How does the global temperature change?

Since 1 and 186 1, the global average surface temperature has fluctuated and increased. The two periods with the biggest increase in the 20th century were 19 10- 1945 and 1976-2000. 1998 is the warmest year. 2. Reasons: The massive emission of greenhouse gases hinders the normal heat dissipation of the earth: ① The global land precipitation has changed significantly. The precipitation in the middle and high latitudes of the northern hemisphere increases by 0.5%-2% on average every 10 year, increases by 0.2%-0.3% in the tropics and decreases by about 0.3% in the subtropics. (2) The area of snow and glaciers has decreased. Satellite data show that since the late 1960s, the global snow area has decreased by about 10%. Ground observation shows that alpine glaciers outside the polar regions generally retreated in the 20th century. ③ Global average sea level rise. Tidal data show that the global sea level rose by 0. 1-0.2m in the 20th century. The average sea level along the coast of Chinese mainland also showed an obvious upward trend, rising by about 0.14m in the past 100 years. ④ Global climate change itself is the change of resource conditions. For example, the increase or decrease of temperature and precipitation means the change of heat resources and water resources, which changes the spatial distribution pattern of water and heat resources and increases the difficulty for human beings to develop and utilize natural resources in many areas. ⑤ Global climate change intensifies natural disasters. For example, in the second half of the 20th century, the frequency of rainstorm in the middle and high latitudes increased by 2%-4%, while in some parts of Asia and Africa, the frequency and intensity of the ten-year drought in metals increased. ⑥ Global climate change will also lead to changes in the original ecosystem. According to relevant research, if the global warming trend is not effectively curbed, by 2 100, the habitat of animals and plants in the world13 will be fundamentally changed, which will lead to the extinction of a large number of species because it is difficult to adapt to the new living environment. ⑦ Global climate change has a more significant impact on major producing areas, such as agriculture, forestry, animal husbandry and fishery. As far as agriculture is concerned, climate change will have a certain impact on agricultural output, crop varieties, farming methods and the stability of agricultural production. (8) Climate change has expanded the epidemic of some diseases through extreme weather and climate events (El Ni? o, drought, floods, heat waves, etc.). ), harmful to human health.