Strategic Ensemble Design (closed)

Task team period of service: 7th December 2022 – 2nd December 2024

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Co-leads: Ben Sanderson, CICERO and Isla Simpson, NCAR

This task team focused on on ensemble design and interpretation to aid scoping of the next phase of the Coupled Model Intercomparison Project (CMIP7).

Robust assessments of mitigation policy effectiveness, and of adaptation strategy in the face of climate change require a climate modelling strategy which represents a balance of state of art process understanding, tractability and utility on a policy timescale.

Challenge

Successive generations of CMIP have seen the project grow in scope – with increasing process-specific subprojects to better address specific scientific questions, while the political and societal landscape surrounding the wider topic of climate change have developed dramatically in the aftermath of the Paris Agreement. Meanwhile, questions remain on how to best sample and calibrate models in order to produce simulations which are relevant for assessment.

Aim & Objectives

The aim of this Task Team was to consider how future best strategy for CMIP should address those evolving societal demands which can be met only by process-resolving computational Earth System Modelling. It considered how to better represent both detailed climate impact and mitigation processes, given expectations of computational (and human) capacity over the timescale of CMIP7.

Early objectives were:

Review existing CMIP6 core and satellite protocols. Identify critical linkages and evident knowledge gaps.
Consider how ad-hoc model calibration and sampling strategies in CMIP could be improved to better inform projected impacts in multi-model distributions of future climate change.
Review model development axes which could improve utility and added value of future CMIP-class models for climate assessment (emissions driven capacity, calibration frameworks, process representation, resolution, timescale of simulations), and assess urgency and scope for addressing issues in coming CMIP cycles.
Consider revision of DECK protocol to provide better calibration targets (and tests) for simple climate model architectures and scenarios representing key policy-relevant climate system uncertainties in achieving the goals of the Paris agreement.
Coordinate a workshop to showcase perspectives and multi-model analysis needs for CMIP7.

Decisions and publications

The Task Team played a pivotal role in the initial selection and development of the AR7 Fast Track experiments (see experiment viewer here), working both within the team itself and with the wider community. The AR7 Fast Track experiment selection was endorsed by the Working Group on Coupled Modelling (WGCM) and Earth System Modelling and Observations (ESMO) core project in March 2024. The SED TT further supported the development of DECK guidance to accommodate the emissions driven focus of CMIP7, and initiated further discussions on spin up metrics, potential for sub-sampling and the representation of Bio Energy Carbon Capture and Storage (BECCS). Many of these topics will continue under different activities or working groups and have contributed to “An evolving Coupled Model Intercomparison Project phase 7 (CMIP7) and Fast Track in support of future climate assessment” (Dunne et al., 2024, submitted to GMD).

Members (closed)