Is a Little Ice Age Upon Us?

Some scientists seem to think so.


1) The headline to the article linked above is sensationalist. The truth (as I gather from the body of the article) is that some scientists at or associated with NASA think we may be entering a little ice age. That is interesting, but not what the headline says.

2) If it is true, it does not mean that global warming theories have been wrong, or a "hoax," as some people absurdly have contended. What it means is, that like all scientific theories, these theories can only account for a certain range of phenomena, and when something outside the scope of the theory enters the picture... well, the theory doesn't account for that.

An example:

The government of Ruritania gives each citizen in its capital of Ruropolis the equivalent of a million dollars of the local currency, which it has just printed. An economist predicts, "Ruritania is about to see some wicked inflation."

The very next day, Ruritania's enemy, Freedonia, drops a nuclear bomb on Ruropolis, wiping out all of its citizens, along with their newly issued fiat money. No inflation ensues in Ruritania.

That does not mean the economist was wrong! We teach our students that our economic models apply ceteris paribus, but in this case, the ceteris were extremely not paribus. Economists do not include the possibility of nuclear attacks in their models, and rightly so: the usefulness of models derives from the fact that they simplify the world for us, and allow us to understand a very complex world through the lens of a much simpler model. But we must never forget the simplification involved: any model will only be applicable when the factors it ignores in its simplification have a negligible effect on some real situation. When one of those ignored factors becomes important, the model may be completely useless.

And it is not only economic theories that are only true ceteris paribus: all scientific theories are like this. E.g.: I drop a rock off of a cliff. A physicist says, "The rock will fall to the ground below with an impact derived from its mass and the equation for falling bodies, modified by the factor of air resistance."

But just after I let the rock go, someone hang-gliding snatches it from the air and carries it off with them. That does not prove the physicist wrong! His theory only holds ceteris paribus, and it did not include hang-gliding rock collectors in its equations.

The application to global warming theories should be obvious: these theories have attempted to model the effects of human activities on the global climate. The models involved may have been very accurate (I don't know: I am no climate scientist!), but they did not include a sudden decrease in the energy the sun is sending earthward in the model. And that is no black mark on the models!

3) If it turns out to be true that we are entering a new little ice age, the irony level will be remarkable: the global warming models may turn out to have been extremely accurate, but the worries unfounded, since the warming we have been creating actually may wind up acting to ameliorate the (apparently) devastating effects of the cooling that some scientists are now predicting.

4) My comments here are from the perspective of the philosophy and history of science, two subjects which I have studied a fair bit. I have absolutely nothing to say about global warming models or these predictions of a new little ice age, since I have studied climatology and solar astronomy not at all!


  1. Gene, it would have been better if this issue came up at a time other than right after we argued over behavioral economics, but sunk costs are sunk so let's put that fight behind us (ha ha)...

    I agree with you that the "skeptics" will make more of such quotations than is perhaps warranted, and it's why I personally don't get excited anytime I see some new paper challenging the orthodox climate science position.

    However, the impact of the sun on the Earth's climate system is not some new proposal, which the existing computer models haven't considered. This chapter from the IPCC lists the various contributing "forcing" factors to the temperature.

    Look in particular at the table on page 696. It shows that the estimated contribution of solar irradiance to changes in the Earth's temperature since 1750 were thought to be less than 2% of the contribution of greenhouse gases as of the last time the official estimates were quantified, and then in the next edition of the IPCC report it says only that they now think solar irradiance is even less of a factor (without putting a number on it).

    Like you, I am not saying this article you've linked to is right or wrong. Also, I agree that regardless of what happened, it would be wrong to dismiss all of this stuff as a "hoax" because I know there are many rank-and-file scientists who think they're doing good work.

    But the people warning of the disasters of runaway global warming can't really say, "How could we have known the sun was such a big factor? We were right." One of the leading "skeptic" arguments for decades has been to say the sun plays a much larger role than greenhouse gases, and that humans don't have as much influence on observed temperature trends as the alarmists think. So yes, this would indeed be a huge blow to the "consensus" and "the science is settled" crowd if it turns out to be true.

  2. I agree models can be useful or not, but how is this attribute applicable to theories? Is there not a difference between models and theories?

    1. A model is simply a mini-theory expressed by the building of a construct that represents some aspect of a larger theory, which may contain a number of models.

  3. The guys quoted in this article are cranks. Casey isn't a climate scientist. He's a retired engineer who self-publishes most of his stuff on the internet (he did used to work for NASA, but it was on the shuttle).

    Leaving that aside, I have to side with Bob here. The IPCC gives temperature forecasts that are supposed to be 95% likely. So I suppose if we have just entered a new ice age they could say it was part of the other 5%. But practically speaking it would be a pretty amazing thing for them to miss.

  4. To put it another way, it's not as if Casey et al accept what's in the IPCC reports but thing they've found evidence of something else the IPCC didn't account for. No, they think mainstream climate science is bogus.

  5. Josiah and Bob, please see my new post on this topic.