The panel found that the 1990s had been the warmest decade on record and predicted that temperatures will rise anywhere from 2. 5 to 10. degrees around the world over the next century, causing changes to global weather patterns. Indeed, unusual and frequently destructive weather had been occurring around the globe: twenty-seven inches of rain in one day in Hilo, Hawaii; an unheard-of thunderstorm in Barrow, Alaska; a huge ice storm in Atlanta, Georgia; massive floods in Europe; and an unprecedented high temperature of eighty-two degrees Fahrenheit in Iqaluit, a town in the Canadian Arctic.If these new weather patterns continue, the panel warned, the whole world could be facing a devastating environmental catastrophe resulting in massive floods, rising seas that wipe out coastal communities, rampant epidemics, millions of people left homeless, plant and animal extinctions on an unprecedented scale, and widespread starvation. What Causes Global Warming? Approximately two-thirds of the energy earth receives from the sun is absorbed by land masses and oceans and is then released into the atmosphere as warm, long-wave radiation.
The atmosphere of earth is full of so-called greenhouse gases such as water vapor, carbon dioxide, ozone, methane, and nitrous oxide that act like a blanket, trapping some of the heat radiating from the land and oceans and preventing too much energy from escaping into space. The gas blanket works in much the same way as the glass panels of a greenhouse, serving to trap energy and keep temperatures at a steady level. The trapped heat keeps earth at a comfortable average temperature of about sixty-three degrees Fahrenheit.This process is known as the greenhouse effect. Without the protection of the greenhouse gas blanket, life on earth would be difficult or impossible.
To illustrate the importance of the greenhouse effect, climate expert Mark Maslin compares earth with Mars and Venus. The atmosphere on Mars does not contain enough carbon dioxide to trap much solar energy, causing the average surface temperature of the planet to stay about 122 degrees Fahrenheit. Venus, on the other hand, has a much thicker atmosphere than earth, consisting of approximately 96 percent carbon ioxide. This massive greenhouse blanket results in a surface temperature of 860 degrees Fahrenheit. Maslin's example reveals that the precise combination of greenhouse gases in earth's atmosphere maintains a delicate balance that keeps the planet from getting too hot or too cold. What does the greenhouse effect have to do with global warming? According to the IPCC's 2001 report, human activities are causing an increase in the levels of greenhouse gases in the atmosphere.
An increase in greenhouse gases, particularly carbon dioxide, means more heat is being trapped by the atmosphere, leading to higher temperatures around the globe and the potential for global climate changes. Concentrations of atmospheric greenhouse gases have been steadily increasing since the beginning of the Industrial Revolution in the nineteenth century. The use of fossil fuels such as oil, gas, and coal has increased carbon dioxide levels by 30 percent. Fossil fuel use, waste dumps, increased agricultural production, and massive livestock operations have increased levels of methane by 240 percent.Modern industries such as aluminum production and the use of liquid coolants such as those in air conditioners have added new gases including perfluoromethane and chlorofluorocarbons (CFCs) to the greenhouse blanket. Because of the increased concentrations of greenhouse gases, states Maslin, "planet Earth is warming faster than at any other time in the past 1000 years and there is little doubt that human activity is to blame.
" The Debate over Global Warming Experts disagree about the causes of global warming, its severity, and how best to solve the problem.Kevin A. Shapiro, a neuroscience researcher based at Harvard, while acknowledging that earth's climate has warmed slightly in the last century, argues that this fact "more or less exhausts the scientific consensus. On every other important question--what the major causes of global warming are, what its effects will be, whether we should try to prevent it and, if so, how--there is considerable uncertainty.
" The use of computer simulations of weather patterns to predict the future extent and impact of global warming is particularly divisive.According to Shapiro, the use of these models has resulted in the accumulation of patchy and unreliable conclusions about human impact on earth's climate. Even the 2001 IPCC report, which was written by 122 lead authors and 515 contributing authors and was reviewed by another 450 scientists, does not represent total agreement among climate experts about the causes and effects of global warming. Meterologist Richard Lindzen, who was one of the 450 scientists who contributed to the report, notes that the "summary for policymakers" that is widely quoted in the media was written by only 14 of those 450 scientists--hardly a consensus.In an article about Lindzen and his views, Newsweek reporter Fred Guterl states that "many scientists agree that the IPCC, in its zeal to build the case for doing something about global warming, plays fast and loose with the science, glossing over uncertainty and pushing its conclusions too far.
" Earth Is Getting Warmer Although there is still some dispute about the effect human activities have on global warming and what is ultimately causing global climate change, the experts agree that, whatever the cause, earth is, indeed, getting warmer.Many climate scientists believe that allowing global warming to continue unchecked will have devastating consequences for Earth. Alexander E. MacDonald, a scientist with the National Oceanic and Atmospheric Administration, warns that warming temperatures could lead to devastating changes in weather patterns on a regional level. MacDonald predicts that summers may become much drier in the mid-continents of North America and Eurasia, with the potential to devastate some of the earth's most productive agricultural areas.
The Arctic ice cap may disappear, a profound blow to a unique and fragile ecosystem. The Atlantic Ocean currents that warm Europe maybe disrupted. The West Antarctic Ice Sheet may collapse, leading to a rise in sea levels around the world. Rising sea levels pose a threat to low-lying islands that could disappear completely under rising water. Warmer, drier summers in the world's most productive agricultural regions could devastate crop yields.
Melting ice in the Arctic will endanger the habitat and food supply of animals such as polar bears.According to many experts on climate change famine, disease, and warfare could ultimately become widespread as water and other resources become scarce or disappear. As John T. Hardy, chair of the Department of Environmental Sciences at Western Washington University, states, there is no longer any doubt that "unprecedented changes in climate are taking place. If we continue on our present course, life on Earth will be inextricably altered. The very sustainability of the Earth's life-support system is now in question.
Not all scientists believe that the potential consequences of global warming will be so dire. Some predict that warmer temperatures will lead to increased crop yields, healthier forests, and an improved quality of life. In an interview for U. S. News & World Report, climatologist Craig Idso remarked that the extra carbon dioxide in the atmosphere "is going to be nothing but a boon for the biosphere.
Plants will grow like gangbusters. " Shapiro points out that early predictions about the consequences of global warming have not yet come to pass.In the 1980s, he relates, climatologists predicted that sea levels would rise twenty-five feet over the next century. "Under the worst-case scenario now envisioned by the IPCC," Shapiro states, "the oceans should rise no more than a foot over the next century, not nearly enough to pose a major threat. " The Danger of Stopping Global Warming Some researchers believe that the consequences of attempting to slow global warming may be worse than the impact of the warming itself. Attempts to control greenhouse gas emissions could end up hurting the world's economy.
Indur M. Goklany of the Political Economy Research Center in Bozeman, Montana, writes that attempts to slow greenhouse gas emissions over the next several decades "could indirectly aggravate hunger and reduce public health services, either of which, separately or together, could increase mortality, particularly in developing countries. " Goklany argues that there is no guarantee that controlling greenhouse gases "will provide net global benefits for public health or, separately, for the environment, but there is a good likelihood that it may well worsen both. For Goklany and other scientists who believe that global warming is not a serious problem, the best solution may be to do nothing. Although most climate experts agree that global warming is occurring, no consensus has yet been reached on the scope and consequences of climate change. Contemporary Issues Companion: Global Warming provides various perspectives on this critical issue, including discussions of the research and science of global warming, the possible consequences of unchecked global warming, and potential solutions.
