The Greenhouse Effect and Global Warming
Recently, global warming has moved to a serious scientific issue. Because sunlight is constantly falling on the earth, the law of physics say that the planet has to radiate the same amount of energy back into space. Infrared radiation is sent out by the earth through the atmosphere, where molecules (carbon dioxide) hold outgoing radiation for a while, warming the surface.1 The molecules are kind of like glass in a greenhouse which is why this process of warming is called the greenhouse effect.
The greenhouse effect has been operating since the beginning of time. Without the effect, the surface of the earth would be -20 degrees Celsius, oceans would have frozen, and there would be no life on earth. The Washington Post has reported that the earth is warmer than it has been in 1,200 years.2 Recently, the summer of 1999 set records for heat in much of the United States. The average world temperature has increased one degree Fahrenheit over the last 120 years, making the world hotter than it has been in 100,000 years. From the beginning of the industrial revolution, concentrations of carbon dioxide have increased by 30%, concentrations of methane have doubled, and nitrous oxide has risen by 15%. The increases of these chemicals have enhanced the heat trapping capability of the atmosphere of the earth. Sulfate aerosols, cool the atmosphere because they reflect light back into space, but sulfates do not live long in the atmosphere.
Scientists still do not know what exactly is heating up the earth. Some say the earth is going through a natural cycle because the earth has gone through cold periods as well as hot periods. Mounting evidence is saying that humans are to blame for the rise in temperatures over the past 120 years. When we burn fossil fuel, oil, gasoline, and natural gas to run power plants, cars, and heat homes, we produce carbon dioxide. An increase in carbon dioxide magnifies the greenhouse effect. All this energy accounts for 80% of society’s carbon dioxide emissions, 25% of methane emissions, and 20% of nitrous oxide emissions. In 1994, the U.S. emitted one fifth of all the greenhouse gases in the earth. Carbon dioxide amounts are now 360 parts per million today, verses 315 per million parts in 1958, when modern technology started, and 270 per million parts in pre-industrial times. Scientists cannot actually predict what the climate will be like in the future, though. James E. Hansen, a director of NASA’s Goddard Institute for Space Studies, says that scientists know too little about the climate to make accurate predictions. "The forcings that drive long-term climate change are not known with an accuracy sufficient to define future climate change," Hansen wrote in a journal, The Proceedings of the National Academy of Sciences.
Many people believe that carbon dioxide is nothing to worry about. And many scientists are turning away from the debate about whether human-induced global warming is taking place. It is true that Earth’s ocean, plants, soil, and animals naturally release carbon dioxide into the atmosphere. And other gases such as methane and water vapor trap solar radiation like the way a greenhouse traps the sun’s warmth. Human activities are adding more carbon dioxide to the atmosphere than are being naturally recycled. This is what scientist believe is causing global warming.
And what are the effects of global warming? Rising temperatures are expected to raise the sea level and change local climate conditions. By changing these conditions, the climate could alter forests, water supplies, and crop yields. This could also threaten human health, and harm many ecosystems of animals. Deserts could expand into range lands and many National Parks could be altered. And many of the most important impacts depend upon whether rainfall will increase or decrease. The rate of climate change is also much...
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