Obama’s green guru calls for white roofs

One of the many things about politics and political reporting that I find annoying is the eagerness with which the reporters will “interpret” what was said, and this story appears to be no exception. It’s hard to say for sure, because precious little of what Chu actually said is quoted, so one doesn’t know how much the reporter is making up. The other point that comes up here is how very different politics and science are.

What he is actually quoted as saying:

“If you look at all the buildings and if you make the roofs white and if you make the pavement more of a concrete type of colour rather than a black type of colour and if you do that uniformally, that would be the equivalent of… reducing the carbon emissions due to all the cars in the world by 11 years – just taking them off the road for 11 years,” he said.

Now, what he didn’t say was that we are actually going to force people to do this — there’s no mention of a policy initiative, or a spending bill to hire TomSawyer Inc to whitewash everything (or, more specifically, to subcontract out the whitewashing to other companies at an enormous profit). It is, at its core, a statement of science that can be buttressed or argued on points of fact. People familiar with scientific analysis might recognize the physicist presenting the idealized case: how would reflection vs absorption change if we went from a black surface to a white surface, and what is the equivalent effect of doing that. The point of such an analysis is a first pass at deciding whether it’s a worthwhile endeavor, an attitude which the president has been trying to re-instill after an eight-year absence. Engaging in this kind of exercise indicates whether or not further action should be taken; if the numbers were different, one could come to a different conclusion about how worthwhile such an effort might be. Here is a distillation of what Secretary Chu said: the albedo of the earth is a large effect in the global warming picture. Here’s how big. There. That’s it. Now, start your engines and decide how one might go about leveraging this idea, or if it should be applied — that’s where politics comes in.

But this is not the direction the article takes, and furthermore, not what many comments attached to the article reflect (at least, as far as I got in reading them). It’s amazing, and not a little bit scary to me, that people feel free to criticize things they obviously don’t understand, the first of which is that science is not a democracy. The reflectivity of concrete as compared to blacktop is not a political question, and the answer does not depend on whether you are conservative or liberal. You are not entitled to have an opinion about factual things. “Blue is a nice color” is an opinion. “The sky scatters blue light” is not. When you exercise the right to make political decisions, you also have the responsibility to make sure that these are informed decisions.

So let’s look at a little physics that’s botched in the comments.

There is only one flaw with this, in the article it states “More pale surfaces could also slow global warming by reflecting heat into space”

Opps, you’ve forgot the critical thinking again professor – All that heat will be reflected into our atmosphere BEFORE it ever reaches OUTER SPACE, so therefore it will warm up the ambient air temperature first, achieving the exact opposite of its desired intent, pretty much what all liberal ideology is guilty of….

So, what else ya got, genius?

and

While the white roof and paving surface will indeed lower energy consumption, and heat island effect, it certainly will not ‘reflect heat back into space’. So called greenhouse gas will trap heat from a white roof, just as a black one. So, the idea of low albeito surfaces in urban areas does have some merrit, for energy reduction.

Reflected light has the same spectrum as the incoming light, while re-radiated light has a blackbody spectrum of a much lower temperature, and is shifted from the visible out to a broad peak at 9 or 10 microns. The problem of CO2 in the atmosphere is that it absorbs at 4 and 14 microns, which are wavelengths present in the reradiated light.

Wrongo! This idiot green energy czar is nuts. Painting roofs white can help save money in the summer by keeping the building cooler and a need for less airconditioning. However, a dark roof is better for absorbing sun in the winter and help keeping some snow and ice off of it. There are trade offs to everything. The next thing you know, the all wise government will be banning air conditioners!

One thing this “analysis” misses is that it’s easier to heat things up than cool them down an equal amount. Thermodynamic processes are not 100% efficient when trying to do work, because there will always be rejected heat. But heating? There is no waste heat, overall. Just an issue of losing energy if you’re trying to transport it (e.g. heating your basement, where the furnace is, but not something you want to warm up). I’m Ignoring the FUD about banning air conditioners. I live in the DC area. There’s no way the US government will ban air conditioning.