Sure - here’s the key quote, and a lot of the meat is in the links:
But people should know that we’ve gotten a lot of good news about RCP 8.5 over the past few years. Think about every optimistic climate story you’ve ever read: the falling cost of solar power, improvements in lithium-ion batteries, surging sales of electric vehicles. Even closures of coal plants under economic pressure from cheap natural gas — a fossil fuel that, while not exactly clean, is definitely cleaner than coal.
The upshot of all of this is that future industrial development is on track to be cleaner than past industrial development, even without any new policy changes or technological breakthroughs. Is it on track to stabilize global emissions and limit warming to 1.5 degrees Celsius? It is not. But we can pretty confidently say that scenarios that just project the past upward emissions curve forward are very unlikely. For that to happen, we’d need a huge resurgence of the coal industry and for every single auto company in the world to be somehow wrong about electric cars.
But this extreme scenario is actually very unlikely. The current International Energy Administration energy market projections suggest we’re on track for two to three degrees Celsius of warming (median forecast of 2.2 degrees). This is bad, which is why world governments agreed to a lower target. But it’s a lot less than the warming involved in scenarios where “those living in coastal areas from Texas to New England … will face dramatic increases in hurricane-driven flood risk as the Earth heats up.”
The “almost certainly” part is an inference from what Yglesias describes as what would have to happen for us to go back to the RCP 8.5 scenario - not just stopping where we are now, but going back to massive coal production and undoing all the price reductions in solar panels and wind turbines and everything. That’s just not going to happen. We’re “almost certainly” never going to land on the RCP 8.5 trendline, which is what motivated him to decry the continued references to RCP 8.5 in climate alarmism discussion.