The most consequential number
Nordhaus shared the 2018 Nobel for work he had been doing since the 1970s: integrating climate science with growth to calculate the optimal cost of decarbonization. His central finding: the most important variable is not the temperature target. It is the discount rate — the rate at which you value future welfare relative to present welfare. Change it by two percentage points and the entire prescription flips. Most people have never heard of the discount rate. It may be the most consequential number in the history of the species.
We accept the scientific consensus entirely. Our contribution is the prescription. And the prescription begins with a question the other camps treat as obscene: how much should we spend, and when?
Germany’s Energiewende cost over 500 billion euros and produced electricity prices double the European average, while emissions declined less than the UK’s. France decarbonized its grid in fifteen years using nuclear power — faster than any renewable-only strategy. A carbon tax rising predictably over thirty years gives every firm a price signal to decarbonize at the pace the economy can absorb. A regulatory mandate that demands immediate transformation produces Yellow Vest protests.
The moral emergency camp tells us our math is missing the moral weight. Moral urgency without calibration produces the Energiewende — enormous cost, modest result, political exhaustion. The adaptation realists understand cost-benefit. But adaptation without mitigation is a treadmill — you build the seawall for today’s sea level and the sea keeps rising.
Where we concede ground: The discount rate is a moral choice wearing a technical costume. Nordhaus at 4 percent values a 2100 life at a fraction of a 2024 life.
What would change our mind: A comprehensive carbon tax at our recommended level producing significantly less emissions reduction than projected after fifteen years.
Read the full synthesis: Is climate change a science problem, an economics problem, a moral problem, or something else?