Tuesday, January 20, 2009

4 out of 5 dentists recommend it!

4 out of 5 dentists recommend Trident Image Credit: Brian Dunn / GraphJam

Back when I was a kid, a gum company ran a successful series of ads, claiming that 4 out of 5 dentists recommended their brand of gum. The concept is that dentists are smart, caring people who should know if it is safe for your teeth to chew gum. And I think that most of us would agree that dentists are indeed very intelligent and know a lot about teeth and gums.

Now, suppose you go to your dentist, and she says there is a problem with a spot on your gums, perhaps due to an infection in a tooth, so she's referring you to an oral surgeon. You go to the oral surgeon, who says that the spot looks like cancer. The oral surgeon asks you if you chew tobacco, and you honestly reply that you do. The surgeon says that the cancer was probably caused by chewing tobacco, that he can do surgery that should get rid of the cancer, and that you need to stop chewing tobacco.

On hearing this bad news, you decide that you need a second opinion. After all, your dentist thought it was an infection. And, since you want a representative sample of oral surgeons, you ask another 99 opinions. In total, 97 of the 100 orals surgeons you go to say that you likely have cancer, and that it was likely caused by chewing tobacco.

Not satisfied, you go and get the opinion of 100 dentists. 90 of those 100 say, yes, you likely have cancer, and 82 of them think that chewing tobacco caused it. (That would be 4 out of 5 dentists, and remember how we always joked that there was something wrong with the fifth dentist?)

Next, you ask 100 dental hygienists about your problem. Most of them will claim they don't have the proper training, but if you force them to give an answer, 62 of them say that you could well have cancer, and that the tobacco caused it.

Lastly, you ask 100 Tobacco Institute scientists, and only 47 of them think that you have cancer that was caused by their product. (Still, that's more Tobacco Institute scientists who ever would have claimed that lung cancer was caused by smoking.)

So, now, who would you believe? Frankly, I'd go with the oral surgeons. Yes, everyone you've asked has had extensive training in teeth and gums and related diseases. Some (like the Tobacco Institute scientists) clearly have ulterior motives not to tell you the truth. Others, like the dental hygienists, certainly have lots of training and mean well, but oral cancer and the scientific evidence behind the causes are not the focus of that training. And if 97 of 100 oral surgeons said "You have cancer, and chewing tobacco caused it," would you believe them? I think most people, after some introspection, probably would. The consequences of not believing them are a matter of life and death.

So, that whole story was a hypothetical preparation for the real thing. A news story was released today that have the results of a survey asking several groups of people: Have global temperatures increased over pre-18th century averages? Is human activity a primary factor in that change? Let's look at the results:

  • Among climatologists, scientists who actively study the climate through observations, theory, and computer models, 97% of them agree that temperatures are increasing, and that humans are the primary cause. 97%.

  • Among scientists in general, 90% believe global warming is occurring, and 82% believe that humans are the primary cause ("4 out of 5 scientists agree...")

  • In what surprised me at first, only 64% of meteorologists believe that humans are the primary cause of global warming. However, on further thought (and through prompting in the article), meteorologists are scientists whose job is to produce and convey short-term forecasts. Most meteorologists do not work daily in global climate studies. And the report on the study doesn't make it clear what constitutes a meteorologist; would a television weatherman count? Most TV weathermen are well-trained, but not all of them are, and many do not actively participate in ongoing scientific research (one thing I've learned in astronomy, is that not doing research in a specific area means that one quickly falls behind on the current state of the science).

  • And, not surprisingly, only 47% of petroleum geologists (scientists who look for oil) believe in human-caused global warming. Many of these are paid by petroleum companies, and so have reasons not to believe in man-made global warming. Further, geologists typically get little training in climatology, and petroleum geologists certainly are not active researchers in climatology.

So, who are you going to believe? I defer to the climatologists. They are the most knowledgeable, are on the cutting edge of climate research, and they have no motive to misconstrue the data. And of that group, 97% believe that humans cause global warming. That's 97 out of every 100 climatologists, way beyond 4 out of 5. It's hard to get 97 out of 100 people to agree on what color a wall is painted or even what day of the week it is. But 97% of them are certain that the Earth is warming up and that humans are the primary cause of that warming.

So, the next time someone tells you that we don't even know if the Earth is warming, let alone why, remember that 97 out of every 100 trained climate researchers strongly disagree with both of those points. Ask yourself who is more likely to be right. The answer could have a profound impact on your life and the lives of your descendants. Me, I'm going to side with the climatologists.


  1. Um how many Climatologists were surveyed? The article says 3,146 scientists were surveyed but doesn't say what the breakdown of that number is. What if they only had 5 climatologists, 4 of which were from East Anglia University? Would that make a difference? Do you not think that maybe JUST maybe a climatologist would be just a little more biased towards something that brings them lots of dollars in grant money? You say that petroleum geologists don't want us to believe in global warming because oil is their income, but somehow you don't look just as critically at a climatologist when their income is directly related to global warming. If there wasn't global warming then why would governments need to pump so much money into climate research?

    And what do governments get out of global warming? Hmmm, that's a tough one. Well if us little people are spewing out too much CO2 well then we'll just have to be taxed and taxed until we change our nasty little ways, won't we? Of course none of our "representives" will have to sacrifice like the unwashed masses will. No, no they'll buy carbon offset credits and that'll make everything a-ok!

    That kinda reminds me of some history. I believe it was in the middle ages when the Catholic Church allowed royalty to buy their way out of sins. You know, do a little rape or murder and then just give your local bishop some gold and you're all squarsies with God. Sounds like a good deal...for those who could afford it of course.

  2. Anonymous11:25 PM

    Some global warming may be occuring, but could very well be due to natural causes as well as human ones. It was not extensive use of pollutants and petroleum products that ended the Ice Age, yet that too was global warming.

  3. I agree. Its so easy to look at everything we are doing and to say it is wrong. The planet has gone through many stages of evolution all on its own without human intervention and polutant. I do feel we play a part but its just a part of the bigger picture. We have evolved on this planet with the ability to progress and create and every step we take has a meaning and a direction. We can only do so much to protect our planet but we cannot stop its own natural growth and development.

  4. Anonymous3:49 PM

    Funny how you related your article on global warming with opinion about a dental condition. I'd probably side with the pros on this one too, like I would with a practitioner for dental plans new york about his opinion on tobacco-chewing.