One of the more engaging critics of the Waxman-Markey ("cap-and-trade") bill that the House approved on Friday is Jim Manzi, whose work appears in a bunch of places like The National Review, and The American Scene. The economics of both climate change itself and policy efforts to mitigate it are murky, problematic areas and Manzi deserves credit for trying navigate the waters honestly -- it's nice to be engaged in a debate with a conservative who doesn't seem to think that Al Gore invented global warming.
One of Manzi's central points is that climate change just ain't all that damaging, economically speaking: it will reduce global GDP by "only" 5 percent one hundred years hence, he writes, even arguably pessimistic assumptions by the IPCC about both the magnitude of climate change and its economic impacts. There are a couple of economic points that can be raised against this, the most persuasive of which has to do with the possibility of "fat tail" events like warming of 10-20 degrees C, which appear unlikely based on present knowledge but which cannot entirely be ruled out, and which would effectively destroy the world economy if not civilization itself. There's also the question of what happens after 2110, because if we've reached that point by 2110, it means that things almost certainly will continue to get worse, not better.
Most of all, though, I wonder if GDP is really the right measure at all. This is not a qualitative objection against looking at things through an economic lens: it is, rather, a merely technical one.
The problem with GDP is this: it varies greatly across counties, by a factor of 800 or so on a per-capita basis between Burundi and Luxembourg, or nearly 2,000 if you count Zimbabwe, which effectively does not have an economy. A lot of countries contribute almost nothing to global GDP, even though they may have tens or hundreds of millions of people. You could literally wipe them from the globe and the impact on global GDP would be de minimis.
Why don't we try and do that, in fact? Let's see how much of the world we can destroy before getting to 5% of global GDP. The figures I'll use are IMF estimates of 2008 GDP, for all countries bit Zimbabwe where the IMF did not publish a 2008 estimate and I use 2007 instead.
Zimbabwe, indeed, is the first country on the chopping block, whose 11.7 million greedy bastards consume a whole 0.0196 percent of the world's output -- a global low of just $55 per person. After that, we get to destroy Burundi, The Congo (the larger of the two Congos -- the one that used to be called Zaire), Liberia, Guinea-Bissau, Eretrea, Malawai ... do you really me to go through the whole list? You do? ... Malwai, Ethopia, Sierra Leone, Niger, Afghanistan (big problem solved there), Togo, Guinea, Uganda, Madagascar, the Central African Republic, Nepal, Myanmar, Rwanda, Mozambique, Timor-Leste, the Gambia -- we've only used 0.27 percent of GDP to this point, by the way -- Bangladesh (which has 162 million people), Tanzania, Burkina Faso, Mali, Lesotho, Ghana, Haiti, Tajikistan, Comoros, Cambodia, Laos, Benin, Kenya, Chad, The Soloman Islands and Kyrgyzistan. Next up is India, which, while growing, still consumes only 2 percent of world GDP. Then Nicaragua, Uzbekistan, Vietnam, Mauritania, Pakistan (another problem solved), Senegal, São Tomé and Príncipe, Côte d'Ivoire, Zambia, Yemen, Cameroon, Djibouti, Papua New Guinea, Kiribati, Nigeria (another pretty big country -- we've now got only about 1.4 points of GDP left), Guyana, the Sudan, Bolivia (our first foray into South America), Moldova, Honduras, the Philippines, Sra Lanka, Mongolia, Bhutan and Egypt.
At this point, we've used up 4.4 points of GDP. Indonesia is next on the list of lowest per-capita GDPs. But unfortunately we can't quite fit them into the budget so we'll spare them, opting instead for Vanauatu, Tonga, Paragua, Morocco, Syria, Swaziland, Samoa, Guatemala, Georgia (the country -- not the place where they have Chik-Fil-A), the other Congo, and Iraq. Skipping China, we then get to Armenia, Jordan, Cape Verde, the Maldives -- and another big bunch of skips follows here since we're very low on budget -- Fiji and finally Namibia. Collectively, these countries consume 4.99997 percent of the world's GDP. There's absolutely no budget left for anyone else -- not even St. Vincent and the Grenadines, which would be a great band name, BTW.
So, we'll have to settle for just these 81 countries, which collectively have a mere 2,865,623,000 people, or about 43 percent of the world's population.
Still, that's not too bad for a day's work. We've gotten rid of almost all of Sub-Saharan Africa, destroyed the entire Indian subcontinent, created a big lake in South America, turned El Salvador into an island, and solved a lot of our problems in the Middle East. I suspect we could also have nuked North Korea, by the way, except that the IMF didn't publish information for them.
Coincidentally, or not, a lot of these countries are located in the tropics, where global warming would probably have its most pernicious effects. True, they would probably not be entirely eradicated even under some of the worst-case, fattest-tail climate change assumptions. But if you reduced their GDPs by, say, 40 percent, it would look like mere rounding error on the world scene.