Majority of remaining fossil fuels must stay in the ground to limit climate crisis: study

An Extinction Rebellion climate change activist holds a banner backdropped by the Bank of England, at left, and the Royal Exchange, centre, in the City of London financial district, on Sept. 2, 2021. (Matt Dunham / AP)

To avoid the worst consequences of climate change — worsening extreme weather, irreversible ecosystem shifts, loss of life and economic hardship — scientists say the world must limit global warming to 1.5 degrees Celsius above pre-industrial levels. The only way to do that, they say, is by making deep cuts to fossil fuel emissions.

New research quantifies exactly what it would take: keeping a vast majority of Earth's remaining fossil fuels tucked underground.

The study, published in the journal Nature on Wednesday, found that nearly 60% of the planet's remaining oil and natural gas and 90% of its coal reserves should remain in the ground by 2050, underscoring that most regions around the world must reach peak fossil fuel production now or within the next decade to avoid the critical climate threshold.

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"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 Tuesday news conference. "But the current and indicated fossil fuel production trajectories globally are moving us in the wrong direction."

Researchers say the model accounts for real-world constraints — namely, the speed at which global economies can move away from fossil fuels — that pushed their result to the very limit of a 50% chance to stave off the worst climate change impacts.

To achieve a higher probability of staying below 1.5 degrees, even more carbon needs to stay on the ground, researchers said.

Scientists have already said that only by making rapid, severe cuts to greenhouse gas emissions, while simultaneously removing carbon from the atmosphere, can we halt the precipitous warming trend. The authors also noted that their findings may be an underestimate, since their model doesn't consider future Earth system feedbacks, nor does it take into account underlying uncertainties around the deployment of technologies needed to curb emissions.

"An option is to really start decarbonizing now, rather than either plateauing global emissions or increasing them," James Price, co-author of the study and research associate at the University College London, told CNN. "We need to decarbonize as fast as possible to improve our chance of staying below 1.5 degrees."

Fossil fuels account for more than 80% of the global energy consumption, but scientists say their production would need to go down substantially. Welsby and his colleagues at the University College London say that many operational and future fossil fuel projects are "unviable" and "not conducive" to reaching international climate targets.

Oil and gas production, according to the study, need to decline by 3% each year until 2050 to meet the goals of the Paris Agreement, signalling severe implications for producers who are banking on continued profits from fossil fuel production.

For coal, Welsby said, all regions need to have already reached peak production — a promising sign since global coal production peaked in 2013, though many countries still rely on the fuel. For oil, all regions should be peaking now or by 2025, according to the study. For gas, researchers say the outlook varies depending on the region.

"We found that in parts of Europe, the U.S. and Russia and the Caspian, gas production needs to peak now," Welsby said. "This production decline is offset by increased production to the 2030s in the Middle East, Africa and other parts of developing Asia. The majority of this increased production in those regions is due to robust domestic demand growth, particularly in power generation and industry."

The study makes one thing clear: fossil fuel investments made today risk being stranded in the future as the climate changes.

As countries get serious about addressing the climate crisis, Steve Pye, a co-author of the study, said that the economics of such investments are "going to start looking increasingly problematic."

"There are key transition risks, driven by falling demand due to the increase in clean energy technologies," he added, "and also increased pressure on production-based activities themselves by investor in shape of shareholder activism or new legislation."

According to a 2020 report by the Stockholm Environment Institute and the UN Environment Programme, despite establishing targets to make strict and significant cuts to greenhouse gas emissions, countries are actually projecting an average increase in fossil fuel production of 2% annually.

Scientists say that needs to change immediately. The countries with the largest fossil fuel reserves have the largest global influence to limit climate change. Canada, for example, has a much higher reserve — 83% — that needs to remain in the ground by 2050 than other regions.

Meanwhile, all oil-producing regions — except the U.S. — will see strong declines in production leading up to 2050. The U.S. won't peak until 2025, according to the study, before declining due to plummeting oil imports and the continued use of fossil fuels in the transportation sector.

"The takeaway in this study really addresses the elephant in the room," Maisa Rojas Corradi, coordinating lead author of the major UN report on climate change, but was not involved with the study, told CNN.

"We have known since we've signed up for the Paris Agreement in 2015, that this means we have to stop burning fossil fuels by mid century," she said. "For six years, we have known the logical consequence is that there are loads of fossil fuels that would not be able to extract. It's really good that the paper shows so clearly what, in very practical terms, this really means."

The study builds on an earlier paper published in 2015, which estimated that more than 30% of oil reserves, nearly 50% of gas reserves and more than 80% of coal reserves should not be extracted by 2050 in order to stop careening toward planet warming of 2 degrees Celsius higher than pre-industrial levels.

The latest estimates in the new study revealed higher numbers and assesses reserves out to 2100 under a 1.5-degree scenario. The findings show shares of fossil fuel reserves — 58% for oil, 59% of natural gas and 89% of coal in 2050 — considered economic today would be unextractable under a global 1.5-degree target.

Despite what is required to avoid critical climate changes, researchers say countries still have a long way to go, which means that immediate action is necessary. In doing so, Pye said that fossil fuel producers and investors need to realize that further extraction is no longer suitable for the planet. Developed nations also need to help those that are still industrializing to halt the trend.

"There's a lot that developed countries can do to help support a just transition," Pye said. "And that's the only way that we're going to get buy-in from a broader range of countries to actually diversify economies away from oil and gas."