What Are Gas Emissions?
Greenhouse gas emissions cause the greenhouse effect and increase global temperatures. While the earth absorbs solar radiation, it also radiates heat to outer space, and its thermal radiation is mainly 3 to 30 m long-wave infrared. When such long-wave radiation enters the atmosphere, it is easily absorbed by some gas molecules with large molecular weight and strong polarity. Due to the low energy of infrared, it is not enough to cause the breaking of molecular bond energy, so no chemical reaction occurs after the gas molecules absorb the infrared radiation, but just block the heat from escaping from the earth. The role of the "greenhouse". The absorption of long-wave radiation from the earth by certain trace components in the atmosphere keeps the heat near the ground, which causes the global temperature to rise. This is called the greenhouse effect.
Due to human activity or natural formation
The trace components of the atmosphere that cause the greenhouse effect are called greenhouse gases. H 2 O and CO 2 already present in the atmosphere are natural greenhouse gases. It is under their action that the most suitable environmental temperature for the earth's organisms is formed, so that life can survive and reproduce on the earth. Without the atmosphere and these natural greenhouse gases, the surface temperature of the earth will be lower than now , human beings and most animals and plants will face a crisis of survival. The main cause of global warming is due to the excessive use of energy and the overexploitation of natural resources by human beings in their own development processes, which has caused the concentration of greenhouse gases in the atmosphere to increase at an extremely rapid rate. These greenhouse gases include carbon dioxide, methane, nitrous oxide (N 2 O), hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. Table 1 shows the impact of human activities on some greenhouse gas changes.
Table 1 Impact of human activities on changes in some greenhouse gases
| project | CO 2 | CH 4 | N 2 O | CFC-11 | HCFC-22 |
| Volume fraction in 1994 | 358 × 10 -6 | 1720 × 10 -9 | 312 × 10 -9 | 268 × 10 -12 | 72 × 10 -12 |
| Concentration growth rate (% / a) | 0.4 | 0.6 | 0.25 | 0 | 5 |
| Atmospheric life (a) | 50 200 | 12 | 120 | 50 | 12 |
The growth rates of CO 2 , CH 4 and N 2 O are calculated on the basis of 1984, while CFC-11 and HCFC-22 are calculated on the basis of 1990. [1]
Global warming has become an important obstacle to the sustainable development of human economy and society. Controlling pollutants and greenhouse gas emissions is something we need to attach great importance to. The success of the Olympic venues in energy conservation and emission reduction has given us great confidence. As long as we attach great importance to the development of new energy sources that replace coal power, it is feasible in theory and practice. In 2005, China's power generation exceeded 500 million kWh. However, 80% of China's power generation is dominated by coal. It is not difficult to see from the status quo of China's energy utilization that the rising temperature of the earth is "burned" by human coals. Therefore, it is the last word to reduce carbon dioxide emissions and reduce the use of non-renewable resources such as coal and natural gas. To this end, new energy sources, such as solar energy, wind energy, biomass energy, hydrogen energy, tidal energy, and hydropower (small hydropower), should be fully developed and utilized to block greenhouse gases at their source. Let's look at an example of biomass energy utilization. In January 2008, the world's largest Mengniu Biomass Biogas Power Plant formally connected to the national power grid in Hohhot. This biomass energy power plant with a total investment of 45 million yuan uses methane gas produced by anaerobic fermentation of cattle manure on the farm. The composition of methane and natural gas is basically the same.
CO 2 contributes 60% to the greenhouse effect. From 1750 to 1994, the volume fraction of CO 2 in the atmosphere has increased from 2.80 × 10 -4 (280ppm) to 3.58 × 10 -4 (358ppm), and in 2000 it reached 3.68 × 10 -4 (368ppm). Since the life of CO 2 in the atmosphere is as long as 50 to 200 years , even if CO 2 emissions can be maintained at current levels, its concentration will still double in the 22nd century. If humans do not take effective control measures for CO 2 emissions, it is predicted that in the next 100 years, global temperatures will increase by 1.4 to 5.8 ° C and sea levels will continue to rise by 88 cm. Therefore, the "United Nations Framework Convention on Climate Change" Kyoto Protocol adopted in 1997 requires: Six greenhouse gas emissions from developed countries be reduced by 5.2% compared with 1990; between 2008 and 2012, compared with 1990, the European Union The average reduction is 8%, the United States reduces 7%, Japan and Canada reduce 6%, Eastern European countries reduce 5% to 8%, New Zealand, Russia, Ukraine 0%, Australia 8%, Iceland 10%. As a developing country, the "Kyoto Protocol" does not impose obligations on China to reduce greenhouse gas emissions.
Among the six greenhouse gases, CO 2 is the highest in the atmosphere, so it has become the focus of reduction and control. However, the effects of several other greenhouse gases cannot be underestimated. To assess the relative ability of various greenhouse gases to influence climate change, a parameter called the "global warming potential" (GWP) was used.
Table 2 Potential global warming trends of greenhouse gases
| kind | Atmospheric life (a) | GWP (time scale) |
| 20a | 100a | 500a |
| CO 2 | variable | 1 | 1 | 1 |
| CH 4 | 12 ± 3 | 56 | twenty one | 6.5 |
| N 2 O | 120 | 280 | 310 | 170 |
| CHF 3 | 264 | 9100 | 11700 | 9800 |
| HFC-152a | 1.5 | 460 | 140 | 42 |
| HFC-143a | 48.3 | 5000 | 3800 | 1400 |
| SF 6 | 3200 | 16300 | 23900 | 3490 |
The so-called "radiative forcing" refers to the change in the top tropospheric net radiation flux (unit: W / m 2 ) caused by changes in the atmosphere (such as greenhouse gas concentrations, aerosol levels, etc.). If there is radiative forcing, the earth-atmosphere system will reach a new energy balance by adjusting the temperature, which will cause the temperature of the earth to rise or fall. Table 2 lists the potential global warming trends for some greenhouse gases. [1]
The World Bank released a report that global carbon dioxide emissions in 2003 were 16% higher than in 1990. In 1960, low- and middle-income countries accounted for only one-third of the world s emissions, and now China s total emissions increased by 73% between 1990 and 2003 The total emissions of India increased by 88%, the total emissions of the United States and Japan increased by 20% and 15%, and the total emissions of EU countries increased by only 3%. Therefore, emissions are mainly from industrialized countries and fast developing countries. In China and India, fossil fuels account for 66% of the world's electricity generation; in the Middle East, fossil fuels account for 93%, East and South Asia account for 82%, and Latin America And the Caribbean account for 38%.
In developing countries, greenhouse gases also mainly come from agriculture and land use and deforestation. The World Bank and the British government released a report in 2007. Deforestation has made Indonesia the third largest emitter in the world after the United States and China. From 1990 to 2005, nearly 45,000 square kilometers of deforestation were recorded in low-income countries.
A research report released by the American Academy of Sciences in late 2007 showed that the increase rate of world carbon dioxide emissions from 2000 to 2004 was almost three times that of the 1990s. The increase rate is mainly due to the increase in the capacity density of economic activities and the increase in the carbon density of the capacity system. At the same time, due to the increase in population, the increase in per capita DDP is also one of the reasons for this problem. From 2000 to 2004, developing countries accounted for about 40% of total emissions. 73% of global emissions growth in 2004 came from developing countries and a few advanced economies. The above accounted for 80% of the world's population. In the same year, developed countries accounted for total emissions. The amount is about 60%, and these countries have accounted for 77% of accumulated emissions since the Industrial Revolution.
