Quantifying the terrestrial carbon feedback to anthropogenic carbon emission
Quantifying the terrestrial carbon feedback to anthropogenic carbon emission
The surface warming response to carbon emission is dependent on feedbacks operating in both the physical climate and carbon cycle systems, with physical climate feedbacks quantified via linearly combinable climate feedback terms, λclimate in Wm-2K-1. However, land carbon feedbacks are often quantified using a two-parameter description, with separate cumulative carbon uptake responses to surface warming, γL in PgC K-1, and rising atmospheric CO2concentration, βL in PgC ppm-1. Converting the γL and βL responses to an overall terrestrial carbon feedback parameter, λcarbon in Wm-2K-1, has remained problematic, with λcarbon affected by significant non-linear interactions between carbon-climate and carbon-concentration responses and a non-linear relation between atmospheric CO2and subsequent radiative forcing. This study presents new relationships quantifying how the overall steady state terrestrial carbon feedback to anthropogenic emission, λcarbon, is dependent on the terrestrial carbon responses to rising CO2and temperature, βL, and γL, and the physical climate feedback, λclimate. Non-linear interactions between βL and γL responses to carbon emission are quantified via a three-parameter description of the land carbon sensitivities to rising CO2 and temperature. Numerical vegetation model output supports the new relationships, revealing an emerging sensitivity of land carbon feedback to climate feedback of ∂λcarbon/∂λclimate~0.3. The results highlight that terrestrial carbon feedback and physical climate feedback cannot be considered in isolation: additional surface warming from stronger climate feedback is automatically compounded by reduced cooling from terrestrial carbon feedback, meanwhile around half the uncertainty in terrestrial carbon feedback originates from uncertainty in the physical climate feedback.
Goodwin, Philip
87dbb154-5c39-473a-8121-c794487ee1fd
Goodwin, Philip
87dbb154-5c39-473a-8121-c794487ee1fd
Goodwin, Philip
(2019)
Quantifying the terrestrial carbon feedback to anthropogenic carbon emission.
Earth's Future.
(doi:10.1029/2019EF001258).
Abstract
The surface warming response to carbon emission is dependent on feedbacks operating in both the physical climate and carbon cycle systems, with physical climate feedbacks quantified via linearly combinable climate feedback terms, λclimate in Wm-2K-1. However, land carbon feedbacks are often quantified using a two-parameter description, with separate cumulative carbon uptake responses to surface warming, γL in PgC K-1, and rising atmospheric CO2concentration, βL in PgC ppm-1. Converting the γL and βL responses to an overall terrestrial carbon feedback parameter, λcarbon in Wm-2K-1, has remained problematic, with λcarbon affected by significant non-linear interactions between carbon-climate and carbon-concentration responses and a non-linear relation between atmospheric CO2and subsequent radiative forcing. This study presents new relationships quantifying how the overall steady state terrestrial carbon feedback to anthropogenic emission, λcarbon, is dependent on the terrestrial carbon responses to rising CO2and temperature, βL, and γL, and the physical climate feedback, λclimate. Non-linear interactions between βL and γL responses to carbon emission are quantified via a three-parameter description of the land carbon sensitivities to rising CO2 and temperature. Numerical vegetation model output supports the new relationships, revealing an emerging sensitivity of land carbon feedback to climate feedback of ∂λcarbon/∂λclimate~0.3. The results highlight that terrestrial carbon feedback and physical climate feedback cannot be considered in isolation: additional surface warming from stronger climate feedback is automatically compounded by reduced cooling from terrestrial carbon feedback, meanwhile around half the uncertainty in terrestrial carbon feedback originates from uncertainty in the physical climate feedback.
Text
Goodwin-2019-Earth's_Future
- Accepted Manuscript
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Accepted/In Press date: 13 December 2019
e-pub ahead of print date: 14 December 2019
Identifiers
Local EPrints ID: 436681
URI: http://eprints.soton.ac.uk/id/eprint/436681
ISSN: 2328-4277
PURE UUID: b6d648b6-e596-46f8-99ee-6b4b02b87c9a
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Date deposited: 20 Dec 2019 18:29
Last modified: 17 Mar 2024 03:32
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