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Detection of fossil fuel emission trends in the presence of natural carbon cycle variability

Yin, Yi and Bowman, Kevin and Bloom, A. Anthony and Worden, John (2019) Detection of fossil fuel emission trends in the presence of natural carbon cycle variability. Environmental Research Letters, 14 (8). Art. No. 084050. ISSN 1748-9326. doi:10.1088/1748-9326/ab2dd7.

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Atmospheric CO₂ observations have the potential to monitor regional fossil fuel emission (FFCO₂) changes to support carbon mitigation efforts such as the Paris Accord, but they must contend with the confounding impacts of the natural carbon cycle. Here, we quantify trend detection time and magnitude in gridded total CO₂ fluxes—the sum of FFCO₂ and natural carbon fluxes—under an idealized assumption that monthly total CO₂ fluxes can be perfectly resolved at a 2°×2° resolution. Using Coupled Model Intercomparison Project 5 (CMIP5) 'business-as-usual' emission scenarios to represent FFCO₂ and simulated net biome exchange (NBE) to represent natural carbon fluxes, we find that trend detection time for the total CO₂ fluxes at such a resolution has a median of 10 years across the globe, with significant spatial variability depending on FFCO₂ magnitude and NBE variability. Differences between trends in the total CO₂ fluxes and the underlying FFCO₂ component highlight the role of natural carbon cycle variability in modulating regional detection of FFCO₂ emission trends using CO₂ observations alone, particularly in the tropics and subtropics where mega-cities with large populations are developing rapidly. Using CO₂ estimates alone at such a spatiotemporal resolution can only quantify fossil fuel trends in a few places—mostly limited to arid regions. For instance, in the Middle East, FFCO₂ can explain more than 75% of the total CO₂ trends in ~70% of the grids, but only ~20% of grids in China can meet such criteria. Only a third of the 25 megacities we analyze here show total CO₂ trends that are primarily explained (>75%) by FFCO₂. Our analysis provides a theoretical baseline at a global scale for the design of regional FFCO₂ monitoring networks and underscores the importance of estimating biospheric interannual variability to improve the accuracy of FFCO₂ trend monitoring. We envision that this can be achieved with a fully integrated carbon cycle assimilation system with explicit constraints on FFCO₂ and NBE, respectively.

Item Type:Article
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URLURL TypeDescription
Yin, Yi0000-0003-4750-4997
Bowman, Kevin0000-0002-8659-1117
Bloom, A. Anthony0000-0002-1486-1499
Worden, John0000-0003-0257-9549
Additional Information:© 2019 The Author(s). Published by IOP Publishing Ltd. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 12 March 2019; Accepted 28 June 2019; Accepted Manuscript online 28 June 2019; Published 14 August 2019. The authors are very grateful to the CMIP5 project and ESG Federation for making ESM simulations publicly available. The research was supported by the NASA CMS-Flux project NNH16ZDA001N-CMS and a NASA Postdoctoral Program fellowship award to Y Yin. The research was carried out, in part, at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
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NASA Postdoctoral ProgramUNSPECIFIED
Issue or Number:8
Record Number:CaltechAUTHORS:20191216-150529172
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Official Citation:Yi Yin et al 2019 Environ. Res. Lett. 14 084050
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100313
Deposited By: Tony Diaz
Deposited On:16 Dec 2019 23:12
Last Modified:12 Jul 2022 19:52

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