Thread by @Peters_Glen

The rise of Integrated Assessment Modelling (IAMs) in the climate science-policy interface since 1970.

Why have IAMs become more dominant over time?

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sciencedirect.com/science/articl…

"...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"

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

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PHASE 1: The emergence of global modelling:
* Limits to Growth
* Oil crises (MARKAL, EMF, IIASA, ...)
* Climate-economics (Nordhaus, ...)

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PHASE 2: Applications in policy:
* Acid rain: IIASA & RAINS - it seems a very proactive approach to help policy makers
* IAMs in climate: ASF, IMAGE
* IPCC ARs: SA90, IS92 scenarios used in assessment reports

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PHASE 3: Agendas to target setting
* Rapid expansion of IAMs & act as input into climate models: IPCC "provided an environment in which they could grow & be applied"
* Inspired to replicate the success of RAINS
* Target setting: Triptych approach, tolerable windows, 2°C, ...

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PHASE 4: IPCC WG3
* SRES, RCPs
* IAMs become the anchor for IPCC WG3 & connects WGs
* RCP2.6 (feasibility)
* IAM Model Intercomparisons
* Protocols, standardisation, databases, ...

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PHASE 5: Prominence (or dominance?)
* "IAMs ... the backbone of IPCC’s AR5"
* Paris Agreement (1.5°C, well below 2°C)
* Carbon budgets
* UNFCCC Structured Expert Dialogues
* UNEP Emissions Gap Report

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How could they do this?
* Enabling conditions
* 'Trust in numbers'
* Flexibility, breadth, & hybrid IAMs
* Pro-active community (anticipating & shaping demand)

[To me, it seems the IPCC was a rather important enabling factor, maybe also EU research funding]

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This is all rather impressive. Cut & paste this article for the next impact section of a research proposal! Guaranteed funding!

But, it is not without problems. Just a few points noted by the authors.

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"Paradoxically, the desire for numbers and predictions of policy communities certainly helps explain the influence of IAMs, yet is incongruent with the goals and conclusions of IAM analyses, which are explicitly non-predictive."

[IAMs are performative, if desired or not]

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"Considering the dense network of a relatively small group of authors & institutions underlying WGIII, this prominent position may be problematic as it risks 'narrowing' the construction of climate mitigation within the IPCC"

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"The IAM community formulated a number of criteria that scenario developers need to meet in order to be included in the scenario database ... thus strongly defined the scenario practice within the IPCC WGIII & excluded scenario approaches such as sectoral modelling."

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The IAM community has been very smart & active to get such a dominant position (whether intended or not), but with that comes a lot of power & therefore responsibility.

Very worth reading the paper to understand the evolution of IAMs... sciencedirect.com/science/articl…

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