Feb 16, 2009

Changing concentrations of greenhouse gases

Although carbon dioxide is not the main component of the Earth's atmosphere, but its content remains constant change, and with climate change may have a great relationship. Scientists from the fossil carbon isotope content, suggesting the ancient earth's atmospheric carbon dioxide content. Figure 3-6 are the last 500 million years of carbon dioxide changes, the figure R = 1 is equivalent to the current atmospheric carbon dioxide content. In the early Cambrian period (more than 500 million years ago), carbon dioxide levels today are content 15-20 times, and then continued to decline until 3 million years ago, reached with the current content of a considerable extent. 100000000 ~ 2 millions of years ago, compared with the current content of 3 ~ 5 times Coincidentally, during this period (Jurassic) climate warming, the dinosaurs are the most advantage of the Earth's biological. 



 Figure 3-6 in the value of pushing the valuation, the former Soviet Union scientists in the Antarctic Vostok ice core is made of the ancient atmosphere containing actual samples, recorded over the past years changes in greenhouse gases. Figure 3-7 from the ice core are measured between the past 22 million years, carbon dioxide, methane content, as well as the estimated value of the temperature changes. We found that long-term changes in the three fairly consistent over the short-term change has some discrepancies. For example, 13-14 million years ago, the temperature higher than the modern climate 1-2 ℃, carbon dioxide and methane content is the highest. High levels of greenhouse gases, the greenhouse effect, and the temperature of natural increase. However, research has also pointed out that in high temperature environment, the soil biomass (biomass) faster rate of corruption, there will be more carbon dioxide released into the atmosphere from the surface; Moreover, if the marsh area increased, the surface release The methane emissions will also increase. Clearly, from Figure 3-7 can not determine the temperature and greenhouse gas content of the causal link between, but changes in the consistency of the two is no doubt. 



 Historical data from the above, we know that carbon dioxide content in the range of natural variation rather large (may be related to changes in the earth's crust, volcanic eruptions on the frequency). Since the European industrial revolution, mankind's industrial activities substantial use of fossil fuels (fossil fuel, such as coal, oil), to create a large amount of carbon dioxide, and emissions to the atmosphere. Before the industrial revolution, atmospheric carbon dioxide concentration has been maintained at about 280ppmv (that is, one million unit volume of gas contained in unit volume of carbon dioxide 280, Figure 3-8). After the Industrial Revolution, carbon dioxide levels increase rapidly after the 1950s, increasing faster rate until 1995 358ppmv. 



 Posterior lobe from the 18th century to 1994, carbon dioxide levels increased by 30%. These increases are mainly from the burning of fossil fuels, cement production and land use. Coal and oil in the combustion process of carbon is oxidized into carbon dioxide; limestone were used to produce cement process also release carbon dioxide; land development and utilization of not only reduced the amount of carbon dioxide absorbed by plants, but also to accelerate the perishable and produces carbon dioxide. We are now used in most of the Carboniferous coal (more than 300 million years ago) for some reason the trees were buried in the strata, and gradually formed the fossils. More than 300 million years ago plants absorb solar radiation energy left behind by modern human beings in one, two hundred years between the will of the exhausted. 



 Except carbon dioxide, methane, nitrous oxide, chlorofluorocarbons (CFC) and other greenhouse gases because the increase of population, economic activity becoming more active, and the rapid increase in Figure 3-9). For example, from before the Industrial Revolution to 1994, the methane content from 700ppbv (part per billion by volume, a billionth) to 1721ppbv; nitrous oxide from 275ppbv to 311ppbv. CFC for the man-made chemicals in the 1950s before the appearance of large numbers, and then increasing rapidly. Recently, as a result of Montreal Protocol banned CFCs, and their contents are no longer in the 1990s to increase.

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