How to treat global warming
First, the impact of global warming on agriculture and forestry analysis
1. Global warming will obviously increase the effective accumulated temperature in all parts of China and prolong the frost-free period, which will be beneficial to the increase of multiple cropping index, and will also cause the northern boundary of warm crops to extend to high latitudes and the geographical displacement of crop producing areas. This means that the climate division of various crops in China may change at present: some suitable planting areas of crops will no longer be suitable, and some new suitable planting areas will appear. The agricultural layout of the whole country may undergo major changes. Moving the planting area northward is beneficial to the expansion of agricultural land, but most of the newly reclaimed land is difficult to obtain high yield because of poor soil or insufficient water resources. Crops moving northward are more vulnerable to sudden low temperature.
2. Global warming will gradually melt a large number of glaciers, leading to sea level rise. Since19th century, mountain glaciers around the world have almost retreated on a large scale. The snow data observed by NOAA satellite in the United States shows that the global snow area has decreased by 9% ~ 13% since 1980. Scientists of the British Antarctic expedition discovered through satellite observation that an ice shelf in Larsen was as big as Oxfordshire (about 2.
900 square kilometers of icebergs have separated from the Antarctic ice sheet and gradually flocked to the sea. With further global warming, icebergs melt and sea levels rise. For China, this may flood a large area of fertile lowlands along the southeast coast, hinder the discharge of surface water, raise the groundwater level and plunge a large area of land into swamps. Seawater intrusion in the Yangtze River and Pearl River Delta will salinize large areas of fertile land.
3. With the continuous warming of the global climate, the climate variability will inevitably change, and extreme climate will occur frequently. The research shows that there is often a nonlinear relationship between the change of the average value of climate elements and the change of the probability of extreme events (disasters): even if the average value of temperature and precipitation changes slightly, the frequency of disastrous weather may increase significantly. This means that the frequency of droughts, floods, typhoons and rainstorms will increase. In fact, since the 1990s, various natural disasters in China have never stopped: the catastrophic flood in 199 1 year once ravaged the land of Jianghuai; 1992- 1993 persistent drought swept the whole east; 1in the summer of 1994, there was persistent drought, high temperature and hot summer weather in central China, and severe floods in south China and northeast China. During the period of 1995, the middle and lower reaches of the Yangtze River and Liaohe Plain experienced another rare rainstorm and flood since the founding of the People's Republic. According to the figures released by China Meteorological Bureau, in 1994, 1 2 provinces, municipalities and autonomous regions in China affected an area of 50 million hectares, resulting in direct economic losses1.
70 billion yuan. Since the new century, all kinds of extreme weather have never stopped, especially in the winter of 20 10, snow disaster and extremely cold weather occurred in the north, and once-in-a-century drought occurred in five provinces in the southwest in spring, and the affected cultivated land area reached1.1100 million mu, 2.
210.2 million people have difficulty drinking water, and the drought lasted for nearly five months, and Yunnan alone lost10.7 billion yuan.
Due to global warming, the cold season will be shortened and the warm and hot season will be prolonged. This will improve the poor temperature conditions in some high latitudes to some extent; But for those mid-low latitudes that are already very hot in summer, it is undoubtedly a disaster of "adding fuel to the fire". High temperature will accelerate the growth process of crops, shorten the growth period, especially the filling period, and force crops to mature at high temperature. Extreme high temperature will significantly reduce the yield of wheat, corn, soybeans and other crops, and will also cause rice pollen abortion.
With the global warming, various diseases, insects and weeds of crops will be popular, surge and spread, and the occurrence range will also extend from the current low latitude to the high latitude. Climate warming will provide more favorable conditions for the growth, development and mass reproduction of various pests, so their wintering viability will be greatly improved, the number of female insects laying eggs will increase sharply, and the number of reproductive generations will also increase significantly. The increase of atmospheric CO2 concentration will also increase the C/N ratio of crop biomass, thus stimulating the appetite of insects. The change of atmospheric circulation provides external conditions for the large-scale spread of wind-borne pathogens.
6. After climate warming, the decomposition of soil organic matter will accelerate and the accumulation will decrease. If this continues, soil fertility will decline. In some areas where precipitation may increase, the increase of runoff will also aggravate the loss of soluble nutrients and topsoil on sloping land. In some areas where precipitation may drop sharply, vegetation will be reduced, topsoil will be easy to desertification, and cultivated land will be more vulnerable to wind erosion, which will produce a "sandstorm" effect once it encounters a storm; When washed by heavy rain, it will cause serious water erosion.
To sum up, global warming will have a far-reaching impact on human beings, especially agricultural production. This influence may have its advantages, but what is more worrying is its disadvantages. Therefore, how to seek advantages and avoid disadvantages, make use of its advantages, overcome its disadvantages, and seek countermeasures to adapt to or delay climate change is a brand-new topic before all mankind.