To see the usual arguments for global warming, look no further than this list, which gives the most popular “skeptic arguments” with rebuttals. The person who made this list presumably read lots of stuff and tried to select the best rebuttal in every case.
That reading led to this:
Skeptic argument: Models are unreliable.
Rebuttal: Models successfully reproduce temperatures since 1900 globally, by land, in the air and the ocean.
Notice what it doesn’t say. It doesn’t say Models have successfully predicted temperatures . . .Â
These models have many adjustable parameters. With enough adjustable parameters, you can reproduce anything. The only reasonable test of a model with many adjustable parameters is how well it predicts.
Hal Pashler and I wrote a paper pointing out that psychologists had been doing something similar for 50 years — passing off models with many adjustable parameters as reliable when in fact they hadn’t been tested — when their ability to predict hadn’t been measured. One explanation of the current global warming scare is that there is something to be afraid of. A more plausible explanation, I believe, is that — again — one group of scientists is passing off complex models with many adjustable parameters as reliable when in fact they haven’t been tested.
An intelligent and rare insight, coupled with a brave topic.
I salute you, sir.
I believe you that complex models are often unreliable. But suppose mainstream scientists’ complex models were instead predicting a stable climate — would you then be writing skeptical blog posts suggesting we should be afraid of climate change?
M, in the absence of reliable models I fall back on data that bears on the question without needing a model. In the case of climate change, current temperatures are not unprecedented — the Medieval Warm Period, for example. That makes it harder to believe that humans are causing unprecedented warming. So the answer to your question is no, I would not be saying we should be worried about climate change.
Your approach sounds reasonable (ie, “falling back on data that bears on the question without needing a model”). You point to the Medieval Warm Period. The skepticalscience list that you linked to says: “Globally temperatures are warmer than they have been during the last 2000 years.” https://www.skepticalscience.com/medieval-warm-period.htm
The ability of really, really smart economists (with a pair of Nobel Prizes between them) to create highly accurate models based on past economic performance is why Long-Term Capital Management runs such a successful hedge fund today. Oh, wait, maybe not.
M, a few years during the 1930s were also really hot. If you leave aside the models, the rest of the data doesn’t make a good case that it is so much hotter than ever before we should be concerned. If that website had started by realizing the models are worthless, I might trust it. Since that website takes the models seriously, I don’t trust it.
I seem to recall that climate modelers predicted in the ’90s that it would be noticeably warmer today than it was then. Sure enough, it is, and by the amount they predicted (i.e., their worst-case scenario, which is what the data really indicated). Lately, every year is, or matches, the warmest on record. What makes that not a successful prediction?
Nathan, if we’re going to base gazillion-dollar decisions on these models, we might want something a little more extensive and precise than the assessment you’ve just given (“I seem to recall . . . “).