There’s been a lot of hot weather east of the Rockies lately. I really feel for the folks in the mid-Atlantic states who have no power for refrigeration, let alone air conditioning. I’m sure somebody will bring up the idea that this is all due to global warming — excuse me, climate change. I’m also sure that somebody will point out that we’ve always had hot weather.
What a lot of people on both sides of this issue don’t seem to understand is that climate and weather are not the same. A spate of hot weather and vicious storms, as the mid-Atlantic states are suffering through, is a spate of hot weather and vicious storms. It isn’t evidence, one way or another, for climate change.
Climate change is a matter of long-term trends. Fundamentally what happens is that the average amount of energy trapped in the earth’s atmosphere, seas, and land changes. That’s the whole earth, not just Cleveland.
If the atmosphere, seas, and land just sat there like a pot of still water, adding heat would cause the temperature to rise somewhat. After all, adding heat to a pot of still water would cause the temperature to increase until the water was about to boil. The temperature of the water would gradually increase to 100°. Cooling the pot by removing heat (energy) would cause the temperature of the water to decrease gradually to 0°. [This is very simplified. To give myself a little credibility I’ll follow up with comments down at the bottom of this post.]
In reality, though, the atmosphere, seas, and land do not just sit there like a pot of still water. The winds blow, the currents flow, and the land changes as vegetation and precipitation come and go. The whole kit and caboodle is constantly moving in big and small ways. Energy is constantly being shuffled around. If you live on the east coast, you know that hurricanes gain strength over warm water and lose strength over colder water. Thunderstorms, under the right conditions, can form tornadoes. The jet stream wanders around, and the ocean currents change.
That’s why global warming will not have a uniform effect, just making the weather get a little warmer all over the world. When you have that many moving and interacting parts, adding energy to the system makes everything move and interact with more vigor. The jet stream wanders farther and faster; hurricanes find more warm water to feed on; high pressure areas get higher and low pressure areas get lower; and in general the extremes get more extreme. It’s like giving espresso to a room full of kindergarteners.
If the earth trapped more energy from the sun, the yearly average temperature in Kansas City might go up by only a degree or two; but there’d be more hard freezes and heat waves.
If it were just temperature we had to worry about, we could deal with that the way our ancestors did: sweaters in the winter, sweat in the summer. The really big problems would be a lot worse than personal discomfort. You’ve probably heard about some of them:
- Because of the higher average temperature, the glaciers would melt away (robbing many places of their source of water).
- Likewise the polar ice caps would melt, raising the sea level. Think about what Katrina did to New Orleans, and extrapolate that to every seacoast city in the world. Not even the Dutch with all of their dikes could deal with that.
- Polar bears would die out; or perhaps they would adapt and migrate down to your neighborhood.
- Because there would be more energy in the system, the atmosphere’s behavior would become more chaotic. All of the things that come from pressure gradients, temperature gradients, and so forth would be accentuated: windstorms, heat waves, tornadoes, hurricanes, and the like.
- Rainfall patterns would shift in ways we can’t predict: the Sahara might bloom, and the US corn belt might turn to dust; or the Sahara might get bigger and the US corn belt might become a giant rice paddy.
- Food availability in general would change. We might wind up eating anchovy-flavored Pop Tarts.
- In the very worst case, the whole mess would become a vicious cycle and the warming would accelerate until the earth became uninhabitable.
Some sceptics maintain that climatic cycles have always been with us, and they point to the ice ages as proof. Well, suppose they are right and that this is all a natural phenomenon. That doesn’t change a thing, in terms of what we should be doing.
Right now the climate is pretty comfortable for us, and we need to preserve the status quo. We don’t want to make the climate any warmer than it would naturally be; in fact, we want to put the brakes on any natural warming might be in our future. Likewise we’d want to stop the climate from getting colder, but since objective measurements show that it is getting warmer we don’t need to deal with that right now. It’s the warming that has to be stopped, if we can.
- Even a pot of “still water” doesn’t remain still as you add heat. It’s pretty much impossible to heat all of the water uniformly, so you’ll get convection currents. If water in a pot heated uniformly, you wouldn’t get that bubbly boiling effect: it would all suddenly become a puff of steam.
- I left out any mention of state changes. I was just drawing an analogy, after all.
- When it comes to adding energy to a system, no matter how simple, you can get a lot of counter-intuitive behavior. For example, consider a piece of copper. You can’t get much simpler than that. You’d think that if you applied heat to one end, the heat would propagate smoothly down to the other end until the whole piece of copper were the same temperature. It doesn’t. You actually get oscillation-like behavior. (Please don’t ask me to prove this. I had enough trouble with the math 45 years ago, and it hasn’t gotten easier.)