Grasping Reality on TypePad, by Brad DeLong

Aha. A friend has sent me a scan of what he calls the "particularly egregious" pages 186-7 of Steve Levitt's and Steve Dubner's Superfreakonomics: Global Cooling, Patriotic Prostitutes, and Why Suicide Bombers Should Buy Life Insurance:

Indeed, I find that I have six questions for them about these two pages:

1: "Wood notes that the most authoritative literature on the subject suggests a rise of about one nd a half feet by 2100..." I had thought that the most authoritative estimates suggest a 1 to 7 feet rise in sea levels by 2100--not 1.5 feet. Am I wrong?

2: "Ken Caldiera... mentions a most surprising enviromental scourge: trees..." I grant that covering the reflective greenland ice sheet with green leaves might not be a good idea. But surely Ken Caldeira of Stanford did not say that your average tree is doing less to cool the earth by sucking up carbon dioxide than if the tree were cut down and decomposed and some other more-reflective typical use were made of its spot, is he?

3: "Then there's this little-discussed fact about global warming: while the drumbeat of doom has grown louder over the past several years, the average global temperature during that time has in fact decreased..." As best as I can see from http://data.giss.nasa.gov/gistemp/graphs/Fig.A2.txt, this year is:

• 1/5 of a degree F warmer than last year
• the same temperature as 2007 and 2006
• 1/7 of a degree F cooler than 2005
• 1/10 of a degree F warmer than 2004
• the same temperature as 2003 and 2002
• 1/7 of a degree F warmer than 2001
• 2/5 of a degree warmer than 1999 and 2000
• the same temperature as 1998
• and warmer than every single other year since the start of the Industrial Revolution--a full degree F warmer than 1960, for example.

How do you get from that temperature record to the statement that "over the past several years... average global temperature... has in fact decreased"?

4: "coal is so cheap that trying to generate electricity without it would be economic suicide..." That coal is cheap does not mean that moving away from it would be "economic suicide." That depends on (a) how large a share of total costs are energy costs, and (b) how expensive the long-run alternatives to coal turn out to be. And that is what we are trying to figure out. What definition of "economic suicide" are you using?

5: "The problem with solar cells is that they are black... designed to absorb light from the sun.... But only about 12 percent gets turned into electricity, and the rest... contributes to global warming." Surely the heat energy reradiated from a solar panel is a small fraction of the heat trapped by all the carbon dioxide that would be produced by the coal-fired plants that would otherwise generate the electricity, isn't it?

6: "The energy consumed by building the thousands of new solar plants necessary to replace coal-burning and other power plants would create a huge long-term 'warming debt'." I had thought that practically none of the power plants that we will use in 2050 are now in operation, and that building them--whether for open-carbon cycle, closed-carbon cycle, or non-carbon--will cost about the same amount of energy, and thus that there is no significant extra power-plant construction debt from going green in our new power-plant construction over the nezt forty years as long as it is done gradually. Am I wrong?