Reducing CO2 Emissions: A Man-Kind Challenge

A little good news/bad news on the climate and energy front. In the Sept. 10 Science, Steven Davis and Ken Caldeira of Stanford University have a study that estimates what future carbon emissions—and consequent global warming—would be from existing energy and transportation infrastructure. (In other words, what would happen if we used all the current buildings and power plants and cars we have today to the end of their operational lifetimes, but built nothing new.) It's a useful thought experiment, and the results are somewhat cheering. Davis and Caldeira estimated that our current, almost completely fossil-fueled infrastructure would lead to an additional 496 billion metric tons of CO2 emissions between now and 2060, which would lead to an atmospheric CO2 concentration of less than 430 parts per million and a mean warming of 1.3 C above pre-industrial levels. If we could achieve those goals, it would be a major success for climate policy—international negotiators have generally looked to keep atmospheric CO2 levels below 450 ppm and warming below 2 C. As Davis and Caldeira write in their paper (done with the help of H. Damon Matthews from Montreal's Concordia University): "The primary threats posed by climate change are a consequence of emissions from devices that do not exist."

To put it simply, it's not the cars and other fossil-fuel burning devices that we've already built that will push warming to edge—it's everything we're likely to build in the future, as the globe's population and economy keeps growing. And that might be the bad news—it's obvious that we're not going to simply stop building new planes and power plants. That's especially true in rapidly growing developing nations like China, where the mean age of power plants is just 12 years (compared to 32 years in the U.S.). And existing infrastructure doesn't just mean cars on the road and coal power plants—highways networks with gas stations facilitate more cars, just as our network of oil refineries and drilling platforms facilitate the use of more oil. Changing all of that will be incredibly difficult—and it's getting harder every day.