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8.5°C Disaster Scenario Misses Decarbonization Trend, UBC Researchers Conclude

Lydia Jacobs/Public Domain Pictures

Apocalyptic scenarios of 8.5°C average global warming by 2100 are overstated because they fail account for the historical trend of adopting energy forms with ever lower carbon intensities, from coal, to oil, to natural gas, to renewables, concludes a new study in the journal Environmental Research Letters.

In fact, state Ph.D candidate Justin Ritchie and Prof. Hadi Dowlatabadi, of the University of British Columbia Institute for Resources, Environment and Sustainability, the worst-case RCP8.5 scenario published by the Intergovernmental Panel on Climate Change assumes “a ‘re-carbonization,’ as coal’s influence overpowers much-reduced emissions from oil and gas.”

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The analysis adds up to “good news,” writes Bloomberg Environment correspondent Eric Roston, but “we are still in a lot of trouble.”

For Ritchie and Dowlatabadi, “the basic issue has to do with coal,” Roston explains. “Quite simply, the more we burn, the faster we destroy the atmosphere.” That reality led the IPCC to produce RCP8.5 as “one of four siblings. Their names, from bad to worst, are RCP2.6, RCP4.5, RCP6.0 and RCP8.5. They were introduced in 2011 as a way for researchers running different climate-economic models to do comparable studies regarding how high greenhouse gas concentrations might rise by 2100.”

The endgame of a planet cooked at 8.5°C has been useful to scientists because “it focuses the mind on the unthinkable and how to avoid it,” he writes. But the new research indicates that the “unthinkable” is actually off-the-charts improbable, given that “the amount of greenhouse gases emitted as a result of using energy—called the carbon intensity of energy—has been slipping for decades.”

That conclusion is still good news for policy-makers, Roston adds, because learning that “current goals of reducing coal, oil, and gas consumption may be closer than we think” should encourage climate analysts and negotiators “to set the bar even higher in our efforts to reduce pollution.”

And set the bar higher we must, he warns. “Global average temperatures have already risen almost 1.0°C in the past century. The 1.5°C goal may already be impossible, and 2.0°C would require major emissions reductions and, later this century, technological advances to pull enough carbon out of the air.”

Detlef van Vuuren, senior researcher at the Netherlands Environmental Assessment Agency and lead author of a 2011 overview  [2]of the RCPs, cautioned against taking the 8.5°C scenario off the table. “Just because something has become unlikely doesn’t mean it’s impossible, and given the stakes of climate change, it’s best to be thorough,” he told Bloomberg.

Ultimately, writes Roston, “there are no crystal balls, particularly on the timelines which govern climate-economic models. It’s not impossible that societies will return to coal in the way they are now fleeing it, particularly if population growth continues apace and technological aspirations fall short.”

Senior research scholar Bas van Ruijven of the International Institute for Applied Systems Analysis noted that three “new generation” scenarios demonstrate “continued decarbonization—and not a return to the coal bonanza.” But he cautioned that “humans are very hungry for energy. If renewables hit a wall, oil and gas dry up, and we punt forever on climate change, we might well be excavating all the coal we can put our hands on.”