Signs of climate change are everywhere. Nineteen of the planet's 20 hottest years on record took place in the 1980s or after. Rivers and lakes are thawing earlier each spring. Animals and plants are moving to higher elevations. The Arctic is heating up twice as fast as anyplace else in the world and polar bears are going hungry. Pacific islands such as Tuvalu are in danger of being swallowed by the sea and becoming a modern-day Atlantis. If people don't slash the amount of greenhouse gas emissions being pumped into the atmosphere , experts predict the planet's average temperatures could rise anywhere from 3 to 9 degrees Fahrenheit over the next century, with devastating results. According to the National Resources Defense Council (NRDC), "Sea levels will rise, flooding coastal areas. Heat waves will be more frequent and more intense. Droughts and wildfires will occur more often. Disease-carrying mosquitoes will expand their range. And species will be pushed to extinction."
Global warming will bring more extreme weather. Drought-prone areas will become drier and desertification will spread as higher temperatures squeeze more moisture from the soil. A 2007 United Nations Intergovernmental Panel on Climate Change report predicts that by 2020, between 75 and 250 million Africans will be vulnerable to water shortages caused by global warming. Additionally, as the world's glaciers-such as the Himalayas in Asia and the Andes in South America--melt more rapidly, the hundreds of millions of people who depend on the ice melt for drinking water, irrigation and electricity will be at risk.
Conversely, the world's wetter places will likely experience more precipitation. Delta regions in Bangladesh and India could see increased periods of intense rainfall and flooding, putting the livelihoods (often subsistence farming) and homes of millions of people in jeopardy. Scientists have predicted that sea levels could rise between 7 and 23 inches by 2100, seriously impacting island nations and low-lying coastal regions around the world. Additionally, warmer ocean temperatures could lead to more powerful and frequent storms. "Scientists have found that the destructive potential of hurricanes has greatly increased along with ocean temperature over the past 35 years," according to the NRDC.
In regions both warm and cold, animals and plants will be affected. Scientists have predicted that over a million species could become extinct by the middle of this century as climate change wreaks havoc on their habitats. Already, the Arctic's polar bears are in decline because melting ice has made it more difficult to reach food sources such as seals. In Costa Rica, the golden toad and harlequin frog have vanished completely due to global warming.
Climate change also poses a big threat to human health. Warmer temperatures could lead to an increase in heat exhaustion, respiratory problems and lung damage from higher concentrations of ground-level ozone, according to the U.S. Environmental Protection Agency (EPA). Higher temperatures will also put people at greater risk for certain infectious diseases, especially those that occur in warm regions and are transmitted by mosquitoes and other insects. "These 'vector-borne' diseases include malaria, dengue fever, yellow fever, and encephalitis. Also, algal blooms could occur more frequently as temperatures warm--particularly in areas with polluted waters-in which case diseases (such as cholera) that tend to accompany algal blooms could become more frequent," reports the EPA. Climate change could also negatively impact food and water supplies, which in turn would be detrimental to human health.
The United States represents approximately 5% of the Earth's population, but is responsible for 25% of the world's greenhouse gas emissions. The people most vulnerable to global warming are the citizens of the planet's poorest, less industrialized nations. They've contributed the least to climate change but are likely to suffer the most because they don't have the resources to adapt, like wealthier countries. According to a New York Times report, "The United States, where agriculture represents just 4 percent of the economy, can endure a climatic setback far more easily than a country like Malawi, where 90 percent of the population lives in rural areas and about 40 percent of the economy is driven by rain-fed agriculture