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Identification and characterization of abrupt changes in the land uptake of carbon

Identification and characterization of abrupt changes in the land uptake of carbon
Identification and characterization of abrupt changes in the land uptake of carbon
A recent study of the net land carbon sink estimated using the Mauna Loa, Hawaii atmospheric CO2record, fossil fuel estimates, and a suite of ocean models suggests that the mean of the net land carbon uptake remained approximately constant for three decades and increased after 1988/1989. Due to the large variability in the net land uptake, it is not possible to determine the exact timing and nature of the increase robustly by visual inspection. Here, we develop a general methodology to objectively determine the nature and timing of the shift in the net land uptake based on the Schwarz Information Criterion. We confirm that it is likely that an abrupt shift in the mean net land carbon uptake occurred in 1988. After taking into account the variability in the net land uptake due to the influence of volcanic aerosols and the El Niño Southern Oscillation, we find that it is most likely that there is a remaining step increase at the same time (p-values of 0.01 and 0.04 for Mauna Loa and South Pole, respectively) of about 1 Pg C/yr. Thus, we conclude that neither the effect of volcanic eruptions nor the El Niño Southern Oscillation are the causes of the sudden increase of the land carbon sink. By also applying our methodology to the atmospheric growth rate of CO2, we demonstrate that it is likely that the atmospheric growth rate of CO2 exhibits a step decrease between two fitted lines in 1988–1989, which is most likely due to the shift in the net land uptake of carbon.
abrupt shift, atmospheric co2 growth rate, carbon sinks, change point detection, net land uptake
0886-6236
GB1007-[14pp]
Beaulieu, Claudie
13ae2c11-ebfe-48d9-bda9-122cd013c021
Sarmiento, Jorge L.
45f5964b-15e6-43e8-bdd4-8789e2eb87cb
Mikaloff Fletcher, Sara E.
27a97f12-0481-41cd-9f10-472f0afa7b72
Chen, Jie
7181526d-ec25-480e-a35e-37bf4616e131
Medvigy, David
9059193e-83e8-4727-9e57-eebe0ed4bfd8
Beaulieu, Claudie
13ae2c11-ebfe-48d9-bda9-122cd013c021
Sarmiento, Jorge L.
45f5964b-15e6-43e8-bdd4-8789e2eb87cb
Mikaloff Fletcher, Sara E.
27a97f12-0481-41cd-9f10-472f0afa7b72
Chen, Jie
7181526d-ec25-480e-a35e-37bf4616e131
Medvigy, David
9059193e-83e8-4727-9e57-eebe0ed4bfd8

Beaulieu, Claudie, Sarmiento, Jorge L., Mikaloff Fletcher, Sara E., Chen, Jie and Medvigy, David (2012) Identification and characterization of abrupt changes in the land uptake of carbon. Global Biogeochemical Cycles, 26 (1), GB1007-[14pp]. (doi:10.1029/2010GB004024).

Record type: Article

Abstract

A recent study of the net land carbon sink estimated using the Mauna Loa, Hawaii atmospheric CO2record, fossil fuel estimates, and a suite of ocean models suggests that the mean of the net land carbon uptake remained approximately constant for three decades and increased after 1988/1989. Due to the large variability in the net land uptake, it is not possible to determine the exact timing and nature of the increase robustly by visual inspection. Here, we develop a general methodology to objectively determine the nature and timing of the shift in the net land uptake based on the Schwarz Information Criterion. We confirm that it is likely that an abrupt shift in the mean net land carbon uptake occurred in 1988. After taking into account the variability in the net land uptake due to the influence of volcanic aerosols and the El Niño Southern Oscillation, we find that it is most likely that there is a remaining step increase at the same time (p-values of 0.01 and 0.04 for Mauna Loa and South Pole, respectively) of about 1 Pg C/yr. Thus, we conclude that neither the effect of volcanic eruptions nor the El Niño Southern Oscillation are the causes of the sudden increase of the land carbon sink. By also applying our methodology to the atmospheric growth rate of CO2, we demonstrate that it is likely that the atmospheric growth rate of CO2 exhibits a step decrease between two fitted lines in 1988–1989, which is most likely due to the shift in the net land uptake of carbon.

Full text not available from this repository.

More information

e-pub ahead of print date: 19 January 2012
Published date: March 2012
Keywords: abrupt shift, atmospheric co2 growth rate, carbon sinks, change point detection, net land uptake
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 352252
URI: https://eprints.soton.ac.uk/id/eprint/352252
ISSN: 0886-6236
PURE UUID: 57a3a311-5953-4ffa-813a-209f79608fbd

Catalogue record

Date deposited: 08 May 2013 10:07
Last modified: 10 Sep 2019 16:30

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