I joined the tail end of the discussion. Posted by Scott Sumner In it he discusses global warming, which I posted in my comment, but which may have been noticed too late by most people.
I think the issue is more complicated than Scott suggests.
Scott writes:
According to theory, rising carbon dioxide concentrations should cause the Earth’s temperature to rise due to the “greenhouse effect.”
truth.
But that doesn’t tell us how strong the effect is. I’m not disagreeing with Scott, I’m just saying that the effect can be strong or weak. If a large increase in CO2 leads to a 0.1 degree increase in temperature, there’s little to worry about. You can’t just look at the fact that CO2 increased and temperatures increased and attribute all of the temperature increase to increased CO2.
Let’s take an example from the world of economics, which, of course, Scott and I are very familiar with. We assume that a large increase in the minimum wage will significantly reduce the number of low-skilled jobs. This is good economic theory. If we look at the data, we see that, indeed, when the minimum wage increases by a few dollars an hour, it significantly reduces the number of low-skilled jobs.
But that alone doesn’t tell us how much of the employment decline is due to the minimum wage increase.
Similarly, focusing on one variable, CO2 concentration, without considering other factors that may cause global warming is a flawed methodology.
