Article Fool us once: the effort to covertly bring RCP8.5 back to climate policy?

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https://rogerpielkejr.substack.com/p/fool-us-once

EXCERPTS: Yesterday’s New York Times featured an op-ed by David Wallace-Wells and Zeke Hausfather — a journalist and climate scientist respectively — both well-known for their commitments to climate advocacy. Normally, yet-another-apocalyptic-op-ed would not be worth commenting on, as they are a dime a dozen.

However, yesterday’s op-ed demonstrates how the new CMIP7 climate scenarios — discussed in detail here at THB — can be used to smuggle the implausibly extreme and retired RCP8.5 right back into discussions of climate science and policy. According to Hausfather, an IPCC AR7 lead author, the IPCC AR7 is going to adopt this strategy as well.

Misuse of RCP8.5 started early and snowballed from there, because no one corrected correctable missteps early on. We should not fall for this again.

The op-ed starts off well enough, asserting accurately: "Projected future warming has fallen quite a bit, and a worst-case emissions scenario known as “RCP8.5” - in which coal use would roughly quintuple by 2100 - is being phased out as implausible."

The op-ed then takes a sharp turn. Wallace-Wells and Hausfather claim: "A new round of forecasts from the climate science community is pretty alarming."

There are no new “forecasts” from the “climate science community.” The IPCC has always carefully explained that it does not forecast the future — appropriately so. It produces projections conditional on scenarios.

Further, the results of earth system model research with such conditional projections incorporating the new scenarios are still a ways off. An assessment of the “climate science community” will have to await the IPCC AR7. 

[...] "The high-end warming sometimes described as a 'worst-case scenario' remains very much on the table, too."

That last sentence is a not-so-subtle reference to the climate outcomes that emerged from the retired RCP8.5. How can it be that RCP8.5 is being “phased out” yet its implications remain ”very much on the table”?

Below I show how RCP8.5 is being brought right back into the discussion of climate science and policy via a Trojan Horse that carries a misuse of scenario extensions... (MORE - missing details)

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While I find 'The Honest Broker' to be a intelligent commentator I'm not entirely sure of his honesty particularly when it comes to climate change.

can be used to smuggle the implausibly extreme and retired RCP8.5 right back into discussions of climate science

I have neither the will nor the time to follow Pielke down every rabbit hole he finds but I suspect he's found something that works for him that, as far as I can make out, is unrelated to the actual CMIP7.. to the extent that the only person trying to smuggle the retired  RCP8.5 back into discussions is Pielke himself.

CMIP7’s high scenario comes in remarkably lower [than RCP8.5]  at 3.3C (2.6-4.4C) [in 2100].

The downward revision of future emissions in CMIP7 reflects two key changes since RCP8.5 was published back in 2011. First, the plausible baseline of a repeal of current policy has fallen. Cheap solar, wind and batteries, a global plateau in coal use and more than $2tr per year in clean-energy investment mean that a rollback in climate policy would not result in coal deployment levels assumed in the RCP8.5 scenario.

More details .. https://www.carbonbrief.org/explainer-th...ate-change