for changes in soil carbon under Kyoto: Long-term data-sets need to be improved to reduce uncertainty associated with model projections

P. D. Falloon, Peter Smith

Research output: Contribution to journalArticle

Abstract

Soils can be used as a biospheric sink for carbon under Article 3.4 of the Kyoto Protocol and parties are able to use agricultural soil carbon sinks to contribute towards carbon emission reduction targets. This should be done 'taking into account uncertainties, transparency in reporting, and verifiability'. Models are often tested against data sets of long-term changes in soil organic carbon (SOC), but most data sets have only mean SOC values available at each sample date, with no estimates of error about the mean. We show that when using data sets that do not include estimates of error about the mean, it is not possible to reduce the error (root mean squared error) between modelled and measured values below 6.8-8.5%, even with site-specific model calibration. Equivalent errors for model runs using regional default input values are 12-34%. Using error as an indicator of the certainty that can be attached to model projections, we show that a significant reduction in uncertainty is needed for Kyoto accounting. Uncertainties for modelling during the first Kyoto Commitment Period could be reduced by better replication of soil measurements at benchmark sites. This would allow model error to be separated from measurement error, which would allow more comprehensive model testing and, ultimately, more certainty to be attached to model predictions.

Original languageEnglish
Pages (from-to)265-269
Number of pages4
JournalSoil Use & Management
Volume19
DOIs
Publication statusPublished - 2003

Keywords

  • Kyoto accounting
  • uncertainty
  • modelling
  • soil carbon
  • carbon sequestration
  • Europe
  • ORGANIC-MATTER
  • SIMULATING TRENDS
  • REGIONAL-SCALE
  • EUROSOMNET
  • EUROPE

Cite this

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title = "for changes in soil carbon under Kyoto: Long-term data-sets need to be improved to reduce uncertainty associated with model projections",
abstract = "Soils can be used as a biospheric sink for carbon under Article 3.4 of the Kyoto Protocol and parties are able to use agricultural soil carbon sinks to contribute towards carbon emission reduction targets. This should be done 'taking into account uncertainties, transparency in reporting, and verifiability'. Models are often tested against data sets of long-term changes in soil organic carbon (SOC), but most data sets have only mean SOC values available at each sample date, with no estimates of error about the mean. We show that when using data sets that do not include estimates of error about the mean, it is not possible to reduce the error (root mean squared error) between modelled and measured values below 6.8-8.5{\%}, even with site-specific model calibration. Equivalent errors for model runs using regional default input values are 12-34{\%}. Using error as an indicator of the certainty that can be attached to model projections, we show that a significant reduction in uncertainty is needed for Kyoto accounting. Uncertainties for modelling during the first Kyoto Commitment Period could be reduced by better replication of soil measurements at benchmark sites. This would allow model error to be separated from measurement error, which would allow more comprehensive model testing and, ultimately, more certainty to be attached to model predictions.",
keywords = "Kyoto accounting, uncertainty, modelling, soil carbon, carbon sequestration, Europe, ORGANIC-MATTER, SIMULATING TRENDS, REGIONAL-SCALE, EUROSOMNET, EUROPE",
author = "Falloon, {P. D.} and Peter Smith",
year = "2003",
doi = "10.1111/j.1475-2743.2003.tb00313.x",
language = "English",
volume = "19",
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journal = "Soil Use & Management",
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T1 - for changes in soil carbon under Kyoto: Long-term data-sets need to be improved to reduce uncertainty associated with model projections

AU - Falloon, P. D.

AU - Smith, Peter

PY - 2003

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N2 - Soils can be used as a biospheric sink for carbon under Article 3.4 of the Kyoto Protocol and parties are able to use agricultural soil carbon sinks to contribute towards carbon emission reduction targets. This should be done 'taking into account uncertainties, transparency in reporting, and verifiability'. Models are often tested against data sets of long-term changes in soil organic carbon (SOC), but most data sets have only mean SOC values available at each sample date, with no estimates of error about the mean. We show that when using data sets that do not include estimates of error about the mean, it is not possible to reduce the error (root mean squared error) between modelled and measured values below 6.8-8.5%, even with site-specific model calibration. Equivalent errors for model runs using regional default input values are 12-34%. Using error as an indicator of the certainty that can be attached to model projections, we show that a significant reduction in uncertainty is needed for Kyoto accounting. Uncertainties for modelling during the first Kyoto Commitment Period could be reduced by better replication of soil measurements at benchmark sites. This would allow model error to be separated from measurement error, which would allow more comprehensive model testing and, ultimately, more certainty to be attached to model predictions.

AB - Soils can be used as a biospheric sink for carbon under Article 3.4 of the Kyoto Protocol and parties are able to use agricultural soil carbon sinks to contribute towards carbon emission reduction targets. This should be done 'taking into account uncertainties, transparency in reporting, and verifiability'. Models are often tested against data sets of long-term changes in soil organic carbon (SOC), but most data sets have only mean SOC values available at each sample date, with no estimates of error about the mean. We show that when using data sets that do not include estimates of error about the mean, it is not possible to reduce the error (root mean squared error) between modelled and measured values below 6.8-8.5%, even with site-specific model calibration. Equivalent errors for model runs using regional default input values are 12-34%. Using error as an indicator of the certainty that can be attached to model projections, we show that a significant reduction in uncertainty is needed for Kyoto accounting. Uncertainties for modelling during the first Kyoto Commitment Period could be reduced by better replication of soil measurements at benchmark sites. This would allow model error to be separated from measurement error, which would allow more comprehensive model testing and, ultimately, more certainty to be attached to model predictions.

KW - Kyoto accounting

KW - uncertainty

KW - modelling

KW - soil carbon

KW - carbon sequestration

KW - Europe

KW - ORGANIC-MATTER

KW - SIMULATING TRENDS

KW - REGIONAL-SCALE

KW - EUROSOMNET

KW - EUROPE

U2 - 10.1111/j.1475-2743.2003.tb00313.x

DO - 10.1111/j.1475-2743.2003.tb00313.x

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JO - Soil Use & Management

JF - Soil Use & Management

SN - 0266-0032

ER -