Astromike23

Wow, getting closure on this after ten years is surprisingly cathartic. Thanks for replying!

Hi Alex! When I was applying to astronomy grad programs almost a decade ago, I spoke to you on the phone about applying to Berkeley. In spite of having a very high physics GRE score, you told me that I would be wasting my time because your program is "academically rigorous, so we doesn't accept people with B.A.s in physics." I was so taken aback by your answer, I never got to ask: Why? I understand the importance of screening out folks who don't have the required physics background, but the criterion for applicants who earned a B.A. in undergrad seemed weirdly arbitrary.

(Side note: I ended up attending a different top-tier astronomy program, and now have a prestigious postdoc.)

Hey, so I got my PhD researching planetary atmospheres. You raise a few points...

This climate model.

https://static.skepticalscience.com/pics/layer.jpg

So that's actually a 1-D radiative transfer toy model. You're definitely right, it should not be used to predict climate - in fact, I wouldn't even call it a climate model.

We use it to teach undergrads how the greenhouse effect works because it's literally the simplest model you can build that produces close matches to the actual temperatures observed on some of the planets. But again...it's way, way too simple to model climate. No one should use it to do real science, and none of the climate models I've used or have seen use any kind of radiative transfer this simple.

They have taken the suns energy and divided it by 4 and spread it over the entire surface area of the earth at once.

Making it a useless model with no basis in reality whatsoever.

So this actually depends on two things: how fast the planet rotates vs. how quickly it cools off to space. The 1/4 approximation works really well at predicting the average temperature of a body, so long as a point on the surface of the nightside of the planet can get back into the sunlight before it loses most of its heat to space. If it loses too much heat, the rate at which it cools to space also slows down, and the approximation no longer holds.

The approximation works well for predicting average temperatures on Mars, Earth, and most of the asteroids. On the other hand, it's terrible for predicting the average temperature of places like the Moon and Mercury.

If you want to understand more watch this. It's Canadian astrophysicists Joseph Postma explaining that there is no such thing as a radiative greenhouse effect.

So his mistake is actually pretty close to the beginning, around 6:00 in. He's forgetting about thermal inertia.

Your turkey example is a good one. Imagine you put a thermometer on each side of it, put it on a spit, and rotated it over a fire. Now if you rotate it really slowly, then yeah, you're probably going to see a temperature difference between the side facing the fire and the side facing away. As you turn the spit faster and faster, though, the two thermometers will start getting closer and closer in temperature, converging on the average temperature of the turkey.

If you work the math, it turns out that having one hot fire will produce the exact same average temperature as surrounding the turkey with fire that's 1/4 as hot...so long as it's rotating faster than the dark side can cool. Again, that's why this fails miserably if you want to estimate the temperatures of Mercury or the Moon.

Just FYI, even Roy Spencer (who makes a lot of mistakes like this) debunks this argument correctly.

They stole the name green house because what happens in a green house has nothing to do with their made up greenhouse effect.

You're definitely correct that actual greenhouses are not primarily heated by the greenhouse effect. You can build a greenhouse out of panes of salt (which is transparent to infrared light) and it will climb to almost the same temperature as a glass greenhouse; ultimately it's suppressed convection that causes the vast majority of heating, the same reason that blankets keep you warm.

I'm not sure it's quite right to say the name was "stolen", though. The name actually comes from back in the 1820's when Fourier correctly realized that Earth was a fair bit warmer than it should be if warmed only by the Sun, and wondered if the atmosphere might be responsible. He became aware of de Saussure's experiments on the heating of air between glass, thought they were similar to his own theory, and mistakenly named his theory the "greenhouse effect" (though he did also recognize that suppressed convection was an important difference between the two).

It's definitely a misnomer, and it kinda sucks we're stuck with the name...but I guess we still call them koala "bears", too.

It's a shame, since Lindzen actually did some pretty ground-breaking work back in the late 70's/early 80's on the nature of the seasonal Hadley Cell.

Even then he was known for being argumentative, but after he started taking money from Western Fuels, everyone in the field has sort of dismissed him as just being intentionally obstinate in spite of the mountain of evidence.

maybe 200,000 years inferred data

You seem to be thinking of only certain Greenland ice cores. The Antarctic Law Dome ice core goes back 800,000 years.

Meanwhile, Delta-O-18 measurements from benthic sediments can be used to reconstruct temperatures for the past 500 million years (Royer, et al, 2004, PDF here).