(This post first appeared on Climate 411.)
A nine-minute video, released earlier this fall, argues that climate mitigation is 50 times more expensive than adaptation. The claims are based on calculations done by Christopher Monckton. We analyzed the accompanying “sources and maths” document. In short, the author shows a disconcerting lack of understanding of climate science and economics:
- Fundamental misunderstanding of basic climate science: Pre-industrial levels of carbon dioxide (CO2) were at around 280 parts per million (ppm).[i] One of the most commonly stated climate policy goals is to keep concentrations below 450 ppm CO2. Monckton, oddly, adds 280 and 450 to get to 730 ppm as the goal of global stabilization efforts, making all the rest of his calculations wildly inaccurate.
- Prematurely cutting off analysis after ten years: Monckton calculates the benefits of the carbon tax over a ten-year time horizon. That is much too short to see the full effects of global warming or of the policy itself. Elevated carbon levels persist for hundreds to thousands of years.[ii]
- Erroneously applying Australian “cost-effectiveness” calculation to the world: This may be the most troubling aspect from an economist's point of view. Monckton first calculates the effect of the Australia-only tax on global temperatures, which is unsurprisingly low, as Australia accounts for only 1.2% of world emissions. Next, he calculates the tax’s resulting “cost-effectiveness” — defined as the Australian tax influencing global temperatures. No surprise once again, that influence is there, but Australia alone can't solve global warming for the rest of us. Then, Monckton takes the Australia-only number and scales it to mitigate 1ºC globally, resulting in a purported cost of “$3.2 quadrillion,” which he claims is the overall global “mitigation cost-effectiveness.” But this number simply represents the cost of avoiding 1ºC of warming by acting in Australia alone. Monckton has re-discovered the fact that global warming is a global problem! The correct calculation for a globally applied tax would be to calculate cost-effectiveness on a global level first. If Australia’s carbon price were to be applied globally, it would cut much more pollution at a much lower cost. And that, of course, is very much the hope. Australia, California, and the European Union are called “climate leaders” for a reason. Others must follow.
What’s the real cost of cutting carbon? The U.S. government’s estimate of the cost of one ton of CO2 pollution released today is about $40.[iii] That's also the optimal price to make sure that each of us is paying for our own climate damages. Any policy with a lower (implied) carbon price—including the Australian tax—easily passes a benefit-cost test.
With all due respect Lord Monckton, 3rd Viscount of Brenchley, your maths are way off.
[ii] Results differ across scenarios, but a rough rule of thumb suggests that approximately 70% of the ‘peak enhancement level’ over the preindustrial level of 280 ppm perseveres after 100 years of zero emissions, while approximately 40% of the ‘peak enhancement level’ over the preindustrial level of 280 ppm persevered after 1,000 years of zero emissions (Solomon, Susan, Gian-Kasper Plattner, Reto Knutti and Pierre Friedlingstein, “Irreversible climate change due to carbon dioxide emissions” Proceedings of the National Academy of Sciences 106, no. 6 (2009): 1704-1709). Note that this refers to the net increase in carbon dioxide in the atmosphere, not the exact molecule. Archer, David, Michael Eby, Victor Brovkin, Andy Ridgwell, Long Cao, Uwe Mikolajewicz, Ken Caldeira et al. "Atmospheric lifetime of fossil fuel carbon dioxide." Annual Review of Earth and Planetary Sciences 37 (2009): 117-134 discusses these two often confused definitions for carbon’s ‘lifetime,’ and concludes that 20-40% of excess carbon levels remain hundreds to thousands of years (“2-20 centuries”) after it is emitted. Each carbon dioxide molecule has a lifetime of anywhere between 50 to 200 years, according to the U.S. Environmental Protection Agency’s “Overview of Greenhouse Gases: Carbon Dioxide Emissions.” The precise number is under considerable scientific dispute and surprisingly poorly understood. (Inman, Mason, “Carbon is forever,” Nature Reports Climate Change 20 November 2008)
[iii] The precise value presented in Table 1 of the Technical Update of the Social Cost of Carbon for Regulatory Impact Analysis Under Executive Order 12866 for a ton of carbon dioxide emitted in 2015, using a 3% social discount rate increased is $38. For 2020, the number is $43; for 2030, the number increases to $52. All values are in inflation-adjusted 2007 dollars. For a further exploration of this topic, see Nordhaus, William D. The Climate Casino: Risk, Uncertainty, and Economics for a Warming World. Yale University Press (2013) as only one of the latest examples summarizing this kind of analysis. Nordhaus concludes that the optimal policy, one that maximizes net benefits to the planet, would spend about 3% of global GDP.
Many thanks to Michelle Ho for excellent research assistance.