Four out of five dentists prefer sugarless gum!
If four out of five dentists prefer sugarless gum, then it makes you wonder if you should really trust that 5th sugar-loving dentist with a large metal spike in your mouth. But maybe, just maybe that 5th scientist knows something the others don’t. Then again, maybe he’s simply a total nut case. The point is, questions within the scientific community spark debates and these debates often serve as the checks and balances of the topic in question. A recent debate, which is sparking heated arguments from all sides, is global warming. This topic has been addressed ad nauseam in the recent months, which has caused many people to come up with their own ideas on the issue, ideas that may or may not be valid. For that reason, I feel it’s time to address the issue based on what is fact and what is not. I’ll simply talk about the specific issues I’m asked most frequently and the talking points on each side:
1) Q: Is global warming real?
A: This question is specifically asking whether the overall surface temperature of the earth is warming. The answer is “yes,” with both sides of the debate agreeing that the surface temperature of the earth has steadily warmed over the past century with the top 10 warmest years occurring since 1990. On a side note: The increase over the last century has been about 1 degree, so when we have a heat wave this summer and everyone starts shouting about global warming you will know the hot temperatures are occurring because it’s, well, summer. Global warming is real, but blaming a hot summer day on global warming is a bit of a stretch.
On another side note: I have heard some people refer to Michael Crichton’s book State of Fear, in which he makes the point that some of the thermometers making these measurements are located within growing cities. Growing cities mean that over time, more heat absorbing materials such as concrete are added to the area around the thermometer. This, of course, would lead to warmer temperatures. While this phenomenon is true (it’s called the urban heat island effect), it still means the temperature is increasing. There are also several temperature readings outside of urban areas that show warming as well. If that isn’t enough there are data called “proxy” data, which serve as indicators to variations in temperatures (such as retreating glaciers).
2) Q: Some glaciers are actually growing…what’s up with that?!
A: This is true, some glaciers are growing. However, the majority of glaciers and the major ice sheets (including the polar ice cap) are retreating significantly (20% of the polar ice cap has melted away since 1979…by the way, that’s a lot of ice!). The ice sheet covering Greenland is also melting quickly and this is what has caused a good deal of concern. If these do melt, sea levels will go up. The flip side to this is: if these glaciers continue to melt, they will dump cold, fresh water into the ocean, which could lead to alterations in ocean current circulations. Could these alterations shut down the Gulf Stream and other major ocean currents? If so, would this lead to continued warming, or send us into the next ice age? These are where the debates exist and I recommend you look at the 2007 International Panel on Climate Change (IPCC) report as well as a host of other documents on this particular issue.
3) Are humans the cause of the recent global warming?
According to the 2007 IPCC report, it is highly likely that human influence is at least partially to blame for the recent warming. Other scientists, including some well known scientists actively arguing against the global warming hype, such as Dr. Gray of Colorado State, generally agree to this, but they say the impacts are extremely minimal. Many other factors contribute to climate variations including solar activity (google “Maunder cycles” for more info), the way in which the earth is oriented toward the sun (see precession, tilt, and obliquity for more info), and natural variations in the earth/atmosphere chemistry. Therefore, there are other causes for climate change, but the evidence strongly supports the idea that humans are at least partially responsible for the warming.
4) Will the climate continue to warm / how bad will it get?
This is the main meat of the debate, plain and simple. While, the data provided by most climatologists suggest that the planet will continue to warm (anywhere from 1-10 degrees over the next 100 years), there are others who claim it is impossible know what will happen due to complexities in the climate system that we don’t understand. I, for one, can certainly see both sides to the argument: On the one hand, we are pumping copious amounts of green house gasses into the atmosphere, which certainly would increase the surface temperature if everything else is held constant. On the other hand, nothing is constant and this is where things get extremely complicated.
For example, if we warm the earth then more evaporation can occur, which will lead to more heat trapping water vapor in the air, which will lead to even warmer temperatures, which will then lead to more water vapor in the air, yada, yada, yada, the earth boils and it’s now end of the world, right? Well, not so fast. If there’s more water vapor in the air, then there should be more clouds, which reflect sunlight, which would lead to cooler temperatures. BUT, if these clouds are low clouds and not high clouds then this will trap in heat at the surface leading to warmer temperatures…ARGGG! This is just a VERY small sample of the complications in forecasting the climate. In the defense of the climate models making these forecasts, they are extremely complex and they do an incredible job accounting for these complexities. Each climate model has its own set of parameters that can be tweaked within reasonable limits to test the effects certain parameters (like carbon dioxide levels) have on the climate system. This is partially the reason why the range for warming in the next 100 years is so large (1-10 degrees).
Whether the earth continues to warm or not, my greatest fear within this topic is that it becomes so overly hyped that no one cares to listen to those that have credible evidence now, or in the future. The questions addressed above are simply abbreviated answers to the most common questions we receive. If you have additional questions, comments, or packs of sugarless gum, please feel free to send them our way…4 out of 4 KBTX meteorologists will appreciate it!
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