Zeb Nicholls

Researcher @unimelb's @ClimateCollege. None of what I do or say on here is my employers’ fault.

[Zeb Nicholls @NichollsZeb]

THREAD

CMIP5 and CMIP6 data

Find the idea of downloading terrabytes of data to extract a global-mean signal from CMIP scary? Our new paper will help!

https://t.co/NHRjPLjVWD https://t.co/KDKqV9VOc2

[Matthew Gidden @mattgidden]

🚨Our new paper is out in @Nature! 🚨

We assess how key global mitigation benchmarks shift after aligning pathways assessed by the @IPCC_CH to LULUCF accounting conventions used by parties to the #ParisAgreement.

Open access and available at: https://t.co/1cEXV5SlHF

[Zeb Nicholls @NichollsZeb]

@openclimatedata @meinshausen Thanks to @bobkopp for the comments

[Zeb Nicholls @NichollsZeb]

@openclimatedata @meinshausen 'nobody is using pdfs' bahaha

I feel seen, I always use pdfs for my reviewer comments

[Zeb Nicholls @NichollsZeb]

@Peters_Glen very good, very very good

[Zeb Nicholls @NichollsZeb]

@Peters_Glen Your idea!

[Zeb Nicholls @NichollsZeb]

@LeonSimons8 @HMcJeon3y4 @RobinLamboll @Peters_Glen Pretty much (same as anything, my GCM doesn’t represent clouds, so I’ll parametrise them and calibrate as best I can given what my model does capture). Maybe we find it the models don’t have the detail to capture the effect in a good way, that would also be interesting

[Zeb Nicholls @NichollsZeb]

@RobinLamboll @LeonSimons8 @HMcJeon3y4 @Peters_Glen Yes but it requires careful setup

[Zeb Nicholls @NichollsZeb]

@RobinLamboll @LeonSimons8 @HMcJeon3y4 @Peters_Glen MAGICC has some ability to track the impact of emissions in different regions, but it’s a four box model so it’s nowhere near as detailed as a GCM. As @RobinLamboll has said elsewhere: good enough for quick estimates, not the detail of an ESM (or sat obs or whatever else)

[Zeb Nicholls @NichollsZeb]

@JKikstra @HMcJeon3y4 Everyone’s solar cycle (fair, hector etc all have the same thing) but yes

[Zeb Nicholls @NichollsZeb]

@Peters_Glen @openclimatedata @EdwardByers My answer is we should go digging on all of them (and add uncertainties in to see how it looks with a sense of scale), but in a world of constrained resources some things get more focus than others. Maybe one day we’ll have teams whose only job is monthly model updates?

[Zeb Nicholls @NichollsZeb]

@Peters_Glen @openclimatedata @EdwardByers Ah, I was trying to find it in the GUI. Hopefully the AR6 climate diagnostics|* output makes more sense/is more consistent, but definitely N2O re-examination is on the list

[Zeb Nicholls @NichollsZeb]

@Peters_Glen How did you make the picture on the right? There's no N2O concentration data in the publicly available set in the AR6 database as far as I can see, am I missing something?

[Zeb Nicholls @NichollsZeb]

Good that someone is thinking about this, but I can’t help thinking, ‘How does this compare to the cost of not transitioning?’

[Peter Zeniewski @PZeniewski]

How much will it cost for the world to transition coal? That’s the trillion dollar question. At the @IEA, we did a detailed assessment of every coal plant in the world, and all the coal used in industry, to make some estimates. Let’s ‘dig’ in...

[Zeb Nicholls @NichollsZeb]

@HMcJeon3y4 @JoeriRogelj Could be done but you’d have to be nervous about using it outside of its calibration range because you’ve got no physics to bound the behaviour

[Zeb Nicholls @NichollsZeb]

@LeonSimons8 @HMcJeon3y4 @_david_ho_ There are some emissions uncertainties in there, but yes hard to tell exactly which and maybe not all the ones you’re thinking of

[Zeb Nicholls @NichollsZeb]

@HMcJeon3y4 @LeonSimons8 @_david_ho_ I believe they are too (very hard to get the low end of the range if you’re not including climate uncertainty)

[Zeb Nicholls @NichollsZeb]

@HMcJeon3y4 My understanding of theory of knowledge isn’t good enough to answer with confidence, but a quick google suggests yes, it’s the uncertainty associated with underlying model structure and the ability to represent the true processes (?)

[Zeb Nicholls @NichollsZeb]

@HMcJeon3y4 Also worth looking at how big the magicc update bar is compared to a) total uncertainty and b) in temperature terms (it’s roughly 0.05K). So yes, it’s the dominant term in the figure, but all the terms are small relative to other uncertainties (eg historical warming uncertainty)

[Zeb Nicholls @NichollsZeb]

@HMcJeon3y4 It’s worth keeping in mind that adding in fair doesn’t cause a big change (cut off in the figure, but there in the paper) ie adding another model doesn’t cause a big change in this case (of course, might be different in future applications)