How to understand the global energy balance and global warming? Please ask an expert friend who is familiar with geography to help answer.

Theme: the relationship between global energy balance and climate warming

abstract:

There are various forms of motion between the earth's surface and the atmosphere. Solar radiation is the main source of maintaining balance. Before reaching the earth, solar radiation will be weakened by the atmosphere, and finally it will absorb about 47% of solar radiation. Weather and climate depend on the balance between receiving solar radiation and losing heat. The global long-term average energy budget of the climate system should be balanced. Because all the energy that drives the climate system comes from the sun, energy balance means that the total amount of solar radiation entering the world must be equal to the sum of reflected solar radiation and infrared radiation emitted by the climate system. The disturbance of global radiation balance is called radiation forcing, which is caused by natural or human factors. Trace gases such as water vapor and carbon dioxide in the atmosphere, such as methane, ozone and freon, can make the short-wave radiation of the sun pass through almost without attenuation, but can absorb the long-wave radiation of the earth. Therefore, this gas has a similar greenhouse effect and is called "greenhouse gas". Greenhouse gases absorb long-wave radiation and reflect it back to the earth, thus reducing the net energy emission to outer space, and the atmosphere and the earth's surface will become hot, which is the "greenhouse effect". The "greenhouse effect" will cause sea level rise, affect agriculture and natural ecosystems, aggravate meteorological disasters such as floods and droughts, and affect human health.

Key words: energy balance, solar radiation, greenhouse effect and climate change

The temperature of the earth is determined by the rate at which solar radiation irradiates the surface of the earth and the rate at which the absorbed earth emits infrared radiation into space. In the long run, the energy absorbed by the earth from the sun must be in balance with the radiant energy emitted by the earth and the atmosphere. The radiation that reaches the ground after the solar radiation is weakened by the atmosphere is not divided into two parts: one part is the part that the sun directly projects to the ground, which is called direct radiation; But the part that reaches the ground after scattering, which is called scattered radiation. The sum of the two is the total radiation. Some scientific observations since the last century show that the concentration of various greenhouse gases in the atmosphere is increasing after the excessively strict radiation projected on the ground is partially absorbed and partially reflected by the ground. Before 1750, the carbon dioxide content in the atmosphere was basically maintained at 280ppm. After the industrial revolution, with the continuous growth of human activities, especially the consumption of fossil fuels (coal, oil, etc.). ) and the massive destruction of forest vegetation, greenhouse gases such as carbon dioxide emitted by human beings are increasing, and the content of carbon dioxide in the atmosphere is gradually increasing, rising by about 1.8 ppm (about 0.4%) every year, and has risen to nearly 360ppm so far. According to the measurement results, the increase of carbon dioxide in the atmosphere is about half of the man-made emission. The average temperature of the earth's surface depends entirely on the radiation balance, and greenhouse gases can absorb part of the thermal radiation from the surface, thus causing the global atmosphere to warm. In other words, these greenhouse gases are like a quilt covering the surface, and the surface of the quilt is colder than the inside and outside, so that the surface radiation will not be emitted into space unimpeded; So the surface is warmer than without these greenhouse gases. According to the assessment of the Intergovernmental Panel on Climate Change (IPCC), in the past century, the global average surface temperature rose by 0.3℃ to 0.6℃, and the global sea level rose by 10 to 25 cm. Many scholars predict that by the middle of the next century, if the world energy consumption pattern does not change fundamentally, the concentration of carbon dioxide in the atmosphere will reach 560ppm, and the average temperature of the earth will rise sharply. The Intergovernmental Panel on Climate Change issued a new assessment report in 1996, which once again affirmed that the increase of greenhouse gases will lead to global climate change. According to various computer models, if the concentration of carbon dioxide rises from 280ppm before the industrial revolution to 560ppm, the global average temperature may rise by 1.5℃ to 4℃.

Global warming will bring complex potential impacts on the earth and human beings, both positive and negative. For example, with the increase of temperature, sub-polar regions may be more suitable for human habitation; Under appropriate conditions, higher carbon dioxide concentration can promote photosynthesis, thus making plants have higher carbon fixation rate, leading to an increase in plant growth, that is, the yield-increasing effect of carbon dioxide, which is a positive impact of global warming. However, compared with the positive impact, the negative impact of global warming on human activities will be more enormous and far-reaching. In August this year, CCTV reported that the summit of Mount Qomolangma dropped by 1.3 meters due to climate warming.

1. Sea level rise

About13 of the world's population lives within 60 kilometers of the coastline, with developed economy and dense cities. The expansion of marine water bodies and the melting of polar ice and snow caused by global warming may raise the sea level by 50 cm in 2 100, endangering the global coastal areas, especially the densely populated and economically developed areas. These areas may be submerged or invaded by seawater, beaches and coasts will be eroded, land will be degraded, seawater intrusion and floods will be intensified, ports will be damaged, coastal aquaculture will be affected, and water supply and drainage systems will be destroyed.

2. Affect agriculture and natural ecosystems

With the increase of carbon dioxide concentration and climate warming, it may increase the photosynthesis of plants, prolong the growing season, and make some areas in the world more suitable for agricultural planting. However, the rapid changes in global temperature and rainfall patterns may also make agriculture and natural ecosystems in many parts of the world unable to adapt to this change or quickly adapt to it, which will have a huge destructive impact and cause extensive forest vegetation destruction and agricultural disasters.

3. Intensify meteorological disasters such as floods and droughts.

The increase of climate disasters caused by climate warming may be a more prominent problem. A slight increase in the global average temperature may bring frequent climate disasters-excessive rainfall, large-scale drought and continuous high temperature, resulting in large-scale disaster losses. According to the historical data of climate change, some scientists speculate that climate warming may destroy the ocean circulation, trigger a new ice age, and cause terrible climate disasters in high latitudes.

4. Affect human health

Climate warming may increase the risk of disease and mortality, and increase infectious diseases. High temperature will increase the burden of human circulatory system, and heat wave will lead to an increase in mortality. Malaria and other infectious diseases spread by insects are closely related to temperature. With the increase of temperature, malaria, lymphatic filariasis, schistosomiasis, leishmaniasis, dengue fever and encephalitis may increase or recur in many countries. At high latitudes, the risk of the spread of these diseases may be greater.