Scientifically Addressing Global Warming and Strengthening Food Security

From: English Edition of Qiushi Journal Updated: 2011-09-20 11:29
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 Climatic conditions in China are complex, the ecological environment is fragile, there are frequent natural disasters and the country is vulnerable to climate change. It is important for China to reduce the impact of global warming on its food security and improve the ability of agriculture to cope with weather-related risks as part of the effort to deal with climate change and promote sustainable agricultural development.

 I. The tremendous impact of global warming on China’s agricultural production and food security

 Extreme weather-related disasters are likely to become more and more frequent and severe around the world in the future. This will threaten global sustainable development, including the development of agricultural production. Agricultural production in China and the rest of the world will fluctuate greatly due to global warming and grain supply will become more unstable. 

 Studies show that for every 1-degree Celsius increase in temperature, agricultural yields will fall about 10 per cent. High temperature will shorten the time it takes for crops to reach maturity and reduce yields, probably offsetting any extension of the growing season. For every 1-degree Celsius increase in temperature, the growth period of rice in China will possibly be shortened by an average of 7 to 8 days and 17 days for winter wheat. Shorter growth period will shorten the period crops have to build up dry matter through photosynthesis, thus decreasing the quality of crops.

 Climate change will lead to low water content in China’s main crops, frequent natural disasters that affect agriculture and fluctuation in grain output. Natural disasters affecting agriculture, shortage of water resources and agricultural diseases and insect pests in China have become more severe under the influence of global warming. If several disasters were to strike at the same time or in adjacent regions, grain production would be severely affected, resulting in even greater reduction in output. At the same time, climate change has also contributed to greater loss of water, organic matter and nitrogen in the soil, accelerated soil degradation and erosion, and impaired the ability of the agricultural ecological system to resist natural catastrophes. Increasing temperatures will also lead to reduction of rainfall in arid regions, worsening of soil wind erosion and soil salinization, and increase in drying of the soil through evaporation in costal regions.

 Due to the effects of global warming, persistent drought over large areas has become the most serious threat to agricultural production. For example, China loses an average of 30 billion kilograms of grain annually due to drought, accounting for 60% of the total loss due to various natural disasters. Studies show that the drought problem in northern China that has already lasted more than 30 years will not improve in the next 10 years due to global warming. Moreover, the problem of seasonal droughts in southern China, which usually has abundant rainfall, has become more severe. Global warming has led to greater frequency and severity of extreme weather and weather events. The harm caused by drought has also become more severe and is affecting larger areas. For this reason, while addressing the threat of drought to agricultural production in northern China, we also need to worry about the impact of seasonal droughts and persistent drought on agricultural production in southern China.

 On the other hand, global warming also carries some benefit for agricultural production in some regions of China. More heat has become available in high-latitude areas, allowing heat-loving crops to be planted farther north. This has promoted the restructuring of cultivation. The climate has become warmer in northeastern China since the 1990s, allowing cultivation of rice further north. Yichun and Heihe, formerly not suitable for rice cultivation, have become rice-producing areas. Due to the rise in average temperature for the year, particularly the changes in weather conditions affecting the growing season for crops, between 1980 and 2000 the area suitable for planting rice in Heilongjiang Province expanded by a factor of 7, the main corn-producing area of the province shifted to the south and the wheat and soybean producing area shifted to the north, resulting in an increase in grain production of 10% to 13% over the last 15 years. The greater availability of heat also lessened the damage to crops caused by low temperatures, allowing an increase in the total area of cultivation and output of late-maturing crops. The time available for corn to mature in Jilin Province has been extended 7 to 10 days and the total growing area of high-yield late-maturing corn has increased rapidly. Due to the effects of global warming, the ideal time for planting crops is now earlier and the date when crops stop growing is now later in the area north of the Yangtze, especially in the middle latitudes and plateau areas, resulting in an extension of the potential cultivation season. This has led to changes in the current planting system and geographical pattern of cultivation and an increase in opportunities for multiple cropping. It is estimated that for every increase in temperature of 1.4 degrees Celsius and 4.2% increase in rainfall, the total area that can only sustain one crop per year decreases from 62.3% to 39.2%, the total area that can sustain two crops per year increases from 24.2% to 24.9%, and the total area that can sustain three crops per year increases from 13.5% to 35.9%. However, the increase in evaporation from the soil due to global warming will reduce the availability of water for some crops. Therefore, the benefit of increased heat may be offset by insufficient availability of water. Meanwhile, detrimental overuse of water resources for short-term gain to take advantage of the increased availability of heat will threaten the long-term food security of the country.

 In general, global warming will lead to a decrease in the potential productivity and stability of China’s main grain crops. Given China’s current level of production and security conditions, if we do not take effective measures to address climate change, annual yields of China’s main crops, such as wheat, rice, and corn, will drop by as much as 37% in the second half of the 21st century. Climate change and extreme weather events will lead to an increase of 10% to 20%, and perhaps 30% or more in extremely poor years, in the natural fluctuation in China’s grain production. Climate change will also lead to a decrease in global grain output and an increase in the fluctuation of grain production. It is estimated that by 2050, grain yields in South Asia may drop by about 30% in extremely poor years. There has been a dramatic decrease in the world’s grain reserves, making it more difficult for China to import grain. Prospects do not look good for China to make up for poor grain yields through grain imports. Climate change and unusual weather will also lead to increases in world grain prices due to changes in the grain output of major grain producing countries and major grain importing countries.

  Mengjin County, Henan Province is working hard to develop the methane gas industry in the countryside. There are now 44,500 household methane gas pools in the county covering 44.5% of all rural households in the county. The increased use of methane provides many rural households with a safe, environmentally friendly energy source and greatly improves their living conditions and survival environment. Even more importantly, the recycling agricultural production model thus created provides a considerable and stable increase in the incomes of local residents, and large numbers of model villages for environmentally friendly agriculture are emerging all over the county. This is an important measure in China’s efforts to address climate change, develop clean energy and improve living and working conditions. Pictured are farmers in Liang’ao Village, Mengjin County using residue from the production of methane as fertilizer in their covered plots for pollution-free vegetable crops. The village has become famous near and far for the vegetables they produce. / Photo by Xinhua reporter Wang Song

 II. Scientific and effective measures to address the threat to agricultural production posed by climate change

 As a large developing country, adapting to climate change rather than attempting to slow the change is the more practical and pressing requirement for China. Climate conditions directly impact and restrict the process of agricultural production. Because agriculture is extremely vulnerable to the effects of global warming, the highest requirements and greatest pressure for adapting to climate change come from agriculture. For this reason, we need to make adapting to climate change the top priority in China’s strategy for addressing climate change and make promoting agricultural production and safeguarding food security the top priority in China’s efforts to address climate change.

 We need to scientifically plan the agricultural production pattern to adapt to global warming. We need to pay close attention to and devote a great deal of energy to softening the adverse impact of extreme weather disasters and unfavorable weather conditions in efforts to increase and stabilize grain yields. The key is to step up efforts to establish a system to cope with and prevent agricultural disasters due to extreme weather in major grain crops and main grain-producing areas. We need to take truly effective and comprehensive measures, increase investment in efforts to combat damage to agriculture from extreme weather such as drought, flood, frost and high temperatures and from plant diseases and insect pests, build more water conservancy projects, strengthen agricultural infrastructure and continue working on the project to artificially influence the weather, and raise standards for projects to combat the effects of natural disasters on agriculture. We need to increase the potential productivity of agriculture and optimize the deployment of resources for agricultural production in order to ensure continued increase in agricultural output and long-term food security. We need to thoroughly analyze the future geographical distribution of sunlight, temperature and rainfall and the new pattern of extreme weather events affecting agriculture and carry out a survey of agricultural weather resources and how to take advantage of them to accelerate efforts to reclassify agricultural climate zones. We must formulate a new agricultural structure and distribution pattern of cultivation based on the current structure and pattern to adapt to the new pattern of sunlight, temperature and rainfall distribution and weather pattern to improve the utilization efficiency of climate resources as soon as possible.

 We need to safeguard food security through our own efforts. Because of the world-wide decline of potential productivity and increasing instability in the output of major grain crops due to climate change, all countries in the world, especially the developing countries, are facing the problem of food security to varying degrees. The amount of grain available in the global grain market and world grain stocks will be experiencing even greater fluctuations from year to year. In addition, there is a divergence in the policy approaches of different countries in the world in addressing climate change and the trend to use grain to produce biofuels cannot be reversed. All of these factors are increasing the pressure on the demand for grain, leaving little grain on the global market for China to import. Therefore, we cannot depend on the international market to safeguard China’s food security but must rely on our own resources. We must now be even stricter in carrying out the policy of the CPC Central Committee and the State Council forbidding the use of grain to produce biofuels. We must diligently adhere to all policies and measures to protect farmland, promote agricultural production, and encourage the cultivation of grain for some time to come in order to strengthen the foundation for China’s agricultural production and food security in response to climate change.

 We need to increase food stocks appropriately as a precautionary measure. In normal harvest years, the fluctuation in China’s grain production can be controlled to within 10% to 20% even in the face of extreme weather conditions. Global warming, however, could increase the uncertainty of damage due to extreme weather conditions in terms of time, affected areas, intensity, and duration. Extreme weather conditions are likely to seriously affect different major grain-producing areas at the same time and it is possible that severe droughts, rainstorms, and floods could strike adjacent areas and in successive years. China’s grain output may even fluctuate by as much as 30% to 50% due to uncertainty in the impact of climate change. If extreme weather conditions were to occur two or more successive years within a five-year period (i.e., if a drought were to last for two or three successive years for instance), the impact on economic and social development and people’s lives would be immeasurable. This kind of extreme weather pattern affected the entire country between 1928 and 1930 and again between 1959 through 1961. The first period occurred as China was experiencing the first warming period (1920s-1940s) of the last one hundred years. Therefore, we must not relax in good years or become overly concerned in lean years, instead always being prepared to cope with major disasters, large-scale disasters and long duration disasters. In addition to increasing state grain reserves, we need to scientifically regulate policies on grain purchases and reserves to adjust to changes in the climate and grain production to guard against shortages. 

 We need to pay close attention to monitoring and forecasting weather conditions and strengthen efforts to prevent damage to agriculture caused by adverse weather conditions as well as work to improve the ability of agriculture to adapt to climate change. We need to work hard to provide scientific and technological support for efforts to reduce grain losses caused by adverse weather conditions by carrying out more research on technologies used to monitor and forecast adverse weather conditions and prevent damage to agriculture caused by extreme weather conditions such as droughts, floods, storms, and low temperatures. We also need to carry out more research on long-term weather forecasting, forecasting of extreme weather events and assessment of the impact of extreme weather conditions on grain production. We need to set up a monitoring and warning system and regulation and service system for weather conditions affecting agriculture and set up a sound system for preventing and mitigating the damage caused by weather.

 We need to improve forecasting for weather conditions that favor agricultural diseases and insect pests and improve measures to prevent and control the damage caused by disease and insects. We need to carry out more research on the relationship between the occurrence and spread of crop diseases and insect pests on the one hand and weather conditions and climatic background on the other hand and on the impact of global warming on the occurrence and spread of crop diseases and insect pests so we can set up a forecasting and early warning meteorological index system for crop diseases and insect pests, focusing on providing of weather forecast services to predict years when crop diseases and insect pests will be heavy. We should systematically develop and plant drought-resistant, flood-resistant and high-temperature-resistant varieties and adopt technical measures to prevent and combat insect infestations in order to stabilize and increase production and prevent potential worsening of crop diseases and insect pests.

 We need to devote a great deal of effort to developing water-saving agriculture and follow a path of sustainable development of agriculture. China is a country with poor water resources. The rapid economic development of recent years has resulted in over consumption of water resources so that there is often not enough water to fill many reservoirs. China’s agricultural production largely depends on natural precipitation or overuse of groundwater. Water used in agriculture accounts for the overwhelming majority of total water consumption in some areas where water is in extremely short supply. According to an analysis of the current structure of water use, the most potential for reducing total water consumption is in agriculture. For this reason, the most urgent task in addressing the long-term threat to agricultural from adverse weather conditions is to adjust the pattern of cultivation, improve irrigation methods and develop water-saving agriculture. We must select and develop drought-resistant crop varieties and adopt measures such as straw mulching to reduce evaporation, minimum tillage, reduced tillage, deep tillage, soil improvement and chemical water-saving methods in arid and semi-arid areas and areas that are quickly becoming arid to reduce water consumption in agricultural production and in all sectors of society.

(From Qiushi in Chinese No. 23, 2009)


Note: Author: Director of the China Meteorological Administration 

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