What is Climate Change?
Climate change is a term for significant changes in the measures of climate – temperature, precipitation, even winds that lasts for several decades or longer. Remember that weather is the set of conditions that exist over relatively short periods, usually hours or days: thunderstorms, blizzards, or persistent heat waves. Climate is weather averaged over long periods of time – decades or longer.
Many students have heard of the “Greenhouse Effect.” Given our distance from the sun, Earth really ought to be much colder. Certain gases in Earth’s atmosphere – the layers of gases that make up the skies – hold onto the sun’s heat. As visible light from the sun passes through the atmosphere, it is absorbed by the Earth’s surface. Some of that energy is then emitted back to the atmosphere as heat. Greenhouse gases and water vapor absorb much of that heat, which would otherwise be released into space. The temperature of the atmosphere is raised and, subsequently, the temperatures on the Earth’s surface. The Greenhouse Effect makes our planet livable.
Human activities are now known to change the composition of Earth’s atmosphere. The build-up of carbon dioxide and a few other gases are a major concern to many scientists. These gases are emitted world-wide by automobiles, electrical plants, and even through clearing of forests and certain agricultural practices. Many scientists think that we are over-burdening the Earth’s ability to naturally cycle carbon.
Climate change may result from natural factors, such as changes in the sun’s intensity and slow changes in the earth’s axis rotation and orbit around the sun. Other natural processes within the climate system include changes in ocean circulation. But human activities are now linked to the current global trend toward warming temperatures.
The stand-out among these gases is carbon dioxide, or CO2. The influence of carbon dioxide is so high that it has become the standard used to measure the other greenhouse gases.
Some people still use the term, Global Warming. Most temperatures point to a general warming. But the term Climate Change is preferred because it better reflects what is at work. Some areas of the globe may actually experience cooler temperatures, precipitation patterns may be altered for some areas.
Teachers may find the Valuable Links page to be particularly helpful.