Why does the weather change, who caused it, who made it change,

The earth we live in is an extremely complex system, and the earth climate system is an important part of this earth system. In the long history of the earth, the climate is always changing. Generally speaking, the reasons can be divided into two categories: natural climate fluctuation and the influence of human activities. The former includes changes in solar radiation and volcanic eruptions. The latter includes the increase of greenhouse gas concentration in the atmosphere caused by human burning fossil fuels and deforestation, the change of sulfide aerosol concentration, land cover and land use. All the energy of the climate system basically comes from the sun. Therefore, the change of solar radiation is considered as the external cause of climate system change. At the end of 1970s, the application of satellite observation enabled human beings to accurately measure the changes of solar radiation output outside the atmosphere, only then did they know that the amount of solar radiation was not completely constant, especially during the abnormal activity of sunspots. Many scientists think that the more sunspots there are, the warmer the earth will be. The earth is cold in the middle of the night. However, the mechanism of solar radiation changes affecting climate is still unclear, and there is no strict theoretical or observational support. However, through research, scientists have found that the change of solar radiation and the change of the earth's orbit are not the main causes of modern global warming, and at the same time, they have basically ruled out the possibility that another natural factor affecting climate change-volcanic eruption is the main cause of global warming in the past century. In the natural change of climate system, the most important aspect is the change or pulsation of atmospheric and ocean circulation, which is the main reason for the change of climate elements at regional scale. Changes in atmospheric and ocean circulation can sometimes be accompanied by changes in landing surface. On the interannual time scale, El Nino, Southern Oscillation (ENSO) and NAO are important examples of atmospheric and ocean circulation changes. Their changes affect the weather and climate changes in a large range, even in the hemisphere or globally, and are the basis and basis for seasonal and interannual climate prediction at present. Many meteorologists in the world have been committed to this research for a long time, aiming at improving the global and regional climate prediction level. For a longer ten-year time scale, the Pacific interdecadal oscillation (PDO) and related interdecadal Pacific oscillation (IPO) can explain about half of the average change of global surface temperature, which is obviously related to regional temperature and precipitation changes. More and more studies show that human activities have an impact on climate change. In the past century, human activities have intensified the change process of the climate system. The latest authoritative report, Summary of Working Group I of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), points out that the correlation between human activities and climate change has reached 90% in the past 50 years. The study that human activities may increase the concentration of greenhouse gases in the atmosphere and may lead to climate change can be traced back to the end of 19. In 1896, Swedish scientist Svante algie and many other scientists have studied this problem one after another. 1957, Rivera and others published a paper in the United States on the possible climate change caused by the increase of greenhouse gas concentration in the atmosphere. In the same year, the Hawaii Observatory began to observe the concentration of carbon dioxide, which officially opened the prelude to human research on climate change. Emissions of greenhouse gases. What greenhouse gases will be produced? How do these greenhouse gases affect climate change? Human activities that emit greenhouse gases include: all fossil energy combustion activities emit carbon dioxide. Among fossil energy sources, coal has the highest carbon content, followed by oil and natural gas. Gas and natural gas leak during the exploitation of fossil energy, releasing carbon dioxide and methane; Industrial production processes such as cement, lime and chemical industry emit carbon dioxide; Methane is emitted by ruminants such as rice fields, cattle and sheep during digestion; Land use change reduces the absorption of carbon dioxide; Waste releases methane and nitrous oxide. There are six kinds of greenhouse gases produced by human activities mentioned above: in addition to carbon dioxide, greenhouse gases emitted by human activities include methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride. Carbon dioxide has the greatest impact on climate change. Once discharged into the atmosphere, it can last for up to 200 years, so it is the most concerned. These greenhouse gases are mainly caused by the greenhouse effect. Gases such as carbon dioxide in the atmosphere can penetrate the short-wave radiation of the sun (meaning less absorption), warming the earth's surface; However, it prevents the earth's surface from emitting long-wave radiation into space, thus warming the atmosphere. Because this effect of gases such as carbon dioxide is similar to the "greenhouse effect", it is called the "greenhouse effect". Before the industrial revolution, the "greenhouse effect" caused by gases such as carbon dioxide in the atmosphere made the average temperature of the earth's surface rise from-18℃ to 15℃ that today's natural ecosystems and human beings have adapted to. Once the concentration of greenhouse gases in the atmosphere continues to increase, it further blocks the long-wave radiation emitted by the earth into space. In order to maintain radiation balance, the ground will be heated to increase the amount of long-wave radiation. Water vapor will increase (increase the absorption of long-wave radiation on the ground by the atmosphere), snow and ice will melt (reduce the reflection of short-wave radiation on the ground), and the ground will be further warmed, that is, positive feedback will be formed, making global warming more significant.