castanyes blaves

Random ramblings about some random stuff, and things; but more stuff than things -- all in a mesmerizing and kaleidoscopic soapbox-like flow of words.



Paul Krugman explains cap-and-trade

The textbook economics of cap-and-trade - Paul Krugman Blog -

I realized, after the last post, that it might be useful to write down just what the Econ 101 version of cap and trade looks like; as it happens, this also helps explain the intellectual sins of Glenn Beck and Martin Feldstein.

So here we go. Bear in mind that something like what follows can be found in just about every intro textbook.

Think of the benefits to the private sector from pollution. Yes, benefits — in the sense that it’s cheaper to pollute than not to, or that it’s easier to produce goods if you don’t worry about whatever emissions result as a byproduct. So we can think of drawing a curve representing the private marginal benefit of emissions, as in this figure:


In the absence of government action, the private sector will increase emissions up to the point where there is no further marginal benefit. That is, emissions will rise to whatever level is implied by profit-maximization, paying no attention to the effects on the environment.

A cap-and-trade system puts a limit on overall emissions, so that emitters have to pay a price for emitting. This price will, as shown in the figure above, equal the marginal benefit of the last unit of emissions allowed.

Now, the cost to the economy of this limit is the benefit the private sector would have gotten by emitting more than is allowed under the cap. It’s shown in the figure as the red triangle labeled “deadweight loss”. CBO puts these losses under Waxman-Markey at 0.2-0.7 percent of GDP in 2020, 1.1 to 3.4 percent in 2050. These costs have to be set against the environmental benefits.

In addition to this overall economic cost, there’s a distributional effect. The creation of cap and trade means that emission permits command a market price, and the value of these permits — the blue rectangle — goes to someone. Under Waxman-Markey, some of it (a growing fraction over time) would be captured by the government through auctions, and used to cut or avoid increases in other taxes — in effect, recycled to consumers. The rest would be passed on to industry — but because the biggest recipients would be regulated utilities, much of this would also be passed on to consumers.

OK, now let’s send in Beck and Feldstein.

Beck got his number from someone who learned about a guesstimate of what the auction value of permits might be (way higher than current estimates, by the way), divided by the number of households, and proclaimed this the cost of the bill. In effect, he looked at a guess about the size of the blue rectangle, which does not represent an economic cost, and called that the cost to the economy.

In a way, though, what Martin Feldstein did was worse. He took the CBO’s estimate of “compliance costs”, which was $1600 per household in an early report (it’s now down to $900, but who’s counting?), and implied that this was the economic cost of the legislation. But “compliance costs” are basically the sum of the blue rectangle and the red triangle; the true economic costs are just the triangle, and are much smaller.

Another way to say this is that under the Feldstein method, any time you try to correct an externality, which necessarily means changing relative prices, all of the negative effects of the price change will be counted as a cost — but none of the positive effects will be counted as a benefit.

Bad stuff. And what you should bear in mind is that all I’m doing here is conventional neoclassical economics, quite literally basic textbook material. What does it say when the people who claim to believe in this stuff throw it out the window as soon as it leads to policy conclusions they don’t like?


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