Offsetting unabated agricultural emissions with CO2 removal to achieve ambitious climate targets.

The Representative Concentration Pathway 2.6 (RCP2.6), which is broadly compatible with the Paris Agreement's temperature goal by 1.5-2°C, contains substantial reductions in agricultural non-CO2 emissions besides the deployment of Carbon Dioxide Removal (CDR). Failing to mitigate agricultural m...

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Main Authors: Nicoletta Brazzola, Jan Wohland, Anthony Patt
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2021-01-01
Series:PLoS ONE
Online Access:https://doi.org/10.1371/journal.pone.0247887
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spelling doaj-78b7d125f5c54cbaa9b11531df314f5a2021-04-06T04:31:28ZengPublic Library of Science (PLoS)PLoS ONE1932-62032021-01-01163e024788710.1371/journal.pone.0247887Offsetting unabated agricultural emissions with CO2 removal to achieve ambitious climate targets.Nicoletta BrazzolaJan WohlandAnthony PattThe Representative Concentration Pathway 2.6 (RCP2.6), which is broadly compatible with the Paris Agreement's temperature goal by 1.5-2°C, contains substantial reductions in agricultural non-CO2 emissions besides the deployment of Carbon Dioxide Removal (CDR). Failing to mitigate agricultural methane and nitrous oxide emissions could contribute to an overshoot of the RCP2.6 warming by about 0.4°C. We explore using additional CDR to offset alternative agricultural non-CO2 emission pathways in which emissions either remain constant or rise. We assess the effects on the climate of calculating CDR rates to offset agricultural emission under two different approaches: relying on the 100-year global warming potential conversion metric (GWP100) and maintaining effective radiative forcing levels at exactly those of RCP2.6. Using a reduced-complexity climate model, we find that the conversion metric leads to a systematic underestimation of needed CDR, reaching only around 50% of the temperature mitigation needed to remain on the RCP2.6 track. This is mostly because the metric underestimates, in the near term, forcing from short-lived climate pollutants such as methane. We test whether alternative conversion metrics, the GWP20 and GWP*, are more suitable for offsetting purposes, and found that they both lead to an overestimation of the CDR requirements. Under alternative agricultural emissions pathways, holding to RCP2.6 total radiative forcing requires up to twice the amount of CDR that is already included in the RCP2.6. We examine the costs of this additional CDR, and the effects of internalizing these in several agricultural commodities. Assuming an average CDR cost by $150/tCO2, we find increases in prices of up to 41% for beef, 14% for rice, and 40% for milk in the United States relative to current retail prices. These figures are significantly higher (for beef and rice) under a global scenario, potentially threatening food security and welfare. Although the policy delivers a mechanism to finance the early deployment of CDR, using CDR to offset remaining high emissions may well hit other non-financial constraints and can thus only support, and not substitute, emission reductions.https://doi.org/10.1371/journal.pone.0247887
collection DOAJ
language English
format Article
sources DOAJ
author Nicoletta Brazzola
Jan Wohland
Anthony Patt
spellingShingle Nicoletta Brazzola
Jan Wohland
Anthony Patt
Offsetting unabated agricultural emissions with CO2 removal to achieve ambitious climate targets.
PLoS ONE
author_facet Nicoletta Brazzola
Jan Wohland
Anthony Patt
author_sort Nicoletta Brazzola
title Offsetting unabated agricultural emissions with CO2 removal to achieve ambitious climate targets.
title_short Offsetting unabated agricultural emissions with CO2 removal to achieve ambitious climate targets.
title_full Offsetting unabated agricultural emissions with CO2 removal to achieve ambitious climate targets.
title_fullStr Offsetting unabated agricultural emissions with CO2 removal to achieve ambitious climate targets.
title_full_unstemmed Offsetting unabated agricultural emissions with CO2 removal to achieve ambitious climate targets.
title_sort offsetting unabated agricultural emissions with co2 removal to achieve ambitious climate targets.
publisher Public Library of Science (PLoS)
series PLoS ONE
issn 1932-6203
publishDate 2021-01-01
description The Representative Concentration Pathway 2.6 (RCP2.6), which is broadly compatible with the Paris Agreement's temperature goal by 1.5-2°C, contains substantial reductions in agricultural non-CO2 emissions besides the deployment of Carbon Dioxide Removal (CDR). Failing to mitigate agricultural methane and nitrous oxide emissions could contribute to an overshoot of the RCP2.6 warming by about 0.4°C. We explore using additional CDR to offset alternative agricultural non-CO2 emission pathways in which emissions either remain constant or rise. We assess the effects on the climate of calculating CDR rates to offset agricultural emission under two different approaches: relying on the 100-year global warming potential conversion metric (GWP100) and maintaining effective radiative forcing levels at exactly those of RCP2.6. Using a reduced-complexity climate model, we find that the conversion metric leads to a systematic underestimation of needed CDR, reaching only around 50% of the temperature mitigation needed to remain on the RCP2.6 track. This is mostly because the metric underestimates, in the near term, forcing from short-lived climate pollutants such as methane. We test whether alternative conversion metrics, the GWP20 and GWP*, are more suitable for offsetting purposes, and found that they both lead to an overestimation of the CDR requirements. Under alternative agricultural emissions pathways, holding to RCP2.6 total radiative forcing requires up to twice the amount of CDR that is already included in the RCP2.6. We examine the costs of this additional CDR, and the effects of internalizing these in several agricultural commodities. Assuming an average CDR cost by $150/tCO2, we find increases in prices of up to 41% for beef, 14% for rice, and 40% for milk in the United States relative to current retail prices. These figures are significantly higher (for beef and rice) under a global scenario, potentially threatening food security and welfare. Although the policy delivers a mechanism to finance the early deployment of CDR, using CDR to offset remaining high emissions may well hit other non-financial constraints and can thus only support, and not substitute, emission reductions.
url https://doi.org/10.1371/journal.pone.0247887
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