Meeting a Global Carbon Limit Is Cheaper Than Avoiding One

http://www.scientificamerican.com/article/meeting-a-global-carbon-limit-is-cheaper-than-avoiding-one/?WT.mc_id=SA_SP_20151123

By Michael E. Mann on December 1, 2015

•••••

Yet some critics have declared that the so-called 2° C target is impossible, saying we cannot deploy the technologies needed to decarbonize the economy in time. But we can. The obstacle is not a physical one—it is one of political and societal will.

Nobody has said it will be easy. More than 70 climate experts who advised the U.N. Framework Convention on Climate Change said limiting global warming to below 2° C “necessitates a radical transition … not merely a fine tuning of current trends.”

•••••

According to one recent analysis, staying below 2° C would require that a third of all proved reserves of oil, half of all natural gas and 80 percent of coal remain in the ground.

•••••

The 2° C threshold is often equated with keeping the atmospheric concentration of carbon dioxide below 450 parts per million (ppm). The challenge is made tougher as we use less coal. When it burns, coal releases sulfate aerosol particulates into the atmosphere that reflect some of the sun's incoming energy back into space. For a 2014 Scientific American article, “False Hope,” I calculated that to compensate for the drop to zero sulfur emissions by the end of the century, we have to meet a CO2 target of about 405 ppm—just slightly above current levels.

[Note that carbon dioxide lasts a lot longer in the atmosphere than aerosol particulates. So the cooling effect of sulfate aerosol particulates is temporary.]

•••••

The key factor is that there are technological innovations and economies of scale that emerge only in the course of actually doing something. The price of solar cells globally, for example, has dropped by more than 50 percent over the past several years as China has ramped up production. Those who say “no we can't” are engaging in self-fulfilling prophecy. The U.S. has never been a nation of no-we-canters.

•••••

The cost of taking action is only half as much as the cost of inaction. This is not the conclusion of the Intergovernmental Panel on Climate Change. It comes from ExxonMobil, which has pegged the true cost of carbon to society at $60 a ton. Other estimates are even higher. Can we afford to stabilize planetary warming below two degrees C? We can't afford not to.

•••••