SAN FRANCISCO — Maybe your old truck isn't responsible for destroying the planet after all.
New climate change scenarios quantify the idea that oil is only a small component of the total global warming problem — the real problem is coal.
If the world replaced all of its oil usage with carbon-neutral energy sources, ecologist Kenneth Caldeira of Stanford University calculated that it would only buy us about 10 years before coal emissions warmed the planet to what many scientists consider dangerous levels.
"There's an order of magnitude more coal than oil. So, whether there is a little more oil or a little less oil will change the details in, say, when we reach two degrees warming, but it doesn't change the overall picture," Caldeira said Wednesday at the American Geophysical Union annual meeting.
Many of the efforts to "green" our world's infrastructure have focused on the importance of changing the world's transportation systems. Indeed, one of the images of environmental destruction is the car-choked freeways of Los Angeles — and hybrid vehicles like the Toyota Prius have become a badge of environmental pride.
But as the latest projections show, when it comes to global warming, oil is a bit player on a stage dominated by the massive amounts of coal burning, particularly in the United States and China.
"If we want to change the overall shape of the global warming curve and instead of having it go up, stabilize and eventually go down, we need to deal with coal," Caldeira said.
The real global warming culprit — as James Hansen and his colleagues at NASA's Goddard Institute for Space Studies have long argued — is burning coal to generate electricity.
"Oil and gas by themselves don't have enough carbon to keep us in the dangerous zone [of global warming] for very long," said Pushker Kharecha, a scientist and colleague of Hansen at NASA GISS.
While both Kharecha and Caldeira stopped short of saying that the world's oil usage didn't matter, Caldeira seemed to capture their joint sentiment when he called the combustion of oil a "second-order effect."
Liquid fuels are so relatively insignificant that no matter what, nothing we put in our cars is likely to change the basic story of climate change. Even if oil ran out tomorrow and humans began converting coal in its solid form to a liquid you could put in a car — a worst-case scenario for environmentalists — the global warming contribution of that fuel is almost negligible.
Caldeira calculated that swapping out oil for liquified coal would only push the world to dangerous levels of global warming two years earlier than the world's best business-as-usual estimates. Either one is dwarfed by the carbon dioxide emissions from traditional coal burned for electrical generation and industrial production.
"I don't want to say it's not important what we do to replace oil. And this is where I'm being policy prescriptive: It would be far better to replace it with renewables than with coal liquefaction," Caldeira said. "But the big problem is the huge amounts of coal that we're likely to burn this century and release into the atmosphere in the absence of policy."
It's clear: The King of Global Warming Problems is King Coal.
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