I have run into a surprising number of people who think global warming has a good chance of causing an apocalypse that will destroy the world as we know it within the next few decades. I think that unlikely. We should be very concerned about the small chance that Earth could become like Venus, but in the long history of the Earth it has been very warm before, and it is not that likely that things will go completely off the rails this time.

Some of the biggest harms of global warming and the rise in atmospheric carbon dioxide riving global warming are likely to be:

1. effects on the ocean, including acidification

2. a combination of rising oceans and local climate changes that drives mass migrations that lack of sympathy for desperately poor “economic migrants” is likely to turn into humanitarian catastrophes

3. extinctions of many species

(Let me know what I forgot.)

Economists tend to favor a “carbon tax” on carbon dioxide emissions as a highly efficient and effective way to slow global warming. This kind of tax can also be applied to methane leaked into the atmosphere. Atmospheric methane is a powerful greenhouse gas, but also much, much shorter-lived than atmospheric carbon dioxide.

In their working paper “Making Carbon Taxation a Generational Win Win,” Larry Kotlikoff, Felix Kubler, Andrey Polbin, Jeffrey Sachs, and Simon Scheidegger argue that because many of the benefits of slowing global warming accrue to future generations, it is appropriate to rack up additional national debt—that future generations would have to deal with—if those funds are used to slow global warming.

Here is my favorite version of compensating the current generations for their efforts to reduce carbon dioxide emissions. I think once enacted, it could solidify political support for fighting global warming. Give all adult citizens an equal amount of transferable “carbon tax equities,” with additional equities created to give to children who reach age 18. These carbon tax equities would distribute the proceeds of carbon taxes in proportion to carbon tax equity holding. They would become worthless if carbon taxes were ever reduced to zero. So those who had bought up a lot of carbon tax equities would lobby strenuously against carbon taxes being reduced to zero, and could rightly claim it was unfair to do so when they had purchased the carbon tax equities under the expectation that there would be carbon taxes. Being given assets of substantial value, backed by carbon taxes for many years to come also makes it easier for people to finance an education or the purchase of a home.

Creating assets that help solidify a political settlement has important precedents. Alexander Hamilton argued (successfully) for the assumption of state debts by the new federal government because it would give bondholders a stake in the success of the new federal government. The Meiji government gave samurais “samurai bonds” to compensate them for their samurai stipend being cut off and allowed those samurai bonds to be used to capitalize banks. (There is a working paper on this: “Swords into Bank Shares: Finance, Conflict, and Political Reform in Meiji Japan,” by Saumitra Jha, Kris Michener and Masanori Takashima.)

What if we can’t get carbon taxes enacted in enough countries? In the Q&A after presenting “Making Carbon Taxation a Generational Win Win” at the 2019 North American Summer Meetings of the Econometric Society, Larry Kotlikoff said something fascinating: stopping the burning of coal alone can get one most of the way toward the benefits of an ideal carbon tax. Why is coal so bad? When combined with oxygen in the air by burning, every atom of carbon has the potential to make a molecule of carbon dioxide, and coal is almost entirely carbon atoms. By contrast, natural gas is mostly methane, CH4, which has four atoms of hydrogen for every atom of carbon. Oil is also a hydrocarbon, though it has a higher carbon to hydrogen ratio. The hydrogen atoms generate a lot of energy when combined with oxygen to form H2O: water. So there is a lot of energy from natural gas that isn’t coming from the carbon in it. In any case, burning coal is very, very bad—worse than burning natural gas, oil or other hydrocarbons. An international agreement to quit building coal power plants and to begin to phase out the existing coal plants would be a huge step forward for slowing global warming—a much, much bigger step than any international agreement so far to try to deal with global warming.

The horror of coal has an important implication for environmental activists: demonizing coal would do more than almost anything else they could do to save the planet. In my view, demonizing coal is quite possible if environmental activists focus on this goal. Inevitably if one tries to get across a dozen messages, each of those messages loses some punch. They can get lost among all the other messages. But if the horror of coal became the main message, I think people would remember. Demonizing coal seems quite doable because coal looks dirty. That is, coal is not only bad, it looks bad.

(I am not a big hashtag user on Twitter, myself but there are many tweets that bear the hashtag #killcoal. Here are some of my tweets with the words “Kill coal.”)

For those who are worried about apocalypse during their lifetime, let me give one more word of reassurance. climate engineering such as aerosols to block some fraction of sunlight may have bad side effects, but in a pinch they are quite doable. (See the Wikipedia article “Climate engineering.”) The cost is relatively modest. Moreover, unlike restraining carbon dioxide emission, for which it is crucial to get most nations on board, since a few big nations can emit a lot of carbon dioxide, climate engineering can be done unilaterally by one nation without any need of getting other nations on board. Bad things will happen in the world in the future, and many of those bad things in the future may result from global warming, but I think nuclear holocaust is a much more likely route to true “end-of-the-world”ish apocalypse than global warming.

Update, April 4, 2020: One of my students had some important questions about this post. Let me put my answers down on paper here.

First, what is an example of what I talk about in this passage?

... because many of the benefits of slowing global warming accrue to future generations, it is appropriate to rack up additional national debt—that future generations would have to deal with—if those funds are used to slow global warming.

The simplest case would be if some type of government purchases—say research spending—is important for slowing global warming. 

But what if a carbon tax is the main tool for stopping global warming? Then giving the current generation carbon tax rebates that are bigger than the current revenue from the carbon tax would be an example of racking up government debt to make it all a good deal for the current generation as well as for future generations. My proposal of carbon tax equities is in this spirit. 

Let me explain the carbon tax equities. "Equity" simply means something that works like a stock. Stock gives you ownership of a slice of a company's profits. Carbon tax equities are pieces of paper that give you a slice of carbon tax revenue. Just like stock, if you want, you can sell your rights to your future slice of carbon tax revenue. My idea is that the current generation gets the carbon tax equities. The value of these carbon tax equities is greater than the value of all the carbon taxes the current generation will pay, since the carbon tax equities include the value of carbon taxes future generations will pay. So the current generation is getting more back than it pays. This is arguably fair to future generations because they get a non-destroyed planet—it is in the interest of future generations to compensate/bribe the current generation to slow global warming.