Der Spiegel: How German Electricity Became A Luxury Item.

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9. How Much Global Warming Is Guaranteed Even If We Stopped Building Coal-Fired Power Plants Today?

How Much Global Warming Is Guaranteed Even If We Stopped Building Coal-Fired Power Plants Today?

Humanity has yet to reach the point of no return when it comes to catastrophic climate change, according to new calculations. If we content ourselves with the existing fossil-fuel infrastructure we can hold greenhouse gas concentrations below 450 parts per million in the atmosphere and limit warming to below 2 degrees Celsius above preindustrial levels—both common benchmarks for international efforts to avoid the worst impacts of ongoing climate change—according to a new analysis in the September 10 issue of Science. The bad news is we are adding more fossil-fuel infrastructure—oil-burning cars, coal-fired power plants, industrial factories consuming natural gas—every day.

A team of scientists analyzed the existing fossil-fuel infrastructure to determine how much greenhouse gas emissions we have committed to if all of that kit is utilized for its entire expected lifetime. The answer: an average of 496 billion metric tons more of carbon dioxide added to the atmosphere between now and 2060 in "committed emissions".

That assumes life spans of roughly 40 years for a coal-fired power plant and 17 years for a typical car—potentially major under- and overestimates, respectively, given that some coal-fired power plants still in use in the U.S. first fired up in the 1950s. Plugging that roughly 500 gigatonne number into a computer-generated climate model predicted CO2 levels would then peak at less than 430 ppm with an attendant warming of 1.3 degrees C above preindustrial average temperature. That's just 50 ppm higher than present levels and 150 ppm higher than preindustrial atmospheric concentrations.

Still, we are rapidly approaching a point of no return, cautions climate modeler Ken Caldeira of the Carnegie Institution for Science's Department of Global Ecology at Stanford University, who participated in the study. "There is little doubt that more CO2-emitting devices will be built," the researchers wrote. After all, the study does not take into account all the enabling infrastructure—such as highways, gas stations and refineries—that contribute inertia that holds back significant changes to lower-emitting alternatives, such as electric cars.

http://www.scientificamerican.com/article.cfm?id=guaranteed-global-warming-with-existing-fossil-fuel-infrastructure