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Sunday, September 17, 2006

It’s Getting Hot Out There – Or Is It?

Image by D L Ennis

Article by Dave Perault

You’ve heard the buzz words: greenhouse effect, climate change, global warming, sea level rise. As the heat of summer approaches, you’ll hear them even more. These topics underlie one of the most controversial environmental debates today, with even scientists arguing back and forth, and politicians unable to take a stand. Here, we’ll review the facts, discuss the fiction, and dispel the myths. Although the relevance of this debate is not limited to the Blue Ridge Mountains, its implications may certainly affect both the environment of this region and those that live within it.

First, the greenhouse effect is a real and natural phenomenon (although a bit of a misnomer as a true greenhouse actually functions slightly differently – but that’s another story). Without it, our planet would be too cool to sustain life as we know it. The mechanism underlying the greenhouse effect is actually quite simple. The sun emits shortwave radiation in the form of light. This light passes through our atmosphere and strikes the planet’s surface. The surface then absorbs this radiation and re-radiates it in the form of longwave radiation or heat (if you’ve ever walked barefoot along a beach during a sunny day, you’ve experienced this). Finally, due to the structure of some atmospheric gases such as carbon dioxide, water vapor, and methane, this longwave radiation is unable to completely pass back through the atmosphere and is trapped, in turn warming our planet. This process is well understood and accepted by all scientists.

Next we hit the dicey stuff, beginning with climate change and global warming. Throughout history, the earth’s average temperature has fluctuated – even well before it could have been impacted by humans. These fluctuations are mostly attributed to natural changes in the earth’s orbit and fluctuations in the composition of atmospheric gases. During cooler periods, the Appalachians were much different, with glaciers extending down into the eastern U.S., and boreal climates found even on our southern mountains. Curretnly, most scientists agree that average temperatures are on the rise, and have been for over 100 years.

Now things begin to get murky as we arrive at the big question: Are human activities responsible for the recent rise in temperatures? On one hand is the established relationship between greenhouse gasses and warming, and the fact that humans are dramatically increasing the amount of such gases in our atmosphere. Deforestation increases carbon dioxide, agriculture (think cows) and landfills (think decomposition) increase methane, and the use of fossil fuels (think cars and coal-burning power plants) is especially problematic. On the other hand, however, are the arguments that the recent temperature changes are simply part of the natural cycle, that the earth will correct itself (for example, with the oceans absorbing excess heat) and that increasing greenhouse gases could push temperatures either direction (think how clouds warm a winter night by blanketing in heat, but also cool a summer day by blocking out sunlight). While most scientists do believe that human activities are simply too much to not attribute part, if not much of the blame to, there are some well-respected experts who disagree.

Let’s move away from the above debate, and ask ourselves: If the planet is warming, does it really matter? Simply predicting hotter days is not the answer as many of our planet’s processes are tied in to its heat budget. Precipitation, extreme weather, plant growth, and sea levels are just a few that may be affected. The key is understanding where these impacts may occur and to what extent. Glaciers are indeed currently retreating, polar ice caps are shrinking, hurricanes are increasing and becoming more violent (at least for 2005!), oceans appear to be rising, and droughts seem to be more common. Even human health may ultimately be affected. But as before, there are a few scientists who question these events to be directly linked to global warming.

To end this discussion, let’s assume that the recent temperature increases have been caused by human activities, and that there are serious repercussions as a result. This brings up the final question: What can be done? In simplest terms, the goal is to reduce greenhouse gas emissions from fossil fuel burning, along with decreasing deforestation rates. Neither will be easy to accomplish. As our population grows, trees will continually give way to other land uses. And as President Bush stated recently, “America is addicted to oil,” an addiction all too common across much of our planet. While politicians wait as scientists continue to collect data on this issue, individuals can take steps to reduce their greenhouse gas emissions by improving the energy efficiency of their homes, and by making conscientious decisions regarding vehicles and driving habits. In the meantime, one thing we do know for certain regarding global warming is that the debate will continue to heat up.

As with any topic, too much information on global warming can be found on the internet. An excellent site that is both informative and objective is the EPA’s Global Warming page:
A similar one for kids (and even adults) is also available:

Most of the topics discussed above are explained in more detail on these sites. In addition, I used information from to help explain natural variations in the earth’s climate.

Dave Perault is an Environmental Science professor at Lynchburg College in Virginia. When not teaching about the environment, he can usually be found outside enjoying it.


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