Climate Change on the Back of an Envelope

Abstract:

A goal proposed by leaders in the climate movement is to restore atmospheric concentrations of carbon dioxide to 350 ppm by the end if the century and to limit climate warming to 2 degrees Celsius. Here, I simplify and analyze three topics relating to the feasibility of this goal: climate science, climate policy and climate solutions. 1) Climate system science is intricate, with unanticipated feedbacks and misunderstood lag times between causal events and their effects. Matthew and Zickfeld (2012) showed the effect of immediate zero emissions on global temperatures until 2200. This benchmark baseline is a "best case scenario" (though cutting emissions to zero tomorrow it is obviously not feasible) for limiting warming and restoring past climate. It helps us understand the minimum change we can expect from the climate system in the coming century. 2) Also quite complex is the climate policy scene, especially with unwieldy legislation like cap-and-trade that seeks to put a price on carbon by capping emissions. Here I explore one of the simplest and perhaps one of the most effective pieces of legislation proposed, a carbon tax with a revenue-neutral dividend. The tax starts at a substantial level and increases significantly each year until fossil fuels are phased out. Analysis from a Regional Economic Models, Inc. (REMI) study shows the impact of such a tax on forecasted emissions. Their results predict that this tax will significantly lower emissions by 2035. 3) Finally, proposed solutions are diverse and it is difficult to predict which ones will work best in the end. Jacobson and Delucci (2011) have shown that wind, water, and solar could replace fossil fuels in a little as two decades. I look at the feasibility of converting our energy supply (national and global) to renewables, and make simple estimates of the cost and time it would take to do so. This back-of-the-envelope analysis neglects interaction terms between climate science, policy and solutions, but provides a useful framework for anticipating policy action and inaction.