SSP3 is the nightmare climate scenario that keeps scientists up at night. A good look into one of the worst possible future outcomes for society by @blkahn featuring @leahstokes and myself: earther.gizmodo.com/the-nightmare-… 1/10
In the lead-up to the 2021 IPCC 6th Assessment report, energy system modelers have developed five different "Shared Socioeconomic Pathways" of population, GDP, technological innovation, and cooperation that the world could follow: carbonbrief.org/explainer-how-… 2/10
SSP3 is the worst of these: a rocky road of regional rivalry characterized by resurgent nationalism, isolationism, persistent or even growing inequality, high population growth, and slow global economic growth. 3/10 
Its a world where each country puts its own interests above all, where countries return to domestic energy resources like coal. Its a world of high barriers to both climate mitigation and adaptation. 4/10
Why does this scenario keep me up at night, rather than the higher emissions (and somewhat higher warming) SSP5 scenario? A few reasons: 5/10
First, climate is a threat multiplier. A world with fragile systems and regional conflicts is one where climate impacts are more likely to result in societal collapse than a highly prosperous, equal, and technologically advanced SSP5 world 6/10
(as an aside, why in a highly prosperous, equal, and technologically advanced countries would decide to stick with coal and increase its use 500% – as in the SSP5 baseline – is more than a bit bizarre). 7/10
Second, adaptation matters. A relatively equal world is one where high levels of warming will still be quite bad, but one where countries like Bangladesh can respond much better to sea level rise, more intense tropical cyclones, or disruptions in crop yields than today. 8/10
I don't think we are necessarily on a SSP3-type pathway today, though ascendant populist movements in the US, Brazil, and the UK are certainly not a promising sign. If we want any hope of achieving Paris Agreement goals we need to go down a different pathway. 9/10
Current policies are leading us toward a world of around 3C (+/- 1C) warming by 2100, as global coal use plateaus and falls. Thats by no means the worst case outcome; if populism and isolationism dominate the rest of the 21st century we could be looking at a much worse future. 10
