Evaluation of Integrated Assessment Model Hindcast Experiments: a Case Study of the GCAM 3.0 Land Use Module

TitleEvaluation of Integrated Assessment Model Hindcast Experiments: a Case Study of the GCAM 3.0 Land Use Module
Publication TypeJournal Article
Year of Publication2017
AuthorsSnyder, Abigail C., Link Robert P., and Calvin Katherine V.
JournalGeoscientific Model Development
Volume10
Pages4307-4319
Date Published11/2017
Abstract / Summary

Hindcasting experiments (conducting a model forecast for a time period in which observational data is available) are being undertaken increasingly often by the Integrated Assessment Model (IAM) community, across many scales of models. When they are undertaken, the results are often evaluated using global aggregates or otherwise highly aggregated skill scores that mask deficiencies. We select a set of deviation based measures that can be applied at different spatial scales (regional versus global) to make 5 evaluating the large number of variable-region combinations in IAMs more tractable. We also identify performance benchmarks for these measures, based on the statistics of the observational dataset, that allow a model to be evaluated in absolute terms rather than relative to the performance of other models at similar tasks. An ideal evaluation method for hindcast experiments in IAMs would feature both absolute measures for evaluation of a single experiment for a single model and relative measures to compare the results of multiple experiments for a single model or the same experiment repeated 10 across multiple models, such as in community intercomparison studies. The performance benchmarks highlight the use of this scheme for model evaluation in absolute terms, providing information about the reasons a model may perform poorly on a given measure and therefore identifying opportunities for improvement. To demonstrate the use of and types of results possible with the evaluation method, the measures are applied to the results of a past hindcast experiment focusing on land allocation in the Global Change Assessment Model (GCAM) version 3.0. The question of how to more holistically evaluate models as 15 complex as IAMs is an area for future research. We find quantitative evidence that global aggregates alone are not sufficient for evaluating IAMs that require global supply to equal global demand at each time period, such as GCAM. The results of this work indicate it is unlikely that a single evaluation measure for all variables in an IAM exists, and therefore sector by sector evaluation may be necessary. 

URLhttps://www.geosci-model-dev.net/10/4307/2017/
DOI10.5194/gmd-10-4307-2017
Funding Program: 
Journal: Geoscientific Model Development
Year of Publication: 2017
Volume: 10
Pages: 4307-4319
Date Published: 11/2017

Hindcasting experiments (conducting a model forecast for a time period in which observational data is available) are being undertaken increasingly often by the Integrated Assessment Model (IAM) community, across many scales of models. When they are undertaken, the results are often evaluated using global aggregates or otherwise highly aggregated skill scores that mask deficiencies. We select a set of deviation based measures that can be applied at different spatial scales (regional versus global) to make 5 evaluating the large number of variable-region combinations in IAMs more tractable. We also identify performance benchmarks for these measures, based on the statistics of the observational dataset, that allow a model to be evaluated in absolute terms rather than relative to the performance of other models at similar tasks. An ideal evaluation method for hindcast experiments in IAMs would feature both absolute measures for evaluation of a single experiment for a single model and relative measures to compare the results of multiple experiments for a single model or the same experiment repeated 10 across multiple models, such as in community intercomparison studies. The performance benchmarks highlight the use of this scheme for model evaluation in absolute terms, providing information about the reasons a model may perform poorly on a given measure and therefore identifying opportunities for improvement. To demonstrate the use of and types of results possible with the evaluation method, the measures are applied to the results of a past hindcast experiment focusing on land allocation in the Global Change Assessment Model (GCAM) version 3.0. The question of how to more holistically evaluate models as 15 complex as IAMs is an area for future research. We find quantitative evidence that global aggregates alone are not sufficient for evaluating IAMs that require global supply to equal global demand at each time period, such as GCAM. The results of this work indicate it is unlikely that a single evaluation measure for all variables in an IAM exists, and therefore sector by sector evaluation may be necessary. 

DOI: 10.5194/gmd-10-4307-2017
Citation:
Snyder, AC, RP Link, and KV Calvin.  2017.  "Evaluation of Integrated Assessment Model Hindcast Experiments: a Case Study of the GCAM 3.0 Land Use Module."  Geoscientific Model Development 10: 4307-4319.  https://doi.org/10.5194/gmd-10-4307-2017.