If you haven’t got enough Superfreakonomics blogging Brian D has collected links to, well, everything.
The response from the authors to the criticism has been underwhelming. Dubner ignores most of the criticism and blames Caldeira for the fact that they misrepresented him. Your must read story on this comes from Eric Pooley, who says that Dubner is an old friend, but none the less reports:
One of the injured parties is Ken Caldeira, a climate scientist at Stanford University who is quoted (accurately) as saying that “we are being incredibly foolish emitting carbon dioxide.” Then Dubner and Levitt add this astonishing claim: “His research tells him that carbon dioxide is not the right villain in this fight.”
That’s provocative, but alas, it isn’t true. Caldeira, like the vast majority of climate scientists, believes cutting carbon dioxide and other greenhouse-gas emissions is our only real chance to avoid runaway climate change.
“Carbon dioxide is the right villain,” Caldeira wrote on his Web site in reply. He told Joe Romm, the respected climate blogger who broke the story, that he had objected to the “wrong villain” line but Dubner and Levitt didn’t correct it; instead, they added the “incredibly foolish” quote, a half step in the right direction. Caldeira gave the same account to me.
That’s pretty damning.
And then we have this post from Nathan Myhrvold attempting to defend this statement he made:
“The problem with solar cells is that they’re black, because they are designed to absorb light from the sun. But only about 12 percent gets turned into electricity, and the rest is reradiated as heat — which contributes to global warming.”
Myhrvold starts by abusing his critics, calling them “shrill”, “bitterly partisan true believers”, “angry bloggers”, etc. He eventually gets around to:
He quotes somebody’s calculation arguing that over very long periods of time, solar cells save emissions. Well, of course they do. It’s so much easier to attack if you take things out of context. …
Over time, the CO2 savings from operating the solar plant (versus coal) would accumulate and be much larger that the warming caused by the “blackness.”
Myhrvold does not tell you how long this takes. Let’s do the calculation:
The atmosphere contains 775 Gt of carbon. Radiative forcing for doubling CO2 is 3.7 W/m^2. Area of the earth is 5.1×10^14 m^2. There are 3.2×10^7 seconds in a year. Coal is 80% carbon. So 1 tonne of coal heats the Earth by 0.803.75.1e14*3.2e7/775e9=6.2×10^10 J per year.
Now, 1 tonne of coal directly produces 2.4×10^10 J of heat, so it takes just 12/(6.2/2.4)=4.6 months before the greenhouse heating exceeds that from waste heat.
So if you are prepared to wait as long as 4.6 months, then your solar cells start reducing global warming.
Myhrvold also wants to include the cost of building solar plants.
Pacca and Horvath, in a 2002 study, found that the greenhouse gas emissions necessary to build a solar plant are about 2.75 times larger than the emissions from a coal plant of the same net power output (1.1 * 1010 kg of CO2 to build the solar plant versus 4 * 109 kg of CO2 per year for coal).
OK, so it takes three years before you are ahead. Still sounds good. So Myhrvold comes up with:
The next part of the point is that we need to build out lots of renewable energy if it is going to make a difference. If we finish one plant today, it takes it three years to break even. Three years may not be the exact number, but let’s use it for simplicity. Next year we finish two more plants, and the next year we finish four more plants. Regardless of whether the numbers are 1, 2, 4, or some other sequence, we need to build the increasing amounts if we’re going to get a lot of plants built. But notice this: the three-year break-even times start to overlap and pile up as we build more and more plants.
So? For any plant we build, we’re ahead after three years.
The net result is that we may not get much CO2 benefit from the solar plants until we are past the rapid-growth phase of building out new plants. If we go hell-bent for leather in building solar plants for the next 50 years or so, it is entirely possible that we won’t see much small benefit for 30 to 50 years.
Well, if we double the number of plants we build every three years we don’t get a net benefit until the end of the building phase. But that’s because we waited until the last three years to build half the plants. If we want the benefits sooner, we just have to build them sooner.
Myhrvold finishes with:
The point of the chapter in SuperFreakonomics is that geoengineering might be good insurance in case we don’t get global warming under control.
No, it isn’t. The point they are trying to make is that geoengineering is a more cost-effective solution than mitigation. Which is wrong. It might be cheaper, but you don’t get the same result.