It’s currently the “in” thing to talk about anthropogenic global warming (AGW), which is the notion of global warming being caused by human activity. Whether AGW is real or not is not the point of this post, however. Neither is debate over whether “climate change” (a term usually conflated with AGW in popular culture) is a bad thing or not. Rather, I’m going to consider a couple of mechanisms that might lead to the AGW effect.
First, the current focus is on emission of greenhouse gases (GHG). The theory is that as the concentration of GHGs in the atmosphere increases, the proportion of energy radiated by the Earth that gets reflected back to the Earth increases. This effect is real and has been adequately demonstrated many times in laboratory conditions. GHGs includes such things as carbon dioxide but it also includes water. Yes, good old garden variety water is a GHG.
There are two good reasons for the fixation on GHGs. The first is that it is easy to get people on board for measures to “reduce emissions”. After all, many GHGs are also toxic for other reasons and who wouldn’t want to reduce pollution? The second reason is that the average person can see how we can do something about GHGs in the short term.
Fixating on GHGs, however, is focusing on exactly half of the equation. Consider that at its simplest, a change in temperature is simply a change in thermal energy. Thus, if thermal energy input is greater than thermal energy output, you have an increase in temperature and if it is less, you have a decrease. The actual details are quite a lot more complicated. In this discussion, we will consider the energy contained in the atmosphere since that is the quantity that affects climate.
Now let us define a couple of terms. There are sources of thermal energy which simply add thermal energy to the system. There are also thermal energy sinks which remove energy from the system. I will refer to these simply as sources and sinks.
There are several sinks at work. One is heating up objects such as the ground or melting ice. The ability for objects or ice to serve as sinks diminishes as their overall temperature approaches the temperature of the atmosphere and, thus, are not a viable long term energy sink. Another sink is simply radiating energy into space. This process is constantly occurring. It is this process that GHGs impact. Higher concentrations of GHGs reduce the radiation ability.
The idea behind controlling GHGs is that by reducing GHGs, the sink rate of radiation into space increases, and thus the rate of warming is reduced. It is interesting to note that this is something of a balancing act since if GHG concentration is too low, radiation to space would actually be sufficient to cause global cooling which, if unchecked, would also be disastrous. Global cooling, however, would be easier to combat.
As mentioned previously, however, there is another side to the equation. We must also consider the sources. After all, if you reduce the energy input, you also reduce the rate of increase. So let us consider some sources.
One obvious source is the sun. Its output varies over time which does have some impact on the atmosphere. Additionally, the amount of solar energy that gets collected depends somewhat on cloud cover, too. Another source is objects radiating heat into the atmosphere, water freezing, and so on. Often these objects get heated up above atmospheric temperature by absorbing solar energy. Thus, the composition of the Earth’s surface impacts solar absorption by the atmosphere too. Energy from molten rock from inside the Earth also ends up in the atmosphere.
There is, however, another source of heat that goes into the atmosphere. This is the result of energy use in one form or another. This might be in the form of biological processes (metabolism), for instance. Or it might be in the form of burning wood or coal for heat. But it also comes from electricity generation, electricity use, internal combustion engines, external combustion engines, windmills, waterwheels, and so on. In other words, much of the activity of a high technology civilization is a heat source.
You might argue that using energy sources already on the Earth cannot release more heat than is already here, but remember that all energy sources are converting a stored potential energy into usable energy and waste heat. The net total energy of the entire Earth and atmosphere does not change, but the net energy in the atmosphere goes up by the same amount the stored energy in the Earth goes down. Because the atmosphere has a great deal less mass compared to the Earth, the overall impact on it is much more dramatic. And remember, we’re considering the atmosphere on its own here, not the whole system including the Earth itself.
Now here is the interesting part. Assuming a constant population with a constant life style (which is absurd, by the way), most methods of reducing GHGs will also have some impact on the total heat emission from technology. For instance, walking instead of driving both reduces waste heat emission and GHG emission, thus improving both sides of the temperature increase equation. (It has other benefits as well making it a net win where practicable.)
So, let us now assume that AGW is a problem (it probably is but if you disagree, just pretend it is). We want to reduce the rate of temperature increase to as close to equilibrium as we can. We can try to do this by reducing GHGs alone, but this is difficult and has a fair lag time before impacts can be noticeable. (The atmosphere is big.) What we can also do is reduce energy usage altogether. This would have the beneficial effect of reducing waste heat. But it would also, in many cases, directly reduce GHG emissions, too, because demand on “dirty” energy sources would be reduced. And it would also buy us more time to find alternative energy sources.
The only problem with this proposition is that everyone wants a high standard of living and the term “standard of living” has become conflated with “consuming lots and lots and lots of stuff at an alarming rate”. Furthermore, the vast majority of the world population is well below this standard of living and wants to get there. To further complicate it, the total population is increasing. All of these factors tend to increase total energy consumption and thus increase both energy consumption (heat output) and GHG output.
Thus we have a problem. Even if, by some magic, we were to eliminate totally our GHG emissions (which is impossible – our own metabolism contributes some at the very least), our energy consumption is going to continue to increase as population increases and standards of living increase. This means the total heat output into the atmosphere from human sources is going to continue to increase. Assuming no change in radiation to space, and even if AGW is not a problem now (which it probably is), if we continue on our current trajectory, AGW will necessarily occur in the future.
So what do I suggest? We of the so called first world drastically reduce our reliance on energy. In particular, places like North America which have been designed around the idea of wasting energy on transportation (sprawl) need to smarten up and stop designing for automobiles. But we also need to reduce our dependence on energy hunger stuff like those eleventy badillion watt entertainment systems, computers, and so on. Go back to washing dishes by hand. Don’t turn on four dozen lights when one will do. All sorts of things like that. And buy less stuff. Buying less stuff will reduce industrial consumption since that stuff that is not bought will not need to be made. Folks in the developing world should upward to the same goal the first world aims downward for. And finally, we need to stop population growth, which is a hard problem.
The astute among you will have realized that the solution above is also a recipe for economic collapse under our current system which requires perpetually increasing growth. Obviously our economic system must be replaced with one that does not require perpetual growth to attain some level of stability. That, however, is a topic for another rant.