Evaluating climate emulation: fundamental  impulse testing of simple climate models

Schwarber, Adria; Smith, Steve; Hartin, Corinne; Vega-Westhoff, Benjamin Aaron; Sriver, R. L.

doi:10.5194/esd-10-729-2019

Cited by 22 publications

(22 citation statements)

References 53 publications

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“…This might reduce estimates of BC temperature impact in future assessments; however, large differences between model responses remain. We also note that the temperature response to a change in BC emissions in the MAGICC6 model used here (Schwarber et al 2018) is different in character to the response shown in a step emission experiments in two coupled climate model experiments (Sand et al 2015;Yang et al 2019), further emphasizing the uncertainty in climate responses to BC emissions in particular. Overall, therefore, results for the impact of black carbon on surface temperature should be considered indicative.…”

Section: Discussionmentioning

confidence: 79%

“…Critically, MAGICC6 includes a multi-region representation of forcing and climate responses. This results in a more rapid response of the climate system to aerosol forcings, located predominately over land and in the northern hemisphere such as sulfate and black carbon (Schwarber et al 2018), as also seen in earth system models (Shindell 2014). The use of a common climate model eliminates spurious differences due to different climate model versions and parameter assumptions used by individual modeling groups.…”

Section: Methodsmentioning

confidence: 99%

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Impact of methane and black carbon mitigation on forcing and temperature: a multi-model scenario analysis

et al. 2020

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The relatively short atmospheric lifetimes of methane (CH4) and black carbon (BC) have focused attention on the potential for reducing anthropogenic climate change by reducing Short-Lived Climate Forcer (SLCF) emissions. This paper examines radiative forcing and global mean temperature results from the Energy Modeling Forum (EMF)-30 multi-model suite of scenarios addressing CH4 and BC mitigation, the two major short-lived climate forcers. Central estimates of temperature reductions in 2040 from an idealized scenario focused on reductions in methane and black carbon emissions ranged from 0.18–0.26 °C across the nine participating models. Reductions in methane emissions drive 60% or more of these temperature reductions by 2040, although the methane impact also depends on auxiliary reductions that depend on the economic structure of the model. Climate model parameter uncertainty has a large impact on results, with SLCF reductions resulting in as much as 0.3–0.7 °C by 2040. We find that the substantial overlap between a SLCF-focused policy and a stringent and comprehensive climate policy that reduces greenhouse gas emissions means that additional SLCF emission reductions result in, at most, a small additional benefit of ~ 0.1 °C in the 2030–2040 time frame.

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Section: Discussionmentioning

confidence: 79%

Section: Methodsmentioning

confidence: 99%

Impact of methane and black carbon mitigation on forcing and temperature: a multi-model scenario analysis

et al. 2020

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“…In this study we used Hector v 2.3.0 as the parent model, providing both of HIRM's primary and only inputs. We selected Hector because it is open source, well documented, fast-executing, and has a structure that makes it easy to obtain "clean" IRFs from model runs (Schwarber et al, 2019). As noted above, however, HIRM can be coupled with any parent model that can provide its inputs.…”

Section: Parent Model Descriptionmentioning

confidence: 99%

“…Comprehensive process-based SCMs such as Hector and MAGICC have thousands of lines of code and take significant effort to expand. On the other extreme, simple impulse response models can be expressed in a few equations and are readily implemented, but these simplifications can produce biases in results (van Vuuren et al, 2011;Schwarber et al, 2019). We discuss here a framework that can be used as a test bed for SCM development and analysis.…”

Section: Introductionmentioning

confidence: 99%

HIRM v1.0: a hybrid impulse response model for climate modeling and uncertainty analyses

2021

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Abstract. Simple climate models (SCMs) are frequently used in research and decision-making communities because of their flexibility, tractability, and low computational cost. SCMs can be idealized, flexibly representing major climate dynamics as impulse response functions, or process-based, using explicit equations to model possibly nonlinear climate and Earth system dynamics. Each of these approaches has strengths and limitations. Here we present and test a hybrid impulse response modeling framework (HIRM) that combines the strengths of process-based SCMs in an idealized impulse response model, with HIRM's input derived from the output of a process-based model. This structure enables the model to capture some of the major nonlinear dynamics that occur in complex climate models as greenhouse gas emissions transform to atmospheric concentration to radiative forcing to climate change. As a test, the HIRM framework was configured to emulate the total temperature of the simple climate model Hector 2.0 under the four Representative Concentration Pathways and the temperature response of an abrupt 4 times CO2 concentration step. HIRM was able to reproduce near-term and long-term Hector global temperature with a high degree of fidelity. Additionally, we conducted two case studies to demonstrate potential applications for this hybrid model: examining the effect of aerosol forcing uncertainty on global temperature and incorporating more process-based representations of black carbon into a SCM. The open-source HIRM framework has a range of applications including complex climate model emulation, uncertainty analyses of radiative forcing, attribution studies, and climate model development.

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“…The IPCC special report has further provided comprehensive evidence on the impacts at global warming of 1.5 • C and the impacts avoided compared to higher levels (Ove Hoegh-Guldberg et al, 2018). Particularly, substantially lower impacts are expected for extreme weather events (Seneviratne et al, 2018), water availability, regionally specific drought or flooding risks (Döll et al, 2018;Karnauskas et al, 2018;Hasson et al, 2019), crop production in particular in tropical regions (Faye et al, 2018;Schleussner et al, 2018b), circulation changes including extreme El Niño, persistence of weather patterns and tropical rainy season changes (Pfleiderer et al, 2019;Saeed et al, 2018;Wang et al, 2017), land and marine ecosystems (Warren et al, 2018;Schleussner et al, 2016a;Cheung et al, 2016), cryosphere changes including glacier and sea-ice loss (Laura and Dirk, 2018;Kraaijenbrink et al, 2017), (extreme) sea-level rise in particular beyond 2100 (Mengel et al, 2018;Schleussner et al, 2018a;Rasmussen et al, 2018), and economic damages (Burke et al, 2018;Pretis et al, 2018) and a wide range of other sectoral impacts (Arnell et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Incremental improvements of 2030 targets insufficient to achieve the Paris Agreement goals

et al. 2020

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Abstract. Current global mitigation ambition up to 2030 under the Paris Agreement, reflected in the National Determined Contributions (NDCs), is insufficient to achieve the agreement's 1.5 ∘C long-term temperature limit. As governments are preparing new and updated NDCs for 2020, the question as to how much collective improvement is achieved is a pivotal one for the credibility of the international climate regime. The recent Special Report on Global Warming of 1.5 ∘C by the Intergovernmental Panel on Climate Change has assessed a wide range of scenarios that achieve the 1.5 ∘C limit. Those pathways are characterised by a substantial increase in near-term action and total greenhouse gas (GHG) emission levels about 50 % lower than what is implied by current NDCs. Here we assess the outcomes of different scenarios of NDC updating that fall short of achieving this 1.5 ∘C benchmark. We find that incremental improvements in reduction targets, even if achieved globally, are insufficient to align collective ambition with the goals of the Paris Agreement. We provide estimates for global mean temperature increase by 2100 for different incremental NDC update scenarios and illustrate climate impacts under those median scenarios for extreme temperature, long-term sea-level rise and economic damages for the most vulnerable countries. Under the assumption of maintaining ambition as reflected in current NDCs up to 2100 and beyond, we project a reduction in the gross domestic product (GDP) in tropical countries of around 60 % compared to a no-climate-change scenario and median long-term sea-level rise of close to 2 m in 2300. About half of these impacts can be avoided by limiting warming to 1.5 ∘C or below. Scenarios of more incremental NDC improvements do not lead to comparable reductions in climate impacts. An increase in aggregated NDC ambition of big emitters by 33 % in 2030 does not reduce presented climate impacts by more than about half compared to limiting warming to 1.5 ∘C. Our results underscore that a transformational increase in 2030 ambition is required to achieve the goals of the Paris Agreement and avoid the worst impacts of climate change.

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Evaluating climate emulation: fundamental impulse testing of simple climate models

Cited by 22 publications

References 53 publications

Impact of methane and black carbon mitigation on forcing and temperature: a multi-model scenario analysis

Impact of methane and black carbon mitigation on forcing and temperature: a multi-model scenario analysis

HIRM v1.0: a hybrid impulse response model for climate modeling and uncertainty analyses

Incremental improvements of 2030 targets insufficient to achieve the Paris Agreement goals

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