We don't need another decade building more complex models that exploit exascale computing, but one that:
1. Better understands & characterizes fundamental conceptual issues
2. Integrates multi-disciplinary knowledge & perspectives

1/

nature.com/articles/s4146…
Many presume that inadequacies of current models can be solved with more resolution, more detail, more computer.

But, fundamental questions on the inadequacies of models have note been addressed (eg model structure, initial conditions, nonlinear dynamics, etc)

2/
"Climate economists [have] spent decades attempting to provide ever-better numerical estimates of a benefit-cost ratio... Even if the ECS isn’t strictly fat-tailed, the benefit-cost ratio [is] highly sensitive to ... parameters which suffer from deep uncertainty"

3/
"Before ploughing billions into developing specialised computers & associated computer models, it would be wise to first develop a good theoretical understanding of what is necessary & sufficient to build models capable of such high-resolution predictions"

4/
The article focuses mainly on climate modeling (eg regional impacts) & cost-benefit IAMs, but the points raised apply much more broadly.

Generally speaking, modelers (all too often) like generating & interpreting numbers, not understanding if those numbers are robust.

5/5

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More from @Peters_Glen

27 Nov
En tråd på noen høydepunkter i et intervju med @THEenerWE @HildeNyman på "Det gir ingen mening å se på «worst case scenario»"

1/

enerwe.no/cicero-energip…
Myndigheter bygger på eksisterende politikk, så de trenger å vite hvor vi går med denne politikken, ikke hvor vi hadde gått uten politikk.

2/
Vi trenger mye mer kunnskap om hvilken innvirkning på klima vi kan forvente, ikke mer kunnskap om hvor ille det blir hvis ikke vi gjør noe.

3/
Read 9 tweets
26 Nov
The rise of Integrated Assessment Modelling (IAMs) in the climate science-policy interface since 1970.

Why have IAMs become more dominant over time?

1/

sciencedirect.com/science/articl… Image
"...although IAMs aim to function as ‘heuristic guides’ to explore strategies, they are in fact performative: they shape the possibility space in which future options for climate action are discussed & thus the content of policy deliberation in international climate politics"

2/
The authors find five phases representing shifts in the position of IAMs in the climate science-policy interface.

3/ Image
Read 14 tweets
20 Nov
THREAD: Does the @IEA 1.5°C scenario (Net-Zero Emissions 2050) need carbon dioxide removal?

See my presentation at #WEOWeek or read this thread...

Video:
Slides: www2.slideshare.net/GlenPeters_CIC…
2. Background: Most scenarios have positive emissions (brown) & carbon dioxide removal (green) to get a net (black).

Because of hard-to-mitigate sectors, CDR is needed to:
1. Offset residual emissions
2. Bring temperatures down (optional)

cicero.oslo.no/no/posts/klima…
3. (bonus extra). It is not necessary to have so much CDR that it causes temperature overshoot (light green in previous figure) because of net-negative emissions.

Here is a scenario which just goes to net-zero, & has enough CDR to stay there.
Read 11 tweets
18 Nov
Where does the European (EU27+UK) land sink come from?

It is mainly forest land remaining forest land. This is essentially managed forests, but also includes update from environmental factors (eg warmer climate & CO₂ fertilisation).

1/ Image
There are large variations across countries. Ireland has a large source from grasslands (not sure of the background, but I am guessing drained peat lands essentially?).

2/ Image
The Nordics all have large forest sinks, and their sinks are large relative to domestic emissions. Sweden, for example, is nearly has net-zero CO₂ emissions if the land sink is included.

3/ ImageImageImage
Read 6 tweets
17 Nov
@benmsanderson I guess it depends who the user is.

If it is just an academic exercise, then assuming this & that, to find what happens to coal is fine. This will also vary by model, given assumptions.

SSP2-45 from 6 models, very different answers... Academically interesting.

1/
@benmsanderson If I am a user, what do I do with that spread? Same socioeconomics, same effective climate policy, completely different outcomes (SSP is sort of current trends continue). Coal could rise or decline... Which may be true, but one would want to dig deeper...

2/
@benmsanderson Of course, every other year the path looking forward may differ depending on events, so need to redo scenarios again (& again)... But, that is just the way it is.

You can do scenarios which include current policies, I have not plotted those here.

3/
Read 4 tweets
17 Nov
Where will coal go in the next decade?

Baseline scenarios without climate policy can still have declining coal, if the socioeconomics (colours) are favourable (SSP1, SSP2, etc): low population, preference for clean air, etc.

Unlikely coal will grow SSP3 or SSP5 style...

1/
Under weak mitigation (colours are radiative forcing levels in 2100, bold are marker scenarios), coal can either decrease or increase...

But, given what we know today, what is the narrative that would have increasing or decreasing coal?

2/
Given the current pressure on coal, I would expect coal to be flat & then declining slowly (in the current policy environment), faster if policies are ramped up (like China, US, etc, net-zero).

Which scenarios should I use to get a realistic picture of coal?

3/
Read 6 tweets

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