Keeping the increase in global temperatures under 2°C will require vast amounts of fossil fuels to be kept in the ground, including 92 percent of U.S. coal, most of Canada’s tar sands, and all of the Arctic’s oil and gas, according to the first analysis of which of the world’s reserves should remain untapped.
The study, published in the journal Nature, is a stark assessment of how resource-rich nations and regions will have to adjust to the reality that the battle against climate change means abandoning huge sources of their wealth. Limiting the increase in worldwide temperatures to 2°C (3.6°F) above pre-industrial levels is generally agreed to be what is necessary to prevent dangerous climate change.
“Our results suggest that, globally, a third of oil reserves, half of gas reserves, and over 80 percent of current coal reserves should remain unused from 2010 to 2050 in order to meet the target of 2°C,” write authors Christophe McGlade and Paul Ekins of University College London.
The bracing analysis of what needs to left in the ground comes less than a year before a UN climate summit in Paris next December to complete a global agreement on limiting emissions. It is based on existing estimates of fossil fuel reserves and their global warming potential and economic models of market forces related to which fuels are the most cost effective. It assumes that, with carbon emissions limited, cheaper fuels will be used first, with higher priced fuels left unexploited.
“We’ve now got tangible figures of the quantities and locations of fossil fuels that should remain unused in trying to keep within the 2°C temperature limit,” McGlade told The Guardian. To keep warming below 2°C, worldwide emissions between 2011 and 2050 would need to be limited to 1,100 gigatons of carbon dioxide. Estimated fossil fuel reserves contain about three times that much carbon.
The study projects that the use of coal, the dirtiest fuel, would face the most severe constraints, with the U.S., Australia, and the former Soviet Republics leaving 90 percent or more of it in the ground. In the U.S., most of our oil and gas reserves could be used. In the Middle East, significant shares of the region’s oil and gas reserves would have to be left untouched.
Ekins told The Guardian that the study calls into question the huge sums that energy companies are spending on locating new sources of fossil fuels. “In 2013, fossil fuel companies spent some $670 billion on exploring for new oil and gas resources. One might ask why they are doing this when there is more in the ground than we can afford to burn.”
Or as 350.org co-founder Bill McKibben put it: “One lesson of this work is unmistakably obvious: when you’re in a hole, stop digging.”