Three Quarters of the Planet's Fossil Fuels Must Stay in the Dirt, Scientists Say

Humanity is in a bit of an apocalyptic pickle—we've gotten all nice and used to burning coal and oil to keep our lights on and our cars chugging, but we're choking the skies with CO2 in the process. We've got more fossil fuels left to burn than the planet can stomach, and we know precisely how to get them. In other words, we're currently and certainly in the process of stringing up more than enough rope to hang our collective huddled selves with.

This concept—call it a carbon budget, the amount of CO2 we can burn before we risk collapse—isn't new. It was, famously, the focal point of environmentalist author Bill McKibben's viral Rolling Stone article "Global Warming's Terrifying New Math." There are nearly 2,800 gigatons worth of carbon left in the dirt, Bill wrote, if we want to stop from turning earth into a toaster oven, according to the best available science, we've got a budget of just 565 GtCO2.

Now, a team of climate scientists have gone back to the lab, and though the emerge with a slightly different number, the principle's the same—if we indulge our worser instincts, and burn through that sooty planetary stockpile, that's all she wrote. We've got to abstain from carbon-based fuels, and fast.

Over 27 scientists from the international community have backed a report titled "New unabated coal is not compatible with keeping global warming below 2°C," which essentially finds that building any new coal plants at all will push us past our carbon budget and push the planet to the brink. As in, no new coal power at all—unless the fumes are captured and stuffed underground in a highly infeasible process called sequestration.

"In Cancun, in December 2010 all countries agreed to keep global mean temperature increase from pre-industrial levels below 2˚C," the scientists write. That's the number that most climatologists finger as marking the tipping point; beyond that, ice sheets melt, permafrost thaws, and the feedback loops get nasty.

"To have more than 66% chance of remaining on this 2˚C pathway, the world can only emit a further 1050 GtCO2," scientists say. "This is approximately one-quarter of all known global fossil fuel reserves."

In other words, a full three-quarters of the planet's remaining coal, oil, and natural gas have to stay put or we risk runaway disaster. The authors argue that since oil is the hardest fuel to replace—it's so deeply entwined into our economy by way of petrol fuel and plastics—and natural gas is relatively clean-burning, coal is where we need to draw the line. It should be noted here that this is a gargantuan ask; coal is still on the up in China, India, and developing nations around the globe. Snuffing out those projects will be nothing short of a herculean feat.

The scientists also argue we need to cut coal out, and expand alternatives; solar and wind in particular. But more nuclear power, biomass, and geothermal power will be needed, too.

Otherwise we'll blow our cartbon budget, and 2˚C of temperature rise is inevitable. And it's all downhill from there.