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Global Warming activities from the Franklin Institute of Philadelphia

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Global Warming
Updated July 2, 2001

Have you heard that the world is warming up? Tell that to the people of Minnesota and Wisconsin -- last week a winter storm dumped seven inches of snow on them. Roads are frozen, schools are closed and nobody's throwing away sweaters.

But recent reports from a group of scientists brought together by the United Nations say it's true: over the next 100 years, the Earth's average surface temperature will increase by 3 to 10 degrees Fahrenheit. Day by day it's hard to tell if the temperature is really rising worldwide, so what are the scientists talking about? What's causing the increase, and who would mind if it got a little warmer anyway?

The problem, say the scientists, is that rising temperatures -- even slight rises -- could seriously disrupt current weather patterns, ecosystems and agriculture. And the data gathered from old temperature records, computer models, glaciers, and tree rings all point to a global warming trend. What's more, the scientists suspect that pollution from human activity is responsible for much of the warming.

Across the world, people burn fossil fuels, like coal and oil, for energy. The energy created provides electricity and heat for our homes and businesses, but the burning process, called combustion, also releases gases into the air. Some of the gases can trap heat near the Earth instead of letting it pass through the atmosphere into space. These gases are known as greenhouse gases because they reflect heat and warm the Earth the same way a greenhouse creates a warm environment for plants to grow, even in the middle of winter.

The most common greenhouse gas is carbon dioxide, which is an odorless, colorless and naturally occurring compound. It also spews from our power plants, factories and cars. It doesn't hurt us directly like pollution that can cause cancer. But the structure of its molecules creates the greenhouse effect, and the scientists say the effect is building up enough to warm the Earth.

The scientists who put together the U.N. report think the warming spells trouble. Even if we still have cold days and winters, an overall increase in average global temperature could change the Earth's environment as we now know it. As a worst-case scenario, some predict the polar ice caps will melt, raising sea levels and causing floods that spread disease and force millions of people from their homes.

Less dramatically, climate zones could shift. Some areas might become warmer and drier than they've been in the past. That could reduce water supplies and productivity on farms. An official in China said global warming could be responsible for the recent drought that cut China's grain harvest by 10 percent. Scientists warn that climate changes could lead to more frequent extreme weather in places people aren't used to it: very cold or hot spells; droughts or storms.

But while one cold snowstorm in Minnesota doesn't disprove global warming, it is also important to understand that on the other hand, out-of-the-ordinary hot days aren't enough to prove global warming is happening. Therefore, the U.N. report studies data spanning hundreds and thousands of years.

Looking at geological data, the scientists say it's likely the temperature increase in the 20th century was the largest of any century in the last 1,000 years. The 1990s were the warmest decade since the Civil War, and 1998 was the warmest year. The increase in temperature they're predicting for this century -- 3 to 10 degrees -- could turn out to be the fastest jump in 10,000 years.

While those numbers are dramatic, what does the U.N. report say about greenhouse gases and whether people are responsible for global warming? The scientists' report says there's "new and stronger evidence that most of the observed warming of the last 50 years is attributable to human activities."

Citing the burning of oil, gasoline and coal, scientists say the amount of carbon dioxide in the air has increased by 31 percent in the last 250 years and is at its highest level in 420,000 or even 20 million years.

But some scientists dispute the findings of the U.N. report. A few question whether data really shows the Earth is warming. Others argue there may not be a connection between burning fossil fuels and the warming trend. They debate whether human activity is really adding to the greenhouse effect and point to the Earth's long history of rising and falling average temperature and carbon dioxide levels.

During last year's campaign, President Bush voiced skepticism about whether humans are causing global warming, but he also suggested he might support reductions in carbon dioxide emissions from power plants.

Despite lingering debate over humans' responsibility for global warming, governments across the world have decided the problem may be real enough to do something about it. In recent years, conferences in Kyoto, Japan, and The Hague, Netherlands, have focused on ways for nations to reduce their greenhouse gas emissions.

The United States has refused to sign the Kyoto Treaty, but hasn't yet come up with an alternative plan to reduce harmful emissions. After a meeting with President Bush on June 29, the Japanese Prime Minister said his country will not sign without American support but will continue to work on finding solutions to the problem of global warming.

Politicians are working on an agreement to require industrialized nations to reduce their collective greenhouse gas emissions by five percent of 1990 levels. One issue in the policy debate is whether the carbon dioxide absorbed by forests can "count" as a reduction in pollution, especially since trees release carbon dioxide back into the air when they die.

The United States plays a major role in the global warming debate because it produces almost one-quarter of the world's greenhouse gases. On a per-person basis, Americans consume about five times more fossil fuel than the global average. Because of their relative wealth, Americans can afford many things that require a lot of energy to run. One example is the car. Although a popular way to travel, cars emit carbon dioxide as they burn gasoline. Sport utility vehicles (SUVs) are notorious for requiring a lot of gas.

Because of global warming, many activists think it's important for Americans and people worldwide to conserve energy better and find sources of power that pollute less. Some auto manufacturers are producing cars that use gas more efficiently. Engineers are improving ways to harness cleaner, renewable energy sources like wind and solar power.

Changing personal behavior may also be part of the global warming solution. For example, you can cut down on pollution by walking instead of using the car for short trips. The Sierra Club, Environmental Defense and the Environmental Protection Agency have more suggestions on ways to cut back on energy.

What do you think? Is it time to do something about global warming? What should governments and people do about the problem?