Duluth, the New Jerusalem

William J. BernsteinBeyond abortion and immigration, few topics polarize Americans as much as climate change.

First, the facts: Around the turn of the last century, Swedish chemist Svante Arrhenius predicted that carbon dioxide (CO2) from the burning of fossil fuels would warm the planet. This didn’t worry him much, since he thought higher temperatures would improve crop yields and prevent an ice age recurrence.

Arrhenius’s conjecture elicited controversy, but not until the early 1960s did the combination of polar ice core samples and systematic monitoring of atmospheric CO2 on Hawaii’s Mauna Loa confirm his prediction; the ice core samples showed baseline CO2 concentrations averaging only 280 ppm, while the Mauna Loa samples measured atmospheric CO2 at 305 ppm – and rising rapidly. The most recent value stands at 425 ppm, and the central estimate of the temperature increase since the preindustrial period is 1.46oC, just short of the 1.50oC target of the Intergovernmental Panel on Climate Change (IPCC).

Since the half-life of atmospheric CO2 is 120 years, even the immediate elimination of all fossil fuel burning would take centuries to return the planet’s atmosphere to its preindustrial state. No such luck: Despite the rapid growth of wind and solar energy, we’re still dumping CO2 into the atmosphere at an ever-increasing rate: six gigatons of it in 1950, 20 gigatons in 1990, and 35 gigatons this year, at which level emissions are forecast to peak within the next year or two.

This is where the facts end, and conjecture begins.

Even the most optimistic estimates foresee an increase of about 2oC over preindustrial levels within a decade or two. While this is bad enough, the most pessimistic estimates run in the 6oC range over the next century, which would almost certainly prove catastrophic.