Anyone who’s been to Maine knows that fog is not unusual, especially near the coast. It can roll in in the morning, burn away quickly as the sun heats the atmosphere, or it can hang on for hours. Sometimes it only remains right along the water; as you drive inland, it rapidly dissipates. We had such a day last week.
On this particular day, the fog would seem to be lifting, only to thicken again before the sun could fully burn it off. This went on well into the afternoon. It never really cleared until about 5:00 PM. Amazingly, people came to the beach in large numbers (early in the day) and never left until late afternoon. For most of the day, the beach looked much like it does in the image above. If you look closely, you can see ghost-like images moving around in the background. The edge of the water is out there as well, although you can’t really see it. Essentially, all of these people ignored the fog. This was a beach day, damn it, and a little fog wasn’t going to spoil things. I talked to one of the lifeguards and he said it was actually a little dangerous because anyone who wandered more than 50 feet into the water couldn’t see the shore anymore. Just my opinion, but I don’t see the point of laying or sitting on the beach in a heavy fog. I suppose the good news is that you’re less likely to get sunburned.
Two things in the news earlier this week (one national and one local) reminded me of this image. The first was on MSNBC Monday night and had to do with a “town hall” meeting given by a Republican congressman in Delaware. The poor guy was just getting started when a woman stood up and, while waving her own birth certificate and a flag, demanded to know why congress had “allowed” Barack Obama to become president when he couldn’t prove that he was a U. S. citizen. He couldn’t produce, she said, his own birth certificate. When she’d finished, she was given a loud and long round of applause. I honestly couldn’t believe it. I know wingnuts like this are out there, but come on. Virtually anyone can see a copy of Obama’s birth certificate online. Yeah, I know. The conspiracy theorists will just say that it’s a fake. Just like the moon landing 40 years ago.
Now maybe this woman only has an 8th grade eductation or maybe she’s been to one too many Sarah Palin rallies. Perhaps she has an excuse for spewing this nonsense. This next guy, however, doesn’t.
In yesterday morning’s local fishwrapper (the Rochester Democrat and Chronicle), a very highly respected local TV meteorologist (Kevin Williams) decided to respond to a previous editorial comment about climate change. The person writing the earlier comment had simply said that “it was logical to conclude that we are responsible for the present rapid rate of disappearance of arctic ice”. Mr. Williams, whose anti – global warming views are fairly well known, was compelled to respond.
“Arctic ice coverage”, he said, “is increasing and is now near the 30 year average and more important climatically, global sea ice is above average”. While he said a number of other things, that was the crux of his argument.
As a statistician, I’ve run into this kind of misrepresentation of the data for over 30 years. It sounds good, and he doesn’t actually lie, but it is wrong nontheless. He’s twisted the facts to mirror his own point of view.
First, you have to understand something about the idea of “average”. That’s pretty simple, right? If I want to know the average high temperature for the last 5 days, all I need to do is add up those 5 values and then divide by 5. The resulting value is the “average”. So far, so good. Statistically, however, there’s a catch. Some averages are meaningful and some aren’t. I could, for example, ask you to take a single page out of the phone book and then ask you to calculate the “average” phone number for that page (using the last 4 digits). Arithmetically, that’s not a problem. It might take a few minutes, but you could do it. But what would it mean? The answer, of course, is absolutely nothing.
Sometimes “real data” falls into the same category. The “average” that Mr. Williams is talking about is one such case. Consider the following graphic:
This chart, provided by the National Snow and Ice Data Center (at the University of Colorado), simply shows the extent of sea ice in the Arctic during the month of June for the last 30 years. They use the June data because it’s an indication of the amount of melting that’s occurring during the summer months. Note the heavy blue line. This line represents the statistically significant downward trend in this data over the 30 year period. It indicates an average decline of 3.3% per decade, or roughly 15,500 square miles of ice per year.
Taking the “average” of this data is one of those times when it makes no sense. It makes no sense because the data is “trending” in a single direction. If you were overweight and went on a diet for 6 months and lost 50 pounds in the process, would you give friends your “average” weight for that period? I don’t think so. You might calculate an average loss per month, but that’s a different number. It has some meaning. Would you calculate an overall average for any reason? No. Intuitively, it is a number that has no meaning.
The more reasonable interpretation of this data is that the extent of Arctic sea ice is declining and has been declining for at least 30 years. I don’t know how anyone – especially a meteorologist – can argue with that. The only possible argument might involve the integrity of the data itself or whether or not the trend is “man-made”. But if you accept the data, there is only one possible conclusion. The amount of Arctic sea ice is in decline.
With respect to “global sea ice”, Mr. Williams is throwing out a bit of a red herring. Scientists have known for years that Antarctic sea ice does not behave the same way that Arctic sea ice does. The same variables that are causing some areas of the globe to warm are actually causing other areas to cool. No one has ever said that the earth is “warming” uniformly. The model used by most scientists indicates that sea ice in the Antarctic is not declining, or at least not at the rate seen in the northern hemisphere.