Scientists warn about the dangers of a changing climate.
The world's climate is changing. Scientists say the effects of these changes could be devastating to living things on Earth — including humans. It's likely that people your age will see these effects firsthand. But your generation may also help find solutions to the problems.
Scientists say that one of the biggest causes of climate change is the rising level of carbon dioxide gas in the air. Many power plants, factories, and cars run on fossil fuels like oil. Burning these fuels releases carbon dioxide gas into the air. This gas traps heat in the atmosphere, causing Earth's climate to warm. That process is known as 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 upcoming exhibition Climate Change, at the American Museum of Natural History in New York City. The processes that control Earth's climate are complicated, and scientists don't know how the amount of carbon dioxide in the atmosphere will change over time. Despite this uncertainty, researchers are trying to tackle the problem of climate change head-on. "It is better to prepare now for the potential negative consequences," says Mathez.
Global warming may result in potentially deadly changes to the world's weather. During the summer of 2003, approximately 35,000 people died when Europe experienced an extreme heat wave. "Events like this will become more frequent as global warming intensifies," says Mathez.
Scientists say that global warming could also cause more severe storms, such as the tornadoes that strike the Midwest each year. With global warming, more water evaporates from the oceans. This process transfers heat from the oceans into the atmosphere. That additional heat fuels more storms. "We already can see a greater number of storms," says Mathez.
While storms are expected to slam some areas of the world, scientists are also concerned that global warming will cause other areas to experience long and severe droughts. Mathez says that places like the Southwestern United States could even see decade-long dry spells, called "mega-droughts."
Scientists aren't sure about the exact relationship between climate change and drought. But they suspect that global warming changes weather patterns, affecting the amount of rainfall.
Over the past several years, drought in California has caused soil, grasses, and trees to dry out. That has resulted in more frequent wildfires. In 2007, more than 4,047 square kilometers (1,000,000 acres) of land in California were destroyed by raging wildfires.
Scientists are concerned that the rising levels of carbon dioxide gas in the atmosphere will also cause trouble for ocean life. When carbon dioxide gas mixes with ocean water, it changes the composition of the water. The changing water chemistry can be harmful to animals with hard shells, such as corals. The coral animals that create tropical reefs are dying in places like the Gulf of Mexico.
"If the reefs die out, the many hundreds of animals that rely on them for shelter and as a food source might disappear," says Mathez.
As the atmosphere and oceans warm, giant sheets of ice that cover land in Antarctica and Greenland are melting. Chunks of ice are sliding off the land and falling into the oceans.
One result of the melting ice is a rise in the level of the oceans. Scientists don't know by how much sea level will rise. But scientists fear that in the next 100 years, low-lying areas will be more likely to flood, especially during storms. Cities located on coasts, like New York City, London, and Shanghai, China, are all at risk for flooding. "If people want to continue to live in these cities, we may have to build giant seawalls to hold back the seawater," says Mathez.