Reduced Complexity Model Intercomparison Project Phase 2: Synthesizing Earth System Knowledge for Probabilistic Climate Projections

Journal Article · Fri Jun 04 00:00:00 EDT 2021 · Earth's Future

DOI:https://doi.org/10.1029/2020EF001900· OSTI ID:1786272

Nicholls, Z. ^[1]; Meinshausen, M. ^[2]; Lewis, J. ^[3]; Corradi, M. Rojas ^[4]; Dorheim, K. ^[5]; Gasser, T. ^[6]; Gieseke, R. ^[7]; Hope, A. P. ^[8]; Leach, N. J. ^[9]; McBride, L. A. ^[10]; Quilcaille, Y. ^[6]; Rogelj, J. ^[11]; Salawitch, R. J. ^[12]; Samset, B. H. ^[13]; Sandstad, M. ^[13]; Shiklomanov, A. ^[14]; Skeie, R. B. ^[13]; Smith, C. J. ^[15]; Smith, S. J. ^[16]; Su, X. ^[17] ; Tsutsui, J. ^[18]; Vega‐Westhoff, B. ^[19]; Woodard, D. L. ^[20]

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1. Australian‐German Climate &, Energy College University of Melbourne Parkville VIC Australia, School of Earth Sciences University of Melbourne Parkville VIC Australia
2. Australian‐German Climate &, Energy College University of Melbourne Parkville VIC Australia, School of Earth Sciences University of Melbourne Parkville VIC Australia, Potsdam Institute for Climate Impact Research Member of the Leibniz Association Potsdam Germany
3. Australian‐German Climate &, Energy College University of Melbourne Parkville VIC Australia
4. Department of Geophysics University of Chile Santiago Chile, Center for Climate and Resilience Research CR2 Santiago Chile
5. Pacficic Northwest National Laboratory Richland WA USA
6. International Institute for Applied Systems Analysis Laxenburg Austria
7. Independent Researcher Potsdam Germany
8. Department of Atmospheric and Oceanic Science University of Maryland‐College Park College Park USA
9. Department of Physics Atmospheric, Oceanic, and Planetary Physics University of Oxford Oxford UK
10. Department of Chemistry and Biochemistry University of Maryland‐College Park College Park MD USA
11. International Institute for Applied Systems Analysis Laxenburg Austria, Grantham Institute Imperial College London London UK
12. Department of Atmospheric and Oceanic Science University of Maryland‐College Park College Park USA, Department of Chemistry and Biochemistry University of Maryland‐College Park College Park MD USA, Earth System Science Interdisciplinary Center University of Maryland‐College Park College Park MD USA
13. CICERO Center for International Climate Research Oslo Norway
14. NASA Goddard Space Flight Center Greenbelt MD USA
15. International Institute for Applied Systems Analysis Laxenburg Austria, Priestley International Centre for Climate University of Leeds Leeds UK
16. Joint Global Change Research Institute Pacific Northwest National Laboratory College Park MD USA
17. Research Institute for Global Change/Research Center for Environmental Modeling and Application/Earth System Model Development and Application Group Japan Agency for Marine‐Earth Science and Technology Yokohama Japan
18. Environmental Science Research Laboratory Central Research Institute of Electric Power Industry Abiko Japan
19. Department of Atmospheric Sciences University of Illinois at Urbana‐Champaign Urbana IL USA
20. Center for Climate and Resilience Research CR2 Santiago Chile

Abstract

Over the last decades, climate science has evolved rapidly across multiple expert domains. Our best tools to capture state‐of‐the‐art knowledge in an internally self‐consistent modeling framework are the increasingly complex fully coupled Earth System Models (ESMs). However, computational limitations and the structural rigidity of ESMs mean that the full range of uncertainties across multiple domains are difficult to capture with ESMs alone. The tools of choice are instead more computationally efficient reduced complexity models (RCMs), which are structurally flexible and can span the response dynamics across a range of domain‐specific models and ESM experiments. Here we present Phase 2 of the Reduced Complexity Model Intercomparison Project (RCMIP Phase 2), the first comprehensive intercomparison of RCMs that are probabilistically calibrated with key benchmark ranges from specialized research communities. Unsurprisingly, but crucially, we find that models which have been constrained to reflect the key benchmarks better reflect the key benchmarks. Under the low‐emissions SSP1‐1.9 scenario, across the RCMs, median peak warming projections range from 1.3 to 1.7°C (relative to 1850–1900, using an observationally based historical warming estimate of 0.8°C between 1850–1900 and 1995–2014). Further developing methodologies to constrain these projection uncertainties seems paramount given the international community's goal to contain warming to below 1.5°C above preindustrial in the long‐term. Our findings suggest that users of RCMs should carefully evaluate their RCM, specifically its skill against key benchmarks and consider the need to include projections benchmarks either from ESM results or other assessments to reduce divergence in future projections.

• Sponsoring Organization: USDOE
• OSTI ID: 1786272
• Alternate ID(s): OSTI ID: 1819058; OSTI ID: 1786274
• Journal Information: Earth's Future, Journal Name: Earth's Future Journal Issue: 6 Vol. 9; ISSN 2328-4277
• Publisher: American Geophysical Union (AGU)
• Country of Publication: United States
• Language: English