Global warming will threaten the prosperity of what will be the bigggest economy in the world.

“China faces extremely grim ecological and environmental conditions under the impact of continued global warming and changes to China’s regional environment.” says the 710-page report.

That will have a big knock-on effect on how China is able to feed itself. Global warming fed by greenhouse gases from industry, transport and shifting land-use poses a long-term threat to China’s prosperity, health and food output, says the report.

Under different scenarios of greenhouse gas levels and their effects, by the end of this century China’s average atmospheric temperature will have risen by between 2.5 degrees and 4.6 degrees Celsius above the average for 1961-1990.

Water, either too much or too little, lies at the heart of how that warming could trip up China’s budding prosperity.

“Climate change will lead to severe imbalances in China’s water resources within each year and across the years. In most areas, precipitation will be increasingly concentrated in the summer and autumn rainy seasons, and floods and droughts will become increasingly frequent.” says the report.

“Without effective measures in response, by the latter part of the 21st century, climate change could still constitute a threat to our country’s food security.” it says.

Under one scenario, by 2050 eight of mainland China’s 31 provinces and provincial-status cities could face severe water shortages and another 10 could face less dire chronic shortages.

“Since the 1950s, over 82 percent of glaciers have been in a state of retreat, and the pace has accelerated since the 1990s.” the report says of China’s glaciers in Tibet and nearby areas that feed major rivers.

China, with 1.34 billion people, already emits a quarter of the world’s CO2, with the United States the world’s second largest greenhouse gas emitter.

The report forecasts China’s CO2 emissions could reach between 9 and 9.5 billion tonnes in 2020 up from 8.3 billion tonnes in 2010, representing annual growth of 10.4 percent.

China is the world’s biggest consumer of cereals and has increasingly turned to foreign suppliers of corn and soy beans.

The report was written by teams of scientists supervised by government officials.

“Generally, the observed impacts of climate change on agriculture have been both positive and negative, but mainly negative.” Lin Erda, one of the chief authors of the report, said.

“But steadily, as the temperatures continue to rise, the negative consequences will be increasingly serious.” said Lin, an expert on climate change and farming at the Chinese Academy of Agricultural Sciences.

“For a certain length of time, people will be able to adapt, but costs of adaptation will rise, including for agriculture.”