Illustration for article titled The Nightmare Climate Scenario That Keeps Scientists Up at Night
Photo: Kena Betancur (Getty)

Imagine a world fractured into rival factions, countries distrustful of one another and unwilling to cooperate. Nationalism is on the rise with authoritarianism on the horizon. Inequality is also climbing, and the resource curse is alive and well. Rich countries plunder poorer ones, leaving behind a wave of environmental degradation, all so consumers can have material-intensive bric-a-brac. Conflict is a constant specter.

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That’s basically Earth in 2020. The Trump administration has put the U.S. into, if not a war, a heightened conflict with Iran (or is continuing an endless war in the Middle East, if you prefer that rosy view). Fascist and nationalist political parties have risen in popularity and even taken power in some countries including Brazil, Italy, Germany, and Austria. Immigrants in the U.S. are scorned, caged, and departed. An entire country is basically on fire.

This is the hellscape of modern life. But it’s also the basis of a scenario climate researchers began working on modeling in the early 2010s as part of a project to help decision-makers better understand the potential contours of the 21st century. The uncomfortably prescient project resulted in five Socioeconomic Shared Pathways (SSPs for short), and the bleakest is SSP3. The scenario paints what, in typically understated fashion, scientists have called a “rocky road,” one where the world can’t be bothered to stop climate change or adapt to it, creating a worsening cycle that could send humanity and the climate to a very dark place.

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Scientists have modeled the future climate for more than a century. Models began with a pretty simplistic set of equations and have evolved over time to include more and more variables to capture the kaleidoscope that is the climate. But some of the biggest breakthroughs in recent decades have included us in that kaleidoscope.

Humans have poured carbon pollution into the atmosphere, and we’re now the dominant driver of the climate present and future in many ways. Models used in the most recent big United Nations climate reports have included some underlying assumptions about society, though they’ve mostly focused on how much heat-trapping carbon pollution we end up putting in the atmosphere. But another effort took a somewhat different approach and over the last decade developed the SSPs as a kind of climate-adjacent modeling effort. Their goal was used to craft a few overarching visions of global society and then see if those modeled societies could meet the emissions targets in the climate models. Basically, it’s one big, nerdy model-slam designed to help us better understand the biggest questions facing humanity over the 21st century.

Amidst the scenarios, SSP3 easily stands out as the most dire. Zeke Hausfather, an energy analyst at Berkeley Earth and author at Carbon Brief who wrote an amazing primer on the SSPs, told Earther it’s the scenario that keeps him up at night.

“The narrative of SSP3 scares me [because] it envisions a world where our nation-states are much less stable and prosperous,” he said.

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Here are just some of the narrative researchers wrote up to describe SSP3 in a 2015 paper (emphasis theirs):

“A resurgent nationalism, concerns about competitiveness and security, and regional conflicts push countries to increasingly focus on domestic or, at most, regional issues. This trend is reinforced by the limited number of comparatively weak global institutions, with uneven coordination and cooperation for addressing environmental and other global concerns. Policies shift over time to become increasingly oriented toward national and regional security issues, including barriers to trade, particularly in the energy resource and agricultural markets... A low international priority for addressing environmental concerns leads to strong environmental degradation in some regions. The combination of impeded development and limited environmental concern results in poor progress toward sustainability. Population growth is low in industrialized and high in developing countries. Growing resource intensity and fossil fuel dependency along with difficulty in achieving international cooperation and slow technological change imply high challenges to mitigation. The limited progress on human development, slow income growth, and lack of effective institutions, especially those that can act across regions, implies high challenges to adaptation for many groups in all regions.”

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Hausfather called our current world “SSP3-ish,” particularly the rise of populism. Leah Stokes, an energy policy researcher at the University of California, Santa Barbara, told Earther that in some ways “beginning to wake up to much of what SSP3 captures, which is fascism and nationalism and erecting of border between places.”

Research linking this vision with society and the climate paints a bleak picture. Findings show there’s no scenario in which society achieves the Paris Agreement goals of limiting warming to 2 degrees Celsius (3.6 degrees Fahrenheit) under SSP3. And the 1.5 degrees Celsius (2.7 degrees Fahrenheit) goal is but a pipe dream if the world continues its march to fragmentation and lack of cooperation. Hausfather said because of this and computing limitations, the next Intergovernmental Panel on Climate Change report will only model SSP3 in conjunction with a high emissions scenario since it’s the most likely outcome.

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“It’s a world where, to be honest, there are a lot more pressing concerns other than climate change because it’s a world riven by conflict and instability,” he said.

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While the modeling effort doesn’t include the effects an unraveling climate would have on those issues, it’s not hard to imagine a vicious cycle of climate causing societal deterioration, which in turn causes climate deterioration, which in turn causes societal deterioration, on and on.

“Money is going to be a scarcer resource going forward,” Stokes said. “We are going to need to put human capital and financial capital into remaking the entire economy. That is not endless.”

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Without the resources or the will to adapt to a hotter planet, Stokes said she worries it would lead to a world organized around “lifeboat ethics,” a racist concept coined by ecologist Garrett Hardin of “tragedy of the commons fame. The idea is, as the lifeboat starts to take on water, you push some people over the edge to stay alive. And as our current world illustrates, poor people, communities of color, and others with fewer means or without white skin are usually to the first to go over the gunnels.

“This is a potential outcome that is developing,” she said. “It’s very sad because it’s not what we were all taught as children or what the world’s great religions tell us about people who are suffering.”

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But just because we’re at the start of the rocky road doesn’t mean we have to keep walking down it. There are five SSPs and countless paths that cut between them. SSP1 is what scientists have dubbed a “green road” that tilts toward a sustainable development pathway where governments work together to conserve common good resources, wealth is shared more equally, and people buy less crap. That scenario opens the door to meeting the 1.5 degrees Celsius goal. SSP2—the “middle road” scenario—is a bit less optimistic and people still use fossil fuels; but with enough sound climate policy, even that scenario gets us to a safe climate in most model runs.

Thinking about offramp to those scenarios feels a bit vertigo-inducing. This is the start of a critical decade that will go a long way toward deciding what society and the climate look like for the rest of the century. Right now, it feels like we’re driving 180 mph down the SSP3 highway. The climate strike movement, small island states, dire scientific warnings are all working to tap the brakes.

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“From social movements, you see yearning for more equality in the world,” Stokes said. “That’s a way of pushing back against this darker timeline of climate.”

But for those movements and humanity to have a chance, the only way to slam the pedal down and exit safely is more force pushing against humanity’s destructive momentum.

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Managing editor, Earther

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