A carbon tax is bad policy even if we assume the correctness of the IPCC’s climate sensitivity estimates and Obama-era EPA climate policy modeling.
In an op-ed published yesterday by CNS News, I explain why a carbon tax is not a conservative policy. The occasion for the piece is the debate stirred up by Rep. Carlos Curbelo (R-FL), who this week introduced a carbon tax bill euphemistically called the “Market Choice Act.”
At a press conference organized by Americans for Tax Reform where several conservative colleagues and I made an economic and political case against the Curbelo bill, a reporter asked for our views on climate science. If I’m not mistaken, the intent was to put us on the record as “climate deniers” to buttress the politically correct narrative that conservatives are “anti-science.”
In fact, you don’t need to be a climate skeptic or contrarian to oppose a carbon tax, and I can demonstrate that scientifically!
The most important issue in climate change research is climate sensitivity. That’s usually defined as how much long-term warming results from a doubling of carbon dioxide-equivalent greenhouse concentration. Scientists have been trying to estimate climate sensitivity since the late 19th century. There is still no “scientific consensus” on a specific value.
In its 2007 Fourth Assessment Report, the UN Intergovernmental Panel on Climate Change (IPCC) concluded that 3°C was the “best estimate” of climate sensitivity. However, because several subsequent studies estimated a lower sensitivity, the IPCC’s 2013 Fifth Assessment Report (p. 16) offered no best estimate. Rather, AR5 said climate sensitivity is “likely” to range from 1.5°C to 4.5°C. And guess what? That was also the likely range in the IPCC’s First Assessment Report in 1990 (p. xxv). The IPCC is no closer today than it was a quarter century ago to pinning down an exact value for the most important variable in climate change science.
Why mention this? During the Obama administration, the Environmental Protection Agency developed a climate policy impact estimator called “Model for the Assessment of Greenhouse Gas Induced Climate Change.” MAGICC allows us to calculate the decrease in average global temperature from any specific quantity of emission reductions under alternative climate sensitivity guestimates.
The Curbelo bill aims to reduce U.S. carbon dioxide-equivalent greenhouse gas concentrations 30-40 percent by 2030. So, plugging a 40-percent U.S. emission reduction into MAGICC, the world avoids a bit more than 0.01°C of global warming by 2050 if climate sensitivity is 1.5°C and somewhat less than 0.03°C if climate sensitivity is 4.5°C. You can crunch the numbers for yourself on the Cato Institute’s Carbon Tax Temperature-Savings Calculator.
So, even assuming high sensitivity, the Curbelo bill averts less than 0.03°C of global warming by 2050. That vanishingly small change is below NOAA’s 0.08°C margin of error for estimating changes in inter-annual global temperature. That means the Curbelo bill’s maximum climate impact is literally undetectable.