Basically, you get a dT from the model, and that maps to some measurable impact (say, precipitation). You then make a function of that impact vs dT? Is that function linear, convex, concave, or depend on impact? And those functions vary little across model?
Then, since models might get different dT from different forcings, you are saying that it is the dT that matters not the way that you get there (emissions)? I guess aerosols will mess with this for some impacts?
And does this relate to what people call "pattern-scaling", which was an important part of the original SSP/RCP framework (Moss et al 2010). Sorry for the questions spread over multiple tweets (I guess email would have been better)...
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One of the key arguments that Norway uses to continue oil & gas developments, is that under BAU it is expected that oil & gas production will decline in line with <2°C scenarios, even with continued investment.
Let's look closer at these projections & reality...
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Here is the projections from the 2003 report from the petroleum agency.
In reality (tweet 1) there was a dip around 2010, but production is now up around 250 million cubic again.
The forecast was totally & utterly WRONG!
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In 2011 there was a forecast for an increase in production to 2020, but then a decline. This is probably since they started to put the Johan Sverdrup field on the books.
The increase in production was way too low, again, they got it wrong.
CO2 emissions by fossil fuel:
* We thought coal peaked in 2014. No, & up another 1.1% in 2023
* Oil up 1.5%, on the back of a 28% increase in international aviation & China, but oil remains below 2019 level. 🤞
* Has the golden age of gas come to an end thanks to Russia?
2/
By top emitters:
* China up 4.0% & a peak this year would be a surprise
*US down 3.0%, with coal at 1903 levels
* India up 8.2%, with fossil CO2 clearly above the EU27
* EU27, down 7.4% with drops in all fuels
* Bunkers, up 11.9% due to exploding international aviation
Is the new @DrJamesEHansen et al article an outlier, or rather mainstream?
At least in terms of the key headline numbers, it seems rather mainstream, particularly if you remember most headline key numbers have quite some uncertainty!
The Remaining Carbon Budget for 1.5°C is now smaller because: 1) We have not reduced emissions in three years 2) Updated simple climate models because of updated historical aerosol emissions 3) Some new method choices
The update for 2°C has similar changes for each component, but because the budget is much bigger, the changes don't seem that dramatic. Not Nature Climate Change worthy...
The changes to the 1.5°C budget seem dramatic, because the budget is basically gone.
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These updates are not new. A few years back 1.5°C was considered "geophysically impossible", but not after a revised budget:
I wrote a post on the utility of 1.5°C budgets back then, obviously ignored. Also on non-CO2.