Climate Change

Many news accounts today would lead people to believe that climate change is a new phenomenon. In reality, however, the Earth's climate has changed constantly throughout the history of the planet, long before humans existed.

In fact, Earth has one of the liveliest and most changeable climates of any planet in our solar system, swinging from long periods of warmth through equally long ice ages. The difference is that today, the effects of humans on the planet appears to be accelerating the natural forces of climate change, posing a serious threat of exterminating not only endangered animal and plant species, but the human species as well.

Throughout earth's geological history, natural events have affected the climate such as enormous volcanic eruptions. The famous explosion of the Indonesian volcano Krakatau in the 19th century spewed out so much ash and sulfur dioxide into the atmosphere that the Earth's global climate was cooled for three consecutive years. Beginning in the late 18th century, the effects of the Industrial Revolution changed the composition of the atmosphere through burning coal and other fossil fuels. While there are those who doubt that humans are affect the global climate, scientific observations have clearly documented changes that are traced directly to human activities such as deforestation, industrial output and waste disposal.



According to the U.S. National Academy of Sciences, "climate change' is the term preferred over "global warming," because it is more inclusive of other changes besides increases in temperatures. These additional changes include such climate measures as precipitation and wind that last for decades or longer. Changes in climate may be caused by:

•Natural changes such as increases or decreases in the Sun's intensity or shifts in the Earth's orbit;

•Changes in natural processes such as shifts in ocean currents;

•Human activities that affect the composition of the atmosphere and the land, such as emissions from fossil fuel use, deforestation, desertification and urbanization.

Over the past 210 years, the concentrations of what's known as "greenhouse gases" have increased significantly. These gases have resulted from humans using coal and oil for energy, and cutting down forests for fuel, agriculture and urbanization. These gases, such as carbon dioxide, act on the Earth's atmosphere like the glass panes of a greenhouse (hence the name). They prevent excess heat from escaping into space, keeping it trapped in the planet's atmosphere and warming the surface.

While this effect has been beneficial to life on Earth, surface temperatures are now climbing above levels conducive to current biological life. According to date from the U.S. National Oceanographic and Atmospheric Administration (NOAA) and the U.S. National Aeronautics and Space Administration (NASA), the average surface temperature has risen by nearly 1.4 degrees over the past century. The eight warmest years recorded since 1850 have occurred since 1998; 2005 was the warmest year. Climate models now predict that if greenhouse gases continue to increase, Earth' average surface temperature could rise between 3.2 and 7.2 degrees by the end of the 21st century.

However, scientists aren't sure how fast temperatures might rise or how these higher temperatures will change the planet. All that's known for sure at this point is that human activities seem to play a major role in these changes, and that humans must adapt their processes of civilization in order to prevent what could be severe changes that could threaten the continued existence of all biological life.