Keep 1.5º C Alive
The Post looked at 1,200 possibilities for the planet’s future. These are our best hope. |
| The 2015 Paris agreement established the world’s most important climate goal: limiting the Earth’s warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) above preindustrial levels.
Keeping warming this low will help avert the most catastrophic consequences of unchecked climate change, such as dramatic sea-level rise that could inundate some small island nations, destruction of the Arctic’s protective sea ice layer, and the death of the world’s coral reefs. But achieving this target is now in grave doubt. Already, the planet has warmed by more than 1.1 degrees Celsius (2 degrees Fahrenheit) above preindustrial temperatures, while Russia’s invasion of Ukraine has complicated efforts to curb the use of fossil fuels, a primary driver of global warming. To see what hope remains, The Washington Post examined more than 1,200 scenarios for climate change over the coming century, drawing on models considered in a key report by the U.N. Intergovernmental Panel on Climate Change and working with experts from the Potsdam Institute for Climate Impact Research in Germany. The results reveal a world that keeps inching closer to climate catastrophe. But they also show that a safer future is still possible if humanity takes urgent, sweeping actions to phase out fossil fuels, electrify energy systems and remove carbon dioxide from the atmosphere, The Post’s Chris Mooney, Naema Ahmed and John Muyskens report this morning. If you have time, you can read our colleagues’ full story here. But if you’re in a hurry this morning, here’s a quick recap of how The Post crunched the numbers to determine what we can still do to meet the 1.5C goal: |
FILTERING OUT FRIGHTENING SCENARIOS |
| Our colleagues began by filtering out hundreds of scenarios that would not keep the 1.5C goal within reach. |
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| However, some of these remaining 230 scenarios rely on unrealistic assumptions, such as a dramatic decline in greenhouse gas emissions by 2025 or a massive build-out of nuclear power plants by 2030. |
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| That leaves just 112 paths that would keep the planet below 1.5C of warming by 2100. But some of these paths involve a “high overshoot,” in which warming soars above 1.5C before coming back down again.
Scientists say high overshoot is an unsettling prospect. It raises the possibility, for instance, of the Earth experiencing dangerous tipping points and even calamities such as the irreversible loss of the West Antarctic ice sheet, which by some estimates could increase global sea-level rise by about 3 feet. |
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| Therefore, our colleagues zoomed in on 26 scenarios that involve a “low overshoot” or none at all. To assess how realistic these 26 paths are, they used a method developed by the Potsdam Institute researchers to rate the scenarios as “speculative,” “challenging” or “reasonable,” in order of increasing plausibility. |
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| However, when our colleagues looked at only reasonable scenarios, they found that none of the paths would have low or no overshoot, while 16 of the paths would have a high overshoot: |
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| By contrast, when our colleagues looked at only challenging scenarios, they found 11 paths that involved low or no overshoot: |
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| Ultimately, these results suggest that the world has probably run out of easy options to stay below 1.5C or have low overshoot. But governments and corporations can still take steps that are more challenging — both scientifically and politically — to ensure a safer, cooler future. |
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| At the U.N. Climate Change Conference in Egypt last month, world leaders reaffirmed their commitment to “keep 1.5 alive.” Outside the conference venue, however, climate activists staged a demonstration where they pretended to resuscitate Earth.
It was an apt metaphor for a goal that is on life support but still reachable with dramatic action. |