How should we discuss scenarios of future emissions? What is the range of scenarios we should explore? These are constant issues in climate modeling and policy discussions, and need to be reassessed every few years as knowledge improves.
I discussed some of this in a post on worst case scenarios a few months ago, but the issue has gained more prominence with a commentary by Zeke Hausfather and Glen Peters in Nature this week (which itself partially derives from ongoing twitter arguments which I won’t link to because there are only so many rabbit holes that you want to fall into).
My brief response to this is here though:
Mike Mann has a short discussion on this as well. But there are many different perspectives around – ranging from the merely posturing to the credible and constructive. The bigger questions are certainly worth discussing, but if the upshot of the current focus is that we just stop using the term ‘business-as-usual’ (as was suggested in the last IPCC report), then that is fine with me, but just not very substantive.
References
- Z. Hausfather, and G.P. Peters, "Emissions – the ‘business as usual’ story is misleading", Nature, vol. 577, pp. 618-620, 2020. http://dx.doi.org/10.1038/d41586-020-00177-3
nigelj: Tipping points on sea level rise are not significantly relevant to CO2 levels
AB: They are immensely significant. Cities, suburbs, farms; lots of ‘stuff’ exist near sea level. All that ‘stuff’ needs to be protected, moved, or razed and replaced on higher ground. A single project, the North Sea dikes proposal that would run from Scotland to Norway and England to France, would take an entire year’s worth of the planet’s sand production. And what releases more CO2 and CH4 than the aftermath of a hurricane whose surge makes it past wetlands and dikes?
And since sea level rise is a generations-long thing and could max out at over 200 feet future folks will probably have to continue the retreat as the ocean advances. When ocean-front property lasts a tad longer than its mortgage “ownership” effectively turns into “renting” and “capital goods” become “disposable”.
________
Killian: I repeat: Nobody knows.
AB: Wow. I’m impressed. Not even gonna make a snarky remark about aliases.
________
AB: I was not speaking to you or about your precious baby.
Killian: Childish. Straw Man.
AB: You constantly insult me and most everyone else here, there, and everywhere. You ALWAYS instigate fights and then chastise folks for not kissing your ring. And now you’re butting into a conversation that has nothing to do with you and calling me childish for not focusing on you?? “Ef off” is quite the ‘adult’ response.
You’re so tone-deaf that you supplied evidence of your unacceptable behavior on another site!
Oh, and look up Straw Man. It is not synonymous with “Ef off”.
Al Bundy @101, regarding sea level rise requiring a lot of concrete work. By then low carbon cement and steel will be a reality. There are already promising low carbon cement technologies:
https://www.newscientist.com/article/2185217-the-future-with-lower-carbon-concrete/
But I have no answer to the methane issue. Still I think RCP8.5 looks untenable.
Look up “god complex” on wikipedia it describes some people perfectly (not you).
nigel, #97–
Replying belatedly; I had an earlier response, but apparently it didn’t go through for some reason.
But nigel, I didn’t even mention “tipping points on sea level rise!” Were you thinking of sea *ice*, which I did refer to?
Anyway, the point isn’t that the temperature at which the permafrost ‘tips’ changes, it is that getting there doesn’t require coal power for the whole ‘distance’ when there are multiple more-sensitive tipping points to do some of the ‘lifting’ instead of coal.
And no, I don’t believe that that is factored into the conclusion. If it were, and if I were the author, I sure wouldn’t state the tipping points in terms of temperature; I’d be talking about pathways and interactions.