Science World
Science World for grades 6–10 brings science to life with fascinating feature articles and hands-on activities that reinforce science concepts and help students build test-taking and critical-thinking skills.

Warming Signs

Scientists warn about the dangers of a changing climate.

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Earth's climate is changing, and according to scientists, kids your age will bear the brunt of the potentially damaging affects of a warmer world. By studying how the climate system works, experts can learn how climate may change in the future.

Since the Industrial Revolution, the modern world has gotten most of its energy from fossil fuels, or fuels like petroleum, coal, and natural gas, which are made of ancient decayed plants and animals. Burning of these fuels releases polluting byproducts including carbon dioxide gas into the air. These greenhouse gases trap heat in the atmosphere, causing the temperature of Earth's atmosphere to rise — a process called global warming.

"We don't know exactly what is going to happen due to climate change," says Ed Mathez, a geologist and curator of the exhibition Climate Change at the American Museum of Natural History in New York City. "The climate system is complex." Rather than have a wait-and-see attitude, Mathez feels it is better to prepare now for the potential negative consequences.

Dry Land

Scientists studying climate change are extremely concerned that some areas of the world will be hit by long and severe droughts. The American Southwest could even see decade-long dry spells, called "mega-droughts," says Mathez.

Scientists aren't sure of the exact relationship between global warming and mega-droughts. But they have noticed that global warming changes weather patterns. Researchers are still working to better understand the nature of this relationship.

Warming, as well as drought, causes soil, grasses, and trees to dry out, raising the risk of fire. In California, less rainfall over the past several years has caused more-frequent wildfires. Last year, more than 4,047 square kilometers (1 million acres) of land in California were destroyed by raging wildfires.

Wild Weather

During the summer of 2003, Europe experienced a heat wave unlike any other on record. As temperatures skyrocketed, approximately 35,000 people died.

"Events like these will become more frequent as global warming continues," says Mathez. The wacky weather will extend far beyond Europe's borders, and won't be limited to heat waves, either. For instance, according to Mathez, scientists are debating whether the Southeastern United States can expect to experience a greater number of hurricanes.

"What we are seeing is a greater number of severe storms," says Mathez. That's because with global warming more water evaporates from the ocean. This transfers heat from the ocean into the atmosphere. That heat fuels storms.

For example, since the 1970s, the number of tornadoes has risen by nearly 30 percent.

Changing Oceans

Rising levels of carbon dioxide in the atmosphere can cause trouble for ocean life. When carbon dioxide gas mixes with ocean water, it changes the composition of the water, says Mathez. The changing water chemistry can be harmful to animals with hard shells, such as the ones in corals that make up tropical reefs.

"If the coral reefs die out, the many hundreds of animals that rely on them for shelter and as a food source might disappear," says Mathez. For instance, the coral reefs in the Caribbean and in Australia's Great Barrier Reef are under threat.

Melting Ice, Rising Seas

As the atmosphere and oceans warm, giant masses of ice that sit on landmasses such as Greenland and Antarctica are melting. These continental ice sheets are literally crumbling into the sea.

The melting ice is slowly raising the level of the oceans. Each year, sea level rises by 2.6 millimeters (0.1 inches). Most experts believe this number will increase. They estimate that by the year 2100, sea levels will have risen by as much as 60 centimeters (24 inches). And this might be conservative, says Mathez, because projections fail to take into account that some of the ice on Greenland and Antarctica might have melted by then.

Rising sea level is expected to cause more frequent flooding of coastal areas due to storms. "This is potentially a very big problem, because two thirds of all cities are located on a coast," says Mathez. Within the next 100 years, scientists fear that low-lying areas will be more likely to flood, especially during severe storms. Coastal cities like New York City and London, England, are at risk.

"There are several possible solutions: People will have to move or build giant sea walls to hold back the seawater," says Mathez. "Or, we can work to minimize it now by reducing greenhouse gas emissions."

—Andrew Klein

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