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Climate change: China's capacity to cope

For almost thirty years, China's economy has far outstripped world growth rates, increasing by almost 10 per cent each year. Millions of Chinese are now eating more meat, driving cars and spending their fast-rising incomes. But this vast country, home to a fifth of the world's population has only 7 per cent of global arable land. Land and water are already key constraints to China's agricultural production and harvests have fallen annually since 1998. Deforestation, grazing and intensive cultivation have also taken their toll, such that China, once self-sufficient in grain, has rapidly become the world's largest importer of wheat. With average temperatures across China predicted to rise 3-4ºC by the end of this century, yields of three staple crops (rice, wheat and maize) are predicted to fall by over a third. The impact of climate change in China is expected to be considerable.

"Climate change without CO₂ fertilization could reduce crop yields in China by up to 37 per cent in the next 20 to 80 years," reported Professor Lin Erda of the Agrometeorology Institute of the Chinese Academy of Agricultural Sciences, who led a British-funded study on the impact of climate change on China. He added that fertilisation may mitigate this loss to a degree, but the extent of this effect is uncertain and that elevated CO₂ is also likely to have a deleterious effect on grain quality.

Risks and benefits

Arid land in DEFRA study area - Ningxia province, China
Cinzia Losenno, DEFRA

Regional climate models, developed by the UK's Hadley Centre for Climate Prediction and Research have predicted that as global warming occurs, Chinese winters will become less cold but there is a greater likelihood of high summer temperatures and a rise in the number of days of heavy rainfall. Warmer temperatures would favour increases in cotton yields, an important cash crop in China, although extreme temperatures would significantly reduce harvest potential. China's most important crop, rice, is predicted to expand in area under climate change although this will almost certainly be constrained by insufficient water for irrigation. Maize can adapt to a wide range of temperature and rainfall and is grown in most parts of China. Harvests are predicted to increase in some areas by 2080 but overall yields in most major production areas will be affected by scarcity of water and high temperatures that would particularly impact on grain swelling.

The modelling work for China, funded by the UK Department of Environment, Food and Rural Affairs (DEFRA) took account of variations in climate, soil and CO₂ levels, but did not look at water availability or the likely impact of pests and diseases. Results were published in 2004. The study also looked for the first time at how socio-economic development could have an impact on Chinese agriculture. One of the key conclusions was that under a continuing high economic growth scenario, the land available for agriculture would be severely reduced. Urbanisation would play its part. Moreover, according to Lester Brown of the Earth Policy Institute, if China were to reach Japan's car ownership rate of one vehicle for every two people, the equivalent of two-thirds of the land currently devoted to rice farming would have to be paved.

Ways to adapt

China currently accounts for nearly 15 per cent of the world's greenhouse gas emissions and, as the country becomes rapidly more industrialised, experts predict that within two decades Chinese emissions will be greater even than those of the United States. Yet, as a developing country, it is not required to limit its emissions under the internationally agreed Kyoto Protocol. However, scientists agree that climate change will affect China, and China will affect climate change and that it will need to take steps to reduce its own emissions as well as introduce mitigation measures to counteract the impact of climate change on Chinese food security.

Some of the ways in which China could adapt its agriculture, proposes Lin, include breeders developing and promoting crop varieties that are more readily fertilised by CO₂. Expanded irrigation infrastructure, water-saving technologies and heat-resistant crops would also enable farmers to cope with expected higher temperatures and water shortages. "The planting distribution of crops should be adjusted to take advantage of a warmer climate in north-east China in next 20-30 years," he stressed, "and efforts should be made to stem desertification and so maintain grasslands for herds."

In the meantime, a further study to explore the likely effects of climate change on water availability and carbon dioxide fertilisation and the impacts this will have on projected crop yields in China is to be funded by DEFRA, involving both Chinese and British scientists.

Date published: July 2005

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