Name: Luo Shen
Student number: 29 1305 1 16.
Major: biochemistry and molecular biology
Grade: Grade 2009
Introduction Global climate change has greatly affected the living environment of human beings. In recent years, natural disasters such as tsunami, typhoon and earthquake have occurred continuously. In recent weeks, some big cities in China have also suffered from floods, and some time ago, most parts of China suffered from severe drought. This extreme climate has had a tremendous impact on human survival and people's lives, and the origin of these impacts is "climate change". Climate change also has a certain degree of impact on the land water cycle. Here, let's briefly describe the impact of climate change on the land water cycle.
Second, the influence of climate change on the function of terrestrial ecosystem in regulating terrestrial water cycle.
(1) Climate change Climate change refers to the change of the average climate state with time, that is, one or both of the average climate state and the deviation (anomaly) have statistically significant changes. The greater the deviation, the greater the extent of climate change and the more unstable the climate state [1]. Climate change is mainly manifested in three aspects: global warming, acid deposition and ozone depletion, among which global warming is the most urgent problem for human beings at present, which is related to the future of human beings! The climate change mentioned in this article is global warming by default. In the past 100 years, although the earth's temperature fluctuated, it generally rose by 0.5-0.6℃. The average surface temperature in the northern hemisphere rises by about 0.6-65438 0.4℃, which increases with latitude: 0-30 north latitude rises by about 0.4℃, 30-60 north latitude rises by about 65438 0℃, and 60-90 north latitude rises by about 2℃[2]. Climate change has a direct and indirect impact on the water cycle. The direct influence mainly comes from the temporal and spatial distribution of precipitation, the change of intensity and total amount, the migration of rain belt and the change of temperature, air humidity and wind speed caused by the change of atmospheric circulation. Indirect effects mainly come from land surface processes. Changes of land use, surface albedo, roughness, interfacial water vapor exchange and even soil hydrothermal characteristics. These potential factors are the result of the comprehensive influence of climate change and human activities, and at the same time have a feedback effect on the climate system. Therefore, climate change has caused changes in precipitation, soil water, evaporation, surface water and groundwater on different time and space scales. The terrestrial branches of the water cycle include precipitation, runoff in and out of the region, evaporation and changes in soil water content. Land water cycle is an important part of atmospheric circulation, which is not only dominated by atmospheric circulation, but also fed back to the atmosphere through water and energy exchange between land and air.
Table 1 Top Ten Disasters with the Most Victims in the World (1900-2008) [3]
Number of people affected by national disaster type and year
India Drought 1987.5 3.0
Drought in India
China flood 1998.7. 12.4
China flood1991.6.12.1
India Drought 1972 2.0
China flood 1996.6.30 1.5
China flood on June 23, 2003 1.5
Floods in India 1993.7.8 1.3
China flood1995.5.151.1
China flood in June, 2007151.1
(2) Changes in the global water cycle Due to the rising temperature and the expansion of irrigation scope, the evaporation on land increases. Especially in the middle and high latitudes of the northern hemisphere, the general warming of inland and ocean will lead to a significant increase in evaporation. In this way, the amount of clouds in the air in the temperate zone of high latitude increases, and the precipitation in this area also increases. In China, there are not only positive and negative correlation areas between global temperature change and precipitation change trend in China, but also their spatial distribution characteristics are quite clear. In the summer monsoon marginal areas from northwest China, Inner Mongolia to northeast China, that is, the areas west of the north central axis in the northern arid area, the precipitation increases synchronously at the end of global warming, and decreases synchronously when it gets cold. In the humid areas south and east of the semi-arid region, except the middle and lower reaches of the Yangtze River and the southeast coast, the precipitation in most areas decreases during global warming and increases during global cooling [4]. Hardy thinks that the global average annual precipitation will increase by more than 10%, but there are seasonal and regional differences [5]. With the global temperature rising and the water cycle accelerating, the global precipitation will increase in 2 1 century.
(C) Changes in the water cycle in China
1 The precipitation changes in Yunnan Plateau, and the warming near the mainland leads to the enhancement of land updraft. On the one hand, it leads to the enhancement of regional atmospheric circulation on the earth's surface, especially the airflow activity from the ocean to the land. The second is the change of water vapor condensation height and the landing over land. Yunnan Province, China, is affected by its geographical location and the complex topography of mountainous plateau, and the situation in Yunnan Province is also more complicated. Most parts of Yunnan Plateau have become rainy season, which is characterized by more clouds, higher humidity, shorter sunshine time and concentrated precipitation.
Table 2 Comparison of average precipitation length in Yunnan Province (according to Jindeshan, 2004)
Series deviation of multi-year average precipitation length of rainfall stations in administrative areas/%
1956- 1979 1956-2000
Kunming 44 928.6 856.7-0.9
Qujing 48 980.0 962.5- 1.8
Yuxi 32 95 1.8 942.4- 1.0
Zhaotong 36 942. 1 922.9-2.0
Chuxiong 35 909.2 904.4-0.5
Honghe 471233.31211.6-1.8
Wenshan 341141.61120.6-1.8
Simao 301923.71905.8-0.9
Banna131502.21472.1-2.0
Dali 30 827.2 8 17.2- 1.2
Baoshan 231410.01435.61.8
Dehong 201631.01680.03.0
Lijiang 27 892.8 907.3 1.6
Nujiang101134.91162.42.4
Diqing14 849.9 840.1-1.2
Lincang 361365.31372.00.5
As can be seen from the above table, the average annual precipitation in most areas of Yunnan Plateau has obviously decreased, while the precipitation in the western mountainous areas, which was originally rich in precipitation, has obviously increased in recent twenty years.
2 Response of Northwest Arid Area to Climate Change The arid area in Northwest China is located in the hinterland of the central part of Eurasia, which was originally a very typical temperate continental climate. The temperature difference between the year and the day is very large, and the precipitation is scarce. The climate differences between mountains and basins in this area and in the horizontal and vertical directions are also very obvious. The response of the region to global change is naturally one of the most concerned issues in the world. The average temperature in the northwest arid area is on the rise, and the average temperature increase rate in the northwest arid area in recent 50 years is 0.22℃/ 10a.
Table 3 Percentage/%of precipitation anomaly in different years in northwest arid area
All the year round, spring, summer, autumn and winter
1956- 1960 -7.8 2. 1 - 1.9 -5.5 3.7
196 1- 1970 -9.7 0.3 -6.9 -0.8 -3.2
197 1- 1980 -2.5 -4.2 - 1.9 5.7 0.3
198 1- 1990 6.4 3.2 - 1.5 -2.0 - 1. 1
199 1-2002 8.4 1. 1 7.0 -0.6 1.4
As can be seen from the above table, the annual precipitation in the arid area of northwest China has an obvious increasing trend. The change trend of precipitation in spring is not great, but it increases in summer, slightly in autumn and obviously in winter.
In the arid area of northwest China, except the runoff of Hexi inland river, other inland rivers are increasing. Climate change has obvious influence on runoff. For mountainous areas with precipitation as the main recharge source, runoff change mainly depends on precipitation change, followed by temperature rise. For mountainous areas where the melting of glacier snow is the main source of runoff, rising temperature will melt glacier snow in a short time and increase mountain runoff, but with the thinning and shrinking of glaciers and the disappearance of small glaciers, the regulation of glaciers on annual runoff will be weakened.
The influence of the Yangtze River basin on global warming caused by the increase of greenhouse gases is lagging behind and weak, and different regions have different regional responses. Since 1980s, the temperature in the middle and lower reaches of the Yangtze River has increased by 0.2-0.8℃, while the temperature in the upper reaches of the Yangtze River has decreased by about 0.2℃. The temperature rise of 0.8℃ in the Yangtze River basin mainly occurs in the Yangtze River Delta [6]. With global warming and the acceleration of water cycle, the precipitation in the Yangtze River basin has also changed. Since 195 1, the annual precipitation in the Yangtze River basin has shown a slight upward trend in the middle and lower reaches and a downward trend in the upper reaches.
Table 4 Variation Characteristics of Average Precipitation Anomaly in Yangtze River Basin in the Last 50 Years of 20th Century/mm
Year19501960197019801990.
Above Yichang 29.512.8-23.4-1.6-17.7
Above Hankou 22.317.9-15.9-8.6-9.5
The above Datong 34.13.8-16.9-12.2-1.6
The calculation and analysis of the evaporation of 20cm evaporating dish at various meteorological stations in the Yangtze River Basin in July 20001950 ~/KLOC-0 showed that the annual evaporation of the Yangtze River Basin showed a significant downward trend in the middle and lower reaches of the whole region, and the middle and lower reaches were the areas with the most significant downstream trend. During the flood season from May to September, the evaporation in all regions of the whole basin also showed a downward trend, but it was not obvious in the upper reaches. Judging from the seasonal evaporation trend, the evaporation season in the upper reaches has little change, and there is no obvious change trend in each season, while the change trend in the whole basin is consistent with that in the middle and lower reaches, with a downward trend in summer and autumn, especially in summer. The Yangtze River basin is rich in precipitation and runoff. The interannual variability is small, and the catchment area of the Yangtze River basin is large, so the interannual variability of runoff in the Yangtze River basin is also small.
Summarizing and forecasting the impact of global climate change on human beings is omni-directional, multi-scale and multi-level, which has great influence on the frequency and intensity of disasters and the ecological environment. For example, in recent years, major tsunamis and floods have occurred frequently all over the world, and China has suffered from droughts and floods in some provinces in the past six months. These events are closely related to the rainfall changes caused by global warming.
(1) In order to adapt to global climate change, we need to work on at least two key scientific issues: understanding the global environmental change we are facing. Global environmental change itself is a natural phenomenon, but there may be human driving force behind it; We should recognize the possible consequences of global environmental change and the possible ways to avoid risks.
(2) Facing the influence of climate change, countermeasures should be taken: implementing countermeasures to adapt to climate change and bringing climate change and its influence into social and economic development planning; Control the emission of greenhouse gases and reduce their content in the atmosphere; Strengthen the monitoring and research of climate change; Strengthen the protection of forests and vegetation and speed up the control of soil erosion in the basin; It is particularly important to pay attention to the publicity and education of climate change [8].
refer to
[1] Office of the National Coordination Group on Climate Change: Global temperature change-a challenge facing mankind. 17, Beijing, Commercial Press, 2004.
[2] Zheng Guoguang. Correctly understand and deal with global warming. China Environment Watch, 2007 (1)
[3] Hu Angang, Guan Qingyou. China's Response to Global Climate Change, Beijing: Tsinghua University Press, 2009:62.
, Ren Zhenqiu, Li. Influence of global temperature change on precipitation in China. Journal of Applied Meteorological Science,1994,5 (3): 333-339.
[5] Hardy J.T. Climate Change. England: John Wiley & Son Limited, 2003, 240.
[6] Sha, Shao, Huang Mei. Climate warming in China since 1980s and its impact on natural regional boundaries. China Science, 2002,32 (4): 317-326.
Su Boda, Jiang Tong, Shi Yafeng, et al. 1990 Analysis of Precipitation Trend in the Yangtze River Basin. Lake Science, 2003, 15 (Supplement): 38-48.
Yang Dayuan, Jiang Tong. Global Change and Regional Response, Beijing: Chemical Industry Press, 2005: 184- 185.