(NaturalNews) The only way to avoid catastrophic climate change is to stop burning coal entirely, leaving a full three-quarters of the planet's fossil fuel reserves untouched, according to two studies published in the journal Nature.
Scientists around the world have warned that any rise in average global temperature greater than two degrees Celsius (2C) from pre-industrial times would result in worldwide catastrophe. Temperatures have already risen by 0.7 degrees since the industrial revolution, and are expected to rise at least as much again even if all fossil fuel use is stopped today.
While more than 100 countries have committed to averting a 2C or greater rise, they have adopted an approach of setting caps on the amount of greenhouse gases that may be emitted in any given year. Myles Allen of Oxford University warns that this is the wrong approach.
"To avoid dangerous climate change, we will have to limit the total amount of carbon we inject into the atmosphere, not just the emission rate in any given year," he said. "Climate policy needs an exit strategy; as well as reducing carbon emissions now; we need a plan for phasing out net emissions entirely."
According to an analysis by Allen and colleagues, total carbon dioxide emissions of one trillion tons would push the world over the 2C mark.
"It took us 250 years to burn the first half trillion, and on current projections we'll burn the next half trillion in less than 40 years," he said.
A second study concluded that gradual reductions in emissions like those being pursued by most nations are unlikely to avert climate catastrophe.
"Only a fast switch away from fossil fuels will give us a reasonable chance to avoid considerable warming," said researcher Malte Mainshausen of the Potsdam Institute. "If we continue burning fossil fuels as we do, we will have exhausted the carbon budget in merely 20 years, and global warming will go well beyond 2C."
Mainshausen and colleagues concluded that only 25 percent of known fossil fuel reserves can be burned without exceeding the 2C mark. This would mean leaving all remaining coal reserves unburned.