Nearly All the Unburned Coal Must Stay in the Ground to Avert Climate Catastrophe

A new study quantifies the vast amount of fossil fuels we need to leave untouched if we want to stave off the worst impacts of warming.

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Photo: Matthew Brown (AP)

It’s becoming more and more clear that hobbling the fossil fuel industry and getting the world to decarbonize as rapidly as possible is our best hope at staving off the most catastrophic impacts of warming. A new study finds that we need to keep nearly all the world’s coal reserves and more than half its oil and gas in the ground if we want to keep warming under 1.5 degrees Celsius (2.7 degrees Fahrenheit).

“Dramatic cuts in fossil fuel production are required immediately in order to move towards limiting global heating to 1.5 degrees,” Dan Welsby, the lead author of the report and researcher at University College London, said at a conference on Tuesday. “But the current and indicated fossil fuel production trajectories globally are moving us in the wrong direction.”

The study, which was published Wednesday in Nature, uses models of global “unburnable” carbon. Those are basically fossil fuels that simply can’t be burned if we want to meet the goals of the Paris Agreement. The models take into account the differences in carbon intensity in fuels in different parts of the world. Canada’s tar sands, for instance, have a much bigger carbon footprint than other types of fuels.


The research is actually an update of a similar study done in 2015, right before the world met in Paris to hammer out details for the international agreement. In that study, researchers looked at what would be needed to keep warming under 2 degrees Celsius (3.6 degrees Fahrenheit), finding that 80% of coal, 30% of oil, and 50% of gas needed to be kept in the ground to keep heating below that threshold that eventually became enshrined in the Paris Agreement. In addition, the agreement also included the 1.5-degree-Celsius target as a more ambitious goal that also happens to be life and death for many small island nations.

The new numbers in this updated study are pretty stark. Of the coal still in the ground around the world, a whopping 90% needs to stay there if we want to keep warming under the 1.5-degree-Celsius threshold. Almost 60% of the world’s oil and gas reserves, meanwhile, also needs to be kept in the ground. Overall, the study found that global production needs to go down by a rate of around 3% per year through 2050.


And because different areas of the world have different intensities of carbon in the reserves of fuel they still have in the ground, each region has a different homework assignment, so to speak, in terms of making sure the world doesn’t burn to a crisp. Canada has a huge job on its hands in wrangling in the oil industry: The study found 83% of its oil reserves, including 84% of tar sands, need to stay in the ground. Meanwhile, the Middle East’s oil target is closer to the 60% global average. But that number being lower than Canada’s doesn’t mean the region won’t feel the squeeze as much; on the contrary, the study warns of “huge transition risks” for countries with economies solely focused on fossil fuel extraction.

The conclusions in this study echo the growing consensus among experts that we need to get the world off dirty fuels as quickly as possible. Earlier this year, the International Energy Agency said that fossil fuel production needs to peak next year if we want to stick that 1.5-degree-Celsius target. This study gives a similar, if even more stringent, mandate: Global fossil fuel production overall technically should have peaked last year to keep us on track with the Paris Agreement targets.


Oil production specifically has a little bit more wiggle room. The peak should be 2025, the study found, while gas’s peak depends on location. Regardless of the dates, the decline of fossil fuels needs to be nigh. Yet the industry is pursuing expansion aggressively, and there remains a so-called “production gap” with the world producing more fossil fuels than what’s safe. But as the new study shows,dramatic changes need to happen—and soon.