risk in future decades of international conflict over dwindling water supplies as glaciers retreat.
These and other somber situations 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," Zhang Haibin, a professor at Peking University who was among some 550 experts who prepared the report, said in an interview. He noted a shift since the first such assessment was issued nine years ago. "From the first to the second to this third report, the negative impacts of climate change on China are increasingly apparent."
The new report went on public sale in recent days after its release by the Ministry of Science and Technology, and is available only in Chinese.
It 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. And 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, one section of the report urges Beijing to be more flexible in negotiations, where 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.
The latest talks start in Paris Monday, and Chinese President Xi Jinping will be among the leaders at the opening. Xi will restate China's long-standing position that it is still a poor, growing country, meaning it should not bear the responsibility for quantitative greenhouse-gas caps that apply to rich economies, the Chinese foreign ministry said Friday. Yet one section of 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 900-page study, "The Third National Climate Change Assessment Report," is not a summation of established government policy; rather it is a distillation of the latest science and policy options from state-appointed experts. Some of them likened it to the United Nations Intergovernmental Panel on Climate Change, which summarizes advances in scientific research and their implications, with authors sometimes contradicting one another.
"It is an important contribution to debates and to the process of building consensus," said Qi Ye, a professor of environmental policy and management at Tsinghua University in Beijing who contributed to the report. "In that regard, it does contribute to the policymaking process, albeit indirectly."
The report acknowledges disagreement among policy advisers over how many years China's emissions will keep growing before they level off.
He Jiankun, a professor at Tsinghua University who was a senior author of the report, said he hoped that the government would embrace its proposal for firm coal consumption and carbon-dioxide pollution limits from next year, paving the way for a peak in emissions before the 2030 date proposed by the government.
China's current goals try to reduce the carbon-dioxide pollution released for each unit of economic growth. That means that emissions still grow, but more slowly than the economy, and there is no absolute ceiling on those emissions.
"Without a goal, your future emissions might be even higher," He said.
The effects of climate change are already coursing through the environment. The report urges more spending on preparing to cope with increasingly frequent and extreme droughts, floods and heat waves.
Rising sea levels are among the threats that receive the most attention in the report. As polar ice melts and ocean temperatures rise, seas across the world are swelling, but the changes are uneven, and the waters off China's coast have been rising faster than the global average, the report says.
"Some cities may even face risks of massive disasters that are hard to forecast," it says.
While there is much debate about the extent of future rises, the report cites projections that, by the end of this century, the sea off eastern China could rise between 16 and 24 inches, or 40 and 60 centimeters, compared to 20th-century averages, exposing cities like Shanghai and nearby areas to tidal inundations and more severe damage from storms and typhoons. Some projections are even higher.
"Every piece of infrastructure built on the coast is potentially vulnerable," Isabel Hilton, the editor of Chinadialogue, a website for news and discussion of the country's environmental challenges, said in a telephone interview. "That's a huge amount of GDP you have there."
Inland China will experience major shifts in rain and snowfall, which will reshape agriculture. Rising temperatures also mean air absorbs more moisture, which is then likely to be dumped in increasingly erratic rainfall, especially in northern China. Overall, the report says, China's water resources, already strained, could shrink by 5 percent by midcentury, because of climate change.
That will demand major changes in farming, and could strain the Three Gorges Dam, one of the world's largest, says the report. Changing rainfall patterns will eventually mean that the dam endures more frequent shortfalls in dry seasons and more intense floods in wet seasons. This will be "extremely detrimental to reservoir management, dam safety and flood prevention," says the report.
Across Tibet and other high-altitude regions of western China, glaciers have been retreating, as has permafrost: the layer of earth below the surface that remains frozen throughout the year. China's glaciers shrank by 10 percent between the 1970s and the early 2000s, and the permafrost had retreated by about 26 percent by 2012, says the report.
China's 710-mile railway line across the Tibetan Plateau is already being unsettled by the softening, unstable ground, which causes the warping of tracks. The pace of warming threatens to outpace technological remedies, the report says.
The risks to China from these changes are not only environmental or economic; one section of the report is devoted to the national security implications.
"The shrinking of river flows caused by the melting away of glaciers in western China may lead to struggles over cross-border water resources and surges of transnational migration, triggering international disputes and conflict," according to the report. "Overall, climate change could have a broad impact on China's national security, but for now that is mainly latent."