Amount of radiation

Human economic activities have created greenhouse gases and suspended particles, the former have a warming effect, while the latter have a cooling effect. Clearly, man-made greenhouse effect may be because the role of aerosol cooling effect, and has been underestimated. Greenhouse gases and suspended particulate characteristics quite different: 

 (A) produce the greenhouse effect greenhouse gases, aerosols have a cooling effect. 

 (B) of greenhouse gases have a long lifespan, suspended particles in a very short lifespan. 

 (C) the distribution of greenhouse gases are uniform, global, and the distribution of suspended particles is uneven regional. 

 This is because the characteristics of three different greenhouse gases and suspended particles are also very different from the impact. They are the direct effects of changes in the Earth's radiation balance. Scientists calculated the amount of radiation effect (radiative forcing) to assess their direct impact. The long term, without any abnormal interference (such as, air pollution, volcanic eruptions), the Earth's atmosphere should be in a state of radiation balance, that is, zero net radiation (radiation equivalent to the amount of radiation absorbed radiation doses). Once the imbalance in the Earth's atmospheric temperature is bound to increase (if the net amount of radiation is positive) or lower (if, by a negative net radiation), adjust to another until the temperature of the radiation balance. The role of the so-called radiation volume, refers to the atmospheric properties (such as, carbon dioxide content, cloud cover, etc.) change, the corresponding change in the volume of net radiation. 

 For global (or climate) change, we are most concerned about the troposphere / surface of this system are subject to the volume of radiation. Figure 3-12 are from before the Industrial Revolution to the present, as a result of greenhouse gases (CO2, CH4, N2O, CFC-11, CFC-12, Figure 3-12b), as well as man-made sulfate aerosol (Figure 3-12a) content changes caused by the volume of radiation. Figure 3-12c is to combine the two into the net after the amount of radiation. Radiation effects of greenhouse gases rather uniform distribution, but mostly in 2.5Wm-2 and between 1Wm-2. Its distribution by temperature, humidity and cloud cover distribution. For example, the value of low-latitude regions more than high latitudes, tropical ocean regions than the western half of the eastern half of the value of large desert areas (such as, sub-) has a relatively large value, and strong tropical convective region (such as, the Western Pacific , South America, Africa) is the value of small. 

 The role of suspended particles in the radiation level should be very uneven distribution, showing a high degree of regional. Maximum occurred in the eastern United States, Europe, East Asia, South America and South Africa, the West Bank, are man-made pollution in the region more serious. Other areas has not been significantly affected. Current estimates indicate that although the cooling effect of suspended particles can not be ignored, still less than the greenhouse effect greenhouse gases, so the net amount of radiation all over the world is still positive. The net amount of radiation the smallest regions, aerosol cooling effect is most obvious region. 

 IPCC scientists estimated from 1850 to 1990 between changes in atmospheric composition caused by the volume of radiation. Figure 3-13 in the global and annual average amount of radiation that they think are the best estimate value. Greenhouse gases for 2.45Wm-2, the error range of 15%. Which carbon dioxide is 1.56 Wm-2, methane 0.47 Wm-2, nitrous oxide 014 Wm-2, CFC-11 0.06 Wm-2, CFC-12 0.14 Wm-2, other gases 0.08 Wm-2. Suspended particles for the direct impact of -0.25 ~ -0.9 Wm-2, the indirect impact of 0 ~ -1.5 Wm-2, the two superimposed effect of -0.3 ~ -3 Wm-2. However, because the scientific community and its impact on the suspended particles is still very limited understanding, the estimated value of a large range of error. IPCC scientists pointed out that the role of suspended particles in the radiation volume estimates, the future may still have a substantial amendment. 

 In recent years, as a result of man-made CFCs damage the ozone, the stratospheric ozone decreased to reduce the absorption of short-wave radiation, stratospheric temperature decline. Colder stratosphere to the troposphere of the long-wave radiation volume also decreased, causing a negative role in the amount of radiation. On the other hand, more short-wave radiation penetrating the stratospheric ozone layer, atmospheric absorption for the troposphere, and its role in capacity coincided with the radiation. Scientists estimate the current negative effects of radiation is larger than the volume of radiation, the net effect of -0.1 ~ -0.2 Wm-2, but the estimated value of the error range considerably. At the same time, because of air pollution, tropospheric ozone has increased year by year with its greenhouse effect is caused by about 0.2 ~ 0.6 Wm-2 is the amount of radiation. During the same period, solar radiation intensity also slightly increased, which is equivalent to 0.3 Wm-2 is the amount of radiation. 

 Scientists do everything we can to explore the atmospheric composition change on the potential impact of climate change. In order to understand the mission first and foremost since the Industrial Revolution the role of the net amount of radiation changes. However, due to the lack of basic information, lack of understanding of a range of factors, scientists can only on the radiation effects of greenhouse gases have more confidence in estimates, changes in atmospheric composition to other estimates, the confidence is still not high.