Climate Economist Defends Extreme Scenario: 'Still Thinkable'

Nebojša Nakićenović, an Austrian energy economist, is defending his 2011 RCP8.5 climate scenario, which has become a focal point in debates about climate change severity. While some climate researchers now deem it implausible, Nakićenović insists that such extreme outcomes cannot be ruled out.

"I would not rule out such an extreme climate scenario," Nakićenović stated in an interview with DIE ZEIT. He believes it is still conceivable that real-world developments could take a tragic turn, leading to catastrophic levels of emissions. He is currently attending a conference on climate neutrality at Tsinghua University in Beijing.

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No. On the one hand, I would not rule out such an extreme climate scenario. It is unfortunately still conceivable that the real development takes a tragic course.

Opponents of strong climate action, ranging from political figures to the US president, have leveraged the RCP8.5 scenario to challenge climate scientists, accusing them of fabricating data and engaging in alarmism. However, Nakićenović argues that these high-emission scenarios are vital tools.

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On the other hand, these high-emission scenarios are needed to test climate models and to figure out how we can adapt to climate change.

"These high-emission scenarios are needed to test climate models and to figure out how we can adapt to climate change," he explained. He stressed the irresponsibility of not exploring the consequences of emissions reaching catastrophic levels, which could destabilize Earth systems and trigger further societal crises.

Nakićenović co-developed RCP8.5 for the UN's Intergovernmental Panel on Climate Change, aiming to cover the full spectrum of future possibilities, including high emissions. The scenario, which assumes no climate protection measures, projects a world population of twelve billion by the end of the century with minimal economic growth, and a tenfold increase in coal use alongside a tripling of CO₂ concentration. He emphasized that the scenario was based on extensive scientific literature assessment, not arbitrary invention.

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But it would be irresponsible not to explore what will happen if emissions reach a catastrophically high level and give us a climate in which all sorts of parts of the Earth system tip over. And with them, societies get into many more crises.