Global warming is the long-term, cumulative effect that greenhouse gases, primarily carbon dioxide and methane, have on Earth's temperature when they build up in the atmosphere and trap the sun's heat. It's also a hotly debated topic. Some wonder if it's really happening and, if it's real, is it the fault of human actions, natural causes or both?
When we talk about global warming, we're not talking about how this summer's temperatures were hotter than last year's. Instead, we're talking about climate change, changes that happen to our environment, atmosphere and weather over time. Think decades, not seasons. The term global warming itself is a bit deceptive because it implies we should expect things to get hotter -- not necessarily stormier, drier and even, in some instances, colder. Climate change impacts the hydrology and biology of the planet -- everything, including winds, rains and temperature, is linked. Scientists have ob served that the Earth's climate has a long history of variability, from the cold climes of the Ice Age to temperatures as hot as an Easy-Bake oven. These changes are sometimes noted over a few decades and sometimes stretch over thousands of years. What can we expect from a planet undergoing climate changes?
Scientists studying our climate have been able to observe and measure changes happening around us. For example, mountain glaciers are smaller now than they were 150 years ago, and in the last 100 years, the average global temperature has increased by roughly 1.4 degrees F (0.8 degrees C) [source: EPA]. Computer modeling allows scientists to predict what could happen if the climate pattern continues on its current course, projecting, for instance, that temperatures could rise an average of 2 to 11.5 degrees F (1.1 to 6.4 degrees C) by the end of the 21st century [source: EPA].
In this article, we'll look at 10 of the worst effects of climate change, including some immediate effects observed and some hypothesized through climate modeling.