Source: Fraser Institute
by Ross McKitrick
The fact that CO2 emissions lead to changes in the atmospheric carbon concentration is not controversial. Nor is the fact that CO2 and other greenhouse gases (GHGs) absorb infrared energy in the atmosphere and contribute to the overall greenhouse effect. Increases in CO2 levels are therefore expected to lead to atmospheric warming, and this is the basis for the current push to enact policies to reduce GHG emissions.
For more than 25 years, climate models have reported a wide span of estimates of the sensitivity of the climate to CO2 emissions, ranging from relatively benign to potentially catastrophic. These continuing uncertainties have direct policy implications. Economic models for analyzing climate policy are calibrated using climate models, not climate data. In a low-sensitivity model, GHG emissions lead only to minor changes in temperature, so the socioeconomic costs associated with the emissions are minimal. In a high-sensitivity model, large temperature changes would occur, so marginal economic damages of CO2 emissions are larger. (more…)