When is a trend meaningful? Insights to carbon cycle variability from an initial-condition large ensemble

Abstract Internal climate variability (ICV) creates a range of climate trajectories, which are superimposed upon the forced response. A single climate model realization may not represent forced change alone and may diverge from other realizations, as well as observations, due to ICV. We use an initi...

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Main Authors: Gordon B. Bonan, Clara Deser, William R. Wieder, Danica L. Lombardozzi, Flavio Lehner
Format: Article
Language:English
Published: Nature Portfolio 2024-12-01
Series:npj Climate and Atmospheric Science
Online Access:https://doi.org/10.1038/s41612-024-00878-w
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author Gordon B. Bonan
Clara Deser
William R. Wieder
Danica L. Lombardozzi
Flavio Lehner
author_facet Gordon B. Bonan
Clara Deser
William R. Wieder
Danica L. Lombardozzi
Flavio Lehner
author_sort Gordon B. Bonan
collection DOAJ
description Abstract Internal climate variability (ICV) creates a range of climate trajectories, which are superimposed upon the forced response. A single climate model realization may not represent forced change alone and may diverge from other realizations, as well as observations, due to ICV. We use an initial-condition large ensemble of simulations with the Community Earth System Model (CESM2) to show that ICV produces a range of outcomes in the terrestrial carbon cycle. Trends in gross primary production (GPP) from 1991 to 2020 differ among ensemble members due to the different climate trajectories resulting from ICV. We quantify how ICV imparts on GPP trends and apply our methodology to the observational record. Observed changes in GPP at two long-running eddy covariance flux towers are consistent with ICV, challenging the understanding of forced changes in the carbon cycle at these locations. A probabilistic framework that accounts for ICV is needed to interpret carbon cycle trends.
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spelling doaj-art-ef3d62ec1fb3499d87ae2b5ee1aaec432025-08-20T02:31:46ZengNature Portfolionpj Climate and Atmospheric Science2397-37222024-12-017111110.1038/s41612-024-00878-wWhen is a trend meaningful? Insights to carbon cycle variability from an initial-condition large ensembleGordon B. Bonan0Clara Deser1William R. Wieder2Danica L. Lombardozzi3Flavio Lehner4Climate and Global Dynamics Laboratory, NSF National Center for Atmospheric ResearchClimate and Global Dynamics Laboratory, NSF National Center for Atmospheric ResearchClimate and Global Dynamics Laboratory, NSF National Center for Atmospheric ResearchClimate and Global Dynamics Laboratory, NSF National Center for Atmospheric ResearchClimate and Global Dynamics Laboratory, NSF National Center for Atmospheric ResearchAbstract Internal climate variability (ICV) creates a range of climate trajectories, which are superimposed upon the forced response. A single climate model realization may not represent forced change alone and may diverge from other realizations, as well as observations, due to ICV. We use an initial-condition large ensemble of simulations with the Community Earth System Model (CESM2) to show that ICV produces a range of outcomes in the terrestrial carbon cycle. Trends in gross primary production (GPP) from 1991 to 2020 differ among ensemble members due to the different climate trajectories resulting from ICV. We quantify how ICV imparts on GPP trends and apply our methodology to the observational record. Observed changes in GPP at two long-running eddy covariance flux towers are consistent with ICV, challenging the understanding of forced changes in the carbon cycle at these locations. A probabilistic framework that accounts for ICV is needed to interpret carbon cycle trends.https://doi.org/10.1038/s41612-024-00878-w
spellingShingle Gordon B. Bonan
Clara Deser
William R. Wieder
Danica L. Lombardozzi
Flavio Lehner
When is a trend meaningful? Insights to carbon cycle variability from an initial-condition large ensemble
npj Climate and Atmospheric Science
title When is a trend meaningful? Insights to carbon cycle variability from an initial-condition large ensemble
title_full When is a trend meaningful? Insights to carbon cycle variability from an initial-condition large ensemble
title_fullStr When is a trend meaningful? Insights to carbon cycle variability from an initial-condition large ensemble
title_full_unstemmed When is a trend meaningful? Insights to carbon cycle variability from an initial-condition large ensemble
title_short When is a trend meaningful? Insights to carbon cycle variability from an initial-condition large ensemble
title_sort when is a trend meaningful insights to carbon cycle variability from an initial condition large ensemble
url https://doi.org/10.1038/s41612-024-00878-w
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