I'll be interested of course in how the IPCC WG1 treats scenarios but also, those reporters on the climate beat who are very well aware of these issues
Implausible scenarios of scary, alarming, extreme futures are often too enticing not to report on as predictions/projections
As I explained in The Climate Fix a decade ago, the core messages of the IPCC have remained largely unchanged since 1990, and I expect those messages to be reaffirmed by AR6 ... probably with better graphics and images
Those looking for radically new messages will be disappointed
We should expect the IPCC to face criticism from two directions
There will be some who say that climate change is a hoax (much fewer of these folks nowadays)
And others who complain that it is too conservative, scientists are cowed or reticent (lots more of this around now)
The IPCC is in many respects self-regulating as it depends upon an existing literature
If it were to depart from that literature it'd get called out
Of course sins of commission (see AR4 glaciers 2035) are easier to see than sins of omission (see AR3 Pielke et al 2005)
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🧵Some things to watch for in tomorrow's IPCC report:
➡️Are 7.0/8.5 used as ref scenarios?
➡️Has central est of climate sensitivity gone up/down vs AR5?
➡️Does report venture into policy (eg, carbon budgets, Paris Agreement, etc)?
➡️Does D&A framework get tossed in favor of EA?
Importantly
AR6 WG1 will necessarily be less "alarmist" than AR5 (which wasn't that alarmist) simply bc RCP8.5 was centered in AR5 and we now know extreme scenarios (7.0/8.5) are implausible
Expect lots of excuses from IPCC observers for again focusing on extreme scenarios
I fully expect a lot of euphemisms to be used tomorrow for "reference scenario"
Like:
➡️high emissions scenario
➡️very high emissions scenario
➡️worst case scenario
➡️continued increasing emissions
Changing semantics won't change the underlying issues w/ implausible scenarios
🧵Some might be curious why the IPCC focuses on the scenarios that it does
After all these scenarios are the foundation of the entire report's look to the future & assessment of possible impacts and the worth of different policy approaches . . .
The short answer is that the highest priority scenarios were selected for scientific purposes first & considerations of plausibility absent
Here is how the CMIP6 exercise justified its baseline (BAU/reference) scenarios
This is a bit of an loaded question, since CMIP6 prioritized 7.0/8.5 scenarios (baseline aka BAU aka reference) so we should expect these to serve as reference scenarios (euphemisms: "high emissions," "4 deg C" or "emissions continuing to increase") in AR6
We shall see . . .
Does anyone know if full AR6 is released Monday or just SPM? I'd hope the whole thing
The science of advantage in both Pistorius & Leeper cases was substantially similar, notably the presence of an advantage could not be determined conclusively in either case (uncertainty & dueling experts!)