Global warming a heated debate by ppi60054

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									                                         Global warming: a heated debate
Light from the sun is absorbed by Earth and converted to heat. Some of this heat travels back into space in the form of infrared
radiation. Certain gases in Earth’s atmosphere, such as carbon dioxide (CO2), trap some of this radiated heat, which warms the planet.
The heat-trapping gases, which function in a manner similar to the way glass does in a greenhouse, are called greenhouse gases.
Without the presence of greenhouse gases in the atmosphere, Earth’s temperature would be about 35°C lower than it is today, and
most life forms would probably not exist. Carbon dioxide is the most abundant green-house gas in the atmosphere, and as such it may
have the greatest impact on the amount of heat trapped. Methane and oxides of sulfur and nitrogen are far more efficient than CO2 in
trapping heat, but are much less abundant in the atmosphere. Since the pre-industrial era, atmospheric CO2 levels have risen 25
percent and continue to increase at a rate of 0.5 percent yearly. Some scientists project that this increase in CO2 could lead to a general
increase in world-wide temperatures ranging from 1.5°C to 4°C in the next 40 years.

Possible Effects of Global Warming
The Electric Power Research Institute
has warned, “The sweeping
consequences of accumulating
greenhouse gases in the atmosphere
may turn out to be the greatest
environmental problem of modern
times.” If the threat of global warming is
real, what kinds of changes can all life
on Earth expect? The warming would
affect the seas. The U.S.
Environmental Protection Agency
(EPA) predicts a sea-level rise of 0.3
meters in the next 40 years; 0.6 m to
1.8 m in the coming century. The total
rise within a few centuries might be as
great as 7.5 m. Part of this rise in sea
level would result from the melting of
the Antarctic ice sheet, and part of it
would be due to the increased volume
of the warmer water. The majority of
people in the United States live within
80 kilometers of a coastline, and many
of them would be affected by such a change. Eighty percent of coastal wetlands might also be covered by the sea, and destroyed as
wetland habitats. A rising sea that covers coastal estuaries could cause a drop in the populations of countless fish and shellfish
species. In the open seas, many species may become extinct as cold ocean temperatures rise and ocean currents are altered. These
changes could destroy fisheries, many of which are already on the verge of collapse due to over-fishing. Large-scale changes in major
land ecosystems could also result. One Canadian study showed that a 2°C change in climate temperature over 600 years could result
in a 30 percent loss of biomass in temperate forests. As the climate warms, ecosystems would shift northward. Forests could be
destroyed as trees become unable to adapt to new conditions or to expand their geographical range quickly enough. As the climate
becomes drier, the forested areas would be taken over by grass-lands. Many kinds of wildlife would likely be unable to migrate to
suitable habitats and could perish. Cold Arctic ecosystems could disappear completely if polar temperatures rise and Arctic ice melts.
Research conducted by the U.S. Department of Energy concludes that global warming “may yet overwhelm the life support system
crafted in nature over billions of years.” Many areas of North America, Europe, Africa, and Asia may experience a drastic change in
rainfall as a result of global warming. Major droughts could bring Dust Bowl conditions back to the Great Plains of the United States and
devastate the corn belt states of the Midwest. Agricultural production worldwide could fall drastically.

Evidence of Global Warming
Attempts are now being made to correlate warming of the climate in the past to increases in CO 2 in the ancient atmosphere. One area
of research involves analyzing the CO2 content of cores taken from huge polar ice sheets. European scientists found that during the last
160,000 years there has been a direct link between atmospheric CO2 levels and higher global temperatures. For years, scientists
predicted that plants and soils would absorb much of the extra CO2 that was being released into the atmosphere, because plants use
CO2 for photosynthesis. In fact, some studies had shown that plants would grow bigger and better because of the extra CO2. These
studies were based, however, on predictions of what would happen after global warming had fully taken place. More recent studies
have concentrated on the transitional period, before the full impact of warming sets in. The newer research demonstrates that in that
period, plants and soils will probably not be able to keep up with the increasing amounts of CO2 in the air. There is already direct
evidence that this view is correct. In the Arctic tundra, where spring snow melt is occurring earlier each year, plants and soil are actually
releasing more CO2, not absorbing more.

The Call to Reduce Fossil-Fuel Use
Some scientists urge that drastic measures be taken immediately to reduce or eliminate fossil-fuel consumption. Others are concerned
that if such measures are taken, the global economy could be devastated, at least in the short run. Still, many experts claim that the
short-term setbacks would be justified because, in their view, it would help avoid long-term, permanent climatic disaster. The American
Council for an Energy-Efficient Economy agrees that fossil-fuel use should be reduced. However, its members have a different view of
the economic results. Their data suggest that large reductions in fossil-fuel use could result in creation of about 1.1 million jobs by the
year 2010. They argue that as industries increase their energy efficiency, the money they save in lower energy costs could be invested
in new factories and equipment, resulting in new jobs.

Opposing Views on Global Warming
Although a large majority of scientists think that increasing levels of atmospheric green-house gases pose a serious threat, other
scientists do not agree. Some of them suggest that natural processes will prevent fuel emissions from causing disastrous changes in
world climate. They claim that other factors that will keep the planet cool may come into play. They point to the example of volcanic
eruptions, which spew tons of dust into the atmosphere. The dust prevents sunlight from penetrating the atmosphere, keeping the
climate cool. These scientists also refer to studies indicating that greenhouse gases may increase cloud cover in many regions. The
cloud cover would keep the sunlight out and temperatures cool. Critics of radical global-warming prevention say society cannot afford to
spend so much money to pre-vent a disaster that may not even happen. Some scientists opposed to drastic reductions of greenhouse
emissions also point to evidence that the climate of Earth naturally passes through cycles. For example, at the time fossil fuels began
forming millions of years ago, temperatures were quite a bit higher than they are today. It is possible, therefore, that the temperature
changes seen today could partially be the result of a natural cycle.

                                                                                                      The Problem of Prediction
                                                                                                      Some scientists argue that global
                                                                                                      warming cannot be predicted with
                                                                                                      confidence because forecasting
                                                                                                      climate far into the future is too
                                                                                                      complex. The current computer
                                                                                                      models used to predict global
                                                                                                      warming may not be able to
                                                                                                      incorporate and reflect all the
                                                                                                      aspects of climate patterns. The
                                                                                                      problem with using computer models
                                                                                                      is further complicated by another
fact. Computer models are like statistics in that they can be manipulated to support almost any desired out-come. Thus, scientists who
think that global warming poses a serious threat may be able to produce models that are tailored to demonstrate that point. Scientists
convinced that dangerous global warming is occurring argue that it is wrong to attack computer model data as nonscientific. They claim
that most data manipulation is being carried out by powerful groups, such as oil companies, who have an interest in showing that global
warming is not occurring. Concerned scientists also point out that predictions on climate can never be scientifically verified in the same
way as a simple laboratory experiment. It is impossible to put Earth into a test tube and carry out controlled climate experiments. These
scientists, along with many environmentalists, insist that their computer data are convincing and consistent. In their view, the
consequences of doing nothing and waiting to see what will happen may be too terrible to risk.

The Needs in Developing and Developed Countries
The possible effect of global warming on agriculture in developing countries would be disastrous, according to three independent
scientific studies. Global warming could result in drastic reductions of food production and increases in hunger in those countries. At the
1992 Earth Summit in Rio de Janeiro, Brazil, many nations ratified an agreement called the Global Warming Convention. This
agreement was designed to reduce greenhouse-gas emissions worldwide. Many developing countries were offended, however, by
some parts of the agreement. Greenhouse gases are produced by industries that bring wealth to a nation. The developing nations saw
the agreement as an attempt to slow their development by imposing strict standards on greenhouse emissions. These countries are
now demanding aid with emissions-control technology to help them raise their standard of living without adding to global warming.
Developing nations were also annoyed by the industrialized countries’ reluctance to reduce their own emissions drastically. W hat right,
asked the developing countries, do industrialized nations have to forbid citizens in a developing country to own cars or refrigerators
because those devices promote global warming? In addition, the U.S. has not participated or signed agreements such as the Kyoto
Protocol (convention on Climate change that began in 1997 to establish worldwide international treaties on global warming). A total of
154 countries have signed, The U.S. is one of the few countries that has not. The current administration claims that restrictions on
emissions would be disastrous for the American economy especially since this country is responsible for 20% to 25% of all CO2
emissions worldwide and we heavily depend on the use of fossil fuels. It is clear that the needs of all countries of the world will have to
be assessed before real progress can be made to diagnose and address the problem of global warming.
Name:______________________________________________                  Period: ______________________           Journal: _____________

1. Look at the first figure, define and describe what is meant by “global warming”. _________________________________________

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2. What are some possible environmental effects of global warming? ____________________________________________________

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3. Why do some countries oppose adoption of strict standards on fossil-fuel emission? _____________________________________

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4. Why do some scientists think it is difficult or impossible to predict the environmental effects of global warming? _________________

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5. Based on the bar graph, who contributes the most carbon dioxide emissions into the atmosphere? By how much? ______________

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6. Some states have begun to use revenues from drivers’ licenses, vehicle registrations, and highway tolls to pay for public mass-transit
systems. If you owned a car and drove a great deal, would you object to this policy? Why or why not?

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7. Describe the changes you might have to make in your life if the government ordered a sudden large reduction in use of fossil fuels
while developing alternative forms of energy. Describe the effects such a policy would have on our nation’s economy. Explain why you
would support or oppose such a policy.

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