Wednesday, March 18, 2009

You're Getting Warmer (?)

This quote from Michael Steele came to my attention by way of Andrew Sullivan:

"We are cooling. We are not warming. The warming you see out there, the supposed warming, and I am using my finger quotation marks here, is part of the cooling process. Greenland, which is now covered in ice, it was once called Greenland for a reason, right?"

OK ... Steele would do well to stay away from microphones for a while, but he's got a tiny, minuscule point buried in there. But it's probably not the one he thinks it is. There's come chicanery going on in the climate change debate, but that doesn't really change the fundamental conclusions.

Here's the graph that started it all:

This graph, based on data analyzed by Mann, Bradley, and Hughes, appeared in the 2001 IPCC report. What this data set appears to indicate is a dramatic increase in temperatures during the 20th Century, a change that was entirely imputed to human causes.

I have had a problem taking this interpretation of the data seriously. The reason for that is that, for a long time, Mann refused to divulge the analytical techniques he used to derive the graph in the first place. As this Wikipedia page shows, he eventually came clean on how he got the data, but still ... in science, repeatability is key. As I said earlier, if you can't describe your procedure well enough for another researcher to duplicate it, you probably don't understand what's going on as well as you think you do, and if you won't, you've probably got something to hide. Now, it's possible (even likely) that Mann had nothing to hide. I tend to assume that most professional scientists have a sufficiency of professional integrity. But for a while there, he acted like someone who was hiding something. And you can't really trust diddled data.

But even discounting that graph, this one was the clincher for me:

This isn't junk processed through some super-secret filter. This is pure hard-core, read-it-and-weep data. The one incontrovertible, undeniable fact revealed by the ice core data is that current CO2 concentrations are at simply absurd levels.

Now, knowing that, what can we reasonably expect? What kind of warming will this result in?

The thing you must realize straight away is that the climate is a Sun-powered machine. Virtually all of the energy within the world's weather systems comes from the Sun. Further, daytime high temperatures are governed by solar heating of the surface, while night-time low temperatures are governed by how much heat can escape into space overnight. Atmospheric composition, then, will have its major effect not on daytime highs, but on overnight lows.

Now, let's look at the heat retention capacity of various gases within the atmosphere. From the Wikipedia article on the greenhouse effect, we see:

* water vapor, which contributes 36–70%
* carbon dioxide, which contributes 9–26%
* methane, which contributes 4–9%
* ozone, which contributes 3–7%

In a damp climate, water vapor dominates. In such climates, water vapor contributes 70% of the greenhouse effect, with CO2 only contributing about 9%. In dry climates, it's a more even split, 36% versus 26%. So, the most prominent effect is going to be in cold, dry climates, such as we see around the North Pole, and in Antarctica. The least prominent effects are going to be in warm, humid climates. I wouldn't expect a huge swing in temperature there due to atmospheric composition.

Now, how does this square with what we see happening? The reduction in Arctic sea ice seems to be bearing this out. There has also been a reduction in Antarctic sea ice. Both cases point to an elevation of low temperatures to the point that the sea ice has begun to melt.

Melting sea ice won't change the overall ocean levels. You can try this for yourself with a plastic cup, some water, an ice cube, and a Sharpie. Put some water in the cup, drop in an ice cube, and mark the water level. When you come back after the ice cube has melted, the level will not have changed. This is because ice contracts as it melts. Glacial ice is another matter entirely, as is Antarctic pack ice, since that melt-off adds new water into the system.

In any case, we're currently running an open-ended experiment on elevated CO2 levels, which is probably unwise. We don't really know with iron-clad certainty what the effects are going to be, but the effects probably aren't going to be especially pleasant. Sooner or later, we're going to have to get a grip on this problem. Besides reducing emissions now, we probably ought to be looking at ways we can reduce the amount of CO2 that's already in the atmosphere. One idea I've heard about is promotion of algae growth in the oceans ... which may be a good idea, up to a point. Done excessively, it can deplete the ocean of oxygen, which isn't very helpful, either.

To make a long story short, I haven't always trusted global warming proponents, but I haven't complained much because we already have a sufficiency of good reasons to get off of fossil fuels posthaste. They fill our air with crud, they enrich people who hate us, and aren't those two reasons good enough by themselves?

1 comment:

Burr Deming said...

Excellent analysis. Thank you.