World leaders are once again racing to avert disastrous levels of global warming through limits on greenhouse gas emissions. An agreement may be in reach, but because of the vast supplies of inexpensive fossil fuels, protecting the world from climate change requires the even more difficult task of disrupting today’s energy markets.
The White House last month released a blueprint to reduce United States emissions by as much as 28 percent by 2025. The plan lays the groundwork for the formal international climate talks this December in Paris, where the goal is a treaty on emissions that will seek to limit the rise in global temperatures to 3.6 degrees Fahrenheit above preindustrial levels. Beyond 3.6 degrees, scientists say, the most catastrophic climate consequences will occur, possibly including the melting of the Greenland ice sheet.
Forging a treaty in Paris would be no small task, yet would be just the beginning of a solution. The greater challenge will be deciding how much of the world’s abundant supply of fossil fuels we simply let lie. (Bill McKibben and more recently The Guardian have taken a maximal position in their Leave It in the Ground campaign.)
A huge excavator shoveled earth and brown coal near the Boehlen-Lippendorf power station in Germany in 2013. Credit Michaela Rehle/Reuters
To understand the scope of this challenge, I’ve tallied
the projected warming from fossil fuels extracted so far and the projected warming capacity of various fossil fuels that can be extracted with today’s technology. This accounting was done by taking the embedded carbon dioxide in each energy source and using a standard model for the relationship between cumulative carbon emissions and long-run temperature changes based on a 2009 Nature article. (More detail on the method is available here .)
For those who don’t like suspense, here’s the total: an astonishing 16.2 degrees. And here’s how that breaks down. Since the industrial revolution, fossil fuels have warmed the planet by about 1.7 degrees. We are already experiencing the consequences of this warming. In recent weeks, we have learned that the world had its warmest winter on record and that Arctic sea ice hit a new low, even as intense storms continue to inflict harm on communities globally.
Next, look at fossil fuel reserves, the deposits we know to be recoverable under today’s prices and technology. That is, they are inexpensive to access. If we were to use all of this coal, natural gas and petroleum, the planet would warm by an additional 2.8 degrees. Add the heat from those reserves to the 1.7 degrees from what has already been emitted, and you get a world that is 4.5 degrees warmer since the industrial revolution; this is beyond scientists’ recommended 3.6-degree threshold .
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