In 2018 William Nordhaus became a co-recipient of the Nobel Memorial Prize in Economic Sciences for his work on attempting to integrate climate change issues into mainstream economics. He began studying this problem back in the early 1990s, when acid rain and the ozone hole were a bigger public concern than greenhouse gas emissions.
The Spirit of Green is quite effectively written in that it clearly conveys Nordhaus' ideas, and so this review will mostly focus on the actual ideas themselves. He finished writing the book as COVID-19 closed in around us all, and so he chose to add some thoughts about the need for governments to act in emergency situations. Strangely, he refrains from talking about any economic issues related to pandemics. A couple of obvious topics would have been to what extent governments should provide financial support to individuals and businesses affected by pandemic restrictions and the cost and availability of new vaccines.
Nordhaus advises government preparedness to meet emergencies such as future pandemics and appropriate government intervention. But his writing about climate change itself doesn't seem to even remotely suggest that this issue should itself perhaps be treated as an emergency right now. He is certainly no neoliberal, but, as a self-professed neoclassical economist, he constrains himself to stay within the limits of his professional outlook. His recommendation to apply a carbon tax to “internalize the externality” has still not been applied in his own country, the US, and has mostly been applied only rather modestly in some other countries. Yet he comes across as patiently optimistic. Perhaps he is encouraged by the fact that government intervention in North America and Europe did prompt technological innovation that significantly reduced acid rain and that a global banning of CFCs reduced the ozone hole. He must hope that a similar result will eventually reduce greenhouse gas emissions ideally on a global scale.
If Nordhaus feels any frustration at this much slower response to curtailing greenhouse gas emissions, it never comes out in the book. In fact, he exorts business and individuals not to try to cut back too much, but only enough to just cancel the cost to society of each additional ton of carbon dioxide emitted. One reason he is so calm is that he firmly believes in the concept of substitution of goods. This is all very well for, say, the creative destruction of the VCR business in favour of DVD technology. But irrevocable damage to the planet isn't really creative destruction, and it's unclear what technological gadgets will make up for the loss.
So, what is the right price to put on a ton of carbon dioxide? Nordhaus explains very smoothly the benefits of simply putting a price on the emissions to signal the actual environmental cost. It all sounds so easy, rational, straightforward. Perhaps the most reasonable thing is to start off with a price that business and consumers will accept and then crank it up over time. That way, you use it as a signal for society as a whole to find ways to shift away from fossil fuels over time, without claiming to know what the correct price is. Nordhaus occasionally hints at this, although he mostly seems convinced that there is a correct price. He often mentions the (now slightly dated) US government estimate of $40 per ton of carbon dioxide, which was actually calculated using a version of Nordhaus' DICE model.
But, even if you have a good handle on the actual future costs of adding greenhouse gases to the atmosphere now, the present value is strongly dependent on the discount rate. This is a meaningful enough concept if you are thinking of lending money to someone who you hope will repay it to you in ten or so years time, but what does it mean to discount the future value of the climate for your or anyone else's grandchildren?
Nordhaus talks about a pollution Laffer curve. The standard Laffer curve is meant to show that if you tax economic activity too highly, that activity will cease altogether and you will receive no tax revenue. Nordhaus focusses a lot on the revenue generating capabilities of a carbon tax, without clarifying how he thinks this revenue should be spent. If it is going to be vital for stimulating a Green New Deal initiative, then it is important to actually raise sufficient revenue. But if it is primarily meant to be a signal for all of us to find ways to shift away from fossil fuels, then surely it doesn't matter if it increases over time to become such a prohibitive penalty that it serves to ban certain activities altogether. Who cares that it raises no revenue if it has done its job?
Nordhaus steers well clear of so-called tipping points. He does mention fat-tailed probabilities in a general hand-waving way, but he never comes right out to admit that no minor adjustment to today's economy will help if we are actually moving towards the possibility of massive methane emissions from melting tundra, or a significant destabilization of the Greenland or Antarctic ice sheets. Come to that, even the minor (in geophysical terms) melting of the Himalayan glaciers will not be a minor issue to the millions who depend on them as a primary source of water. Is $40 per ton supposed to cover that?
Since Nordhaus first started thinking about these issues thirty years ago, considerable progress has been made in renewable technologies such as solar and wind, but the large-scale adoption has been miserably slow. Nordhaus is brutally realistic when he states that, even if carbon taxes were applied globally to his complete satisfaction, there is no chance that we will keep the global temperature rise within 2º C, and little chance that we will stay within 3º degrees for that matter. There are other more inspirational economists who propose more radical ideas, such as Kate Raworth's doughnut economics. Raworth and others are ultimately attempting to change the global zeitgeist in order to move us all towards a truly sustainable mode of economic behaviour. This is absolutely necessary but it is also (if one is to be even mildly realistic) hard to imagine it ever happening. Meanwhile, it surely doesn't hurt to have someone like Nordhaus try to nudge the more reactionary members of society to accept some sort of cost structure for what has become the most omnipresent economic externality of them all.