A modest proposal for resolving our differences on CO2.

There are no solutions. There are only trade-offs.[Thomas Sowell

I belated realized the obvious. A person’s effective SCC is the mean of his

SCC probability density. Duh!

Figure 1. Germany's trade off curve if the overnight cost of nuclear is $8000/kW

Your effective Social Cost of CO2 (SCC) is the slope of the grid cost-CO2 tradeoff curve at the point on that curve that best balances the harm of CO2 versus the consumption of the planet's resources for you. In other words, you have an effective SCC whether or not you admit it. In an earlier episode, we found (to his surprise) that Jack has an effective SCC of about $200/ton, and Alice's effective SCC is $800/ton.

The Gordian Knot Group has used its Grid Model, to come up with a set of CO2/grid cost trade off curves for Germany, varying the cost of nuclear power. Figure 1 shows the German tradeoff curve for a nuke overnight cost of $8000/kW. Underlying each point on that curve is the combination of wind, solar, coal, gas, nuclear, batteries, and hydrogen that produced that point.

Your preacher has sermonized at length on the social cost of CO2 making two points:

1) While nobody can be sure what her/his SCC is, that need not paralyze us nor force us to assume a very high SCC no matter how unlikely that SCC is. Even if you are explicit about your uncertainty about CO2, you do have an effective SCC. If you are a full on Bayesian, the mean of your SCC probability density is your effective SCC.

2) Very different feelings about the social cost of carbon can lead to rather similar electric grids. Of course, this only happens if we start with the trade off curve, decide where the best point/compromise on that curve is, and only then ask what combination of electricity sources produces that grid.

Some people have it completely backwards. They pick a grid and live with whatever CO2 and grid cost that grid produces. Usually, they are not on the trade off curve, and often far above it. There is a word for this bassackwards process. Stupid. And since this stupidity effects others, it is also criminally immoral.

Figure 2. CO2 (black line) from 10 to 25 thousand years ago. LGM is Last Glacial Maximum.

But nobody in the choir is that stupid, so we can move on to the next complication. Everybody's SCC depends on the amount of CO2 already in the atmosphere. Suppose we were all transported back to the end of the Last Glacial Maximum, 18,000 years ago. Atmospheric CO2 is hovering around 190 ppm, Figure 2, the lowest ever in 4.5 billion years. That's about 15 ppm above the level needed to support photosynthesis.

The more excitable among us would don red habits and scream extinction is nigh. And they would be right. It’s only 15 ppm away. The rest of us would be complaining: man, it's really cold. Glaciers are everywhere. Nothing is growing very well and you can't grow anything on ice.

I submit everybody's SCC at the time was negative. Suppose some genius invented something he called a "coal plant". This wonder produced an entirely new form of energy called electricity. But far more importantly, for every ton of coal burned it produced 3 tons of CO2. Some other genius came up with something she called a "nuclear plant". It produced 100,000 times more electricity from a ton of fuel than a coal plant, and therefore consumed far less resources. It was a lot cheaper. But her problem was it produced almost no CO2. Her invention faded into obscurity.

As the amount of CO2 in the atmosphere increased, the value of additional CO2 decreased, and at some point additional CO2 began to be viewed as on-net harmful. Everybody's SCC changed.

Assuming we don't want to be criminally stupid, our only differences are different effective SCC's; and it turns out those are fluid. It seems we don't have that much to argue about. So here's my plan:

1) We figure out what the trade off curve is, and publish the curve. That's a purely technical job, requiring no value judgements. We don't disclose the grid behind each point on the curve.

2) We take a binding poll, asking everybody what point on the curve they like best.

3) The median of the answers is declared the societal optimum.

4) We reveal the grid that produced that point. And that's the grid we build.