Changing climatic controls on the greenhouse gas balance of thermokarst bogs during succession after permafrost thaw.
Permafrost thaw in northern peatlands causes collapse of permafrost peat plateaus and thermokarst bog development, with potential impacts on atmospheric greenhouse gas exchange. Here, we measured methane and carbon dioxide fluxes over 3 years (including winters) using static chambers along two perma...
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ftpubmed:38967139 2024-09-15T18:29:12+00:00 Changing climatic controls on the greenhouse gas balance of thermokarst bogs during succession after permafrost thaw. Heffernan, Liam Estop-Aragonés, Cristian Kuhn, McKenzie A Holger-Knorr, Klaus Olefeldt, David 2024 Jul https://doi.org/10.1111/gcb.17388 https://pubmed.ncbi.nlm.nih.gov/38967139 eng eng Wiley https://doi.org/10.1111/gcb.17388 https://pubmed.ncbi.nlm.nih.gov/38967139 © 2024 The Author(s). Global Change Biology published by John Wiley & Sons Ltd. Glob Chang Biol ISSN:1365-2486 Volume:30 Issue:7 carbon dioxide greenhouse gas balance methane net ecosystem exchange peatland permafrost radiative forcing thermokarst Journal Article 2024 ftpubmed https://doi.org/10.1111/gcb.17388 2024-07-05T16:01:00Z Permafrost thaw in northern peatlands causes collapse of permafrost peat plateaus and thermokarst bog development, with potential impacts on atmospheric greenhouse gas exchange. Here, we measured methane and carbon dioxide fluxes over 3 years (including winters) using static chambers along two permafrost thaw transects in northwestern Canada, spanning young (~30 years since thaw), intermediate and mature thermokarst bogs (~200 years since thaw). Young bogs were wetter, warmer and had more hydrophilic vegetation than mature bogs. Methane emissions increased with wetness and soil temperature (40 cm depth) and modelled annual estimates were greatest in the young bog during the warmest year and lowest in the mature bog during the coolest year (21 and 7 g C-CH4 m-2 year-1, respectively). The dominant control on net ecosystem exchange (NEE) in the mature bog (between +20 and -54 g C-CO2 m-2 year-1) was soil temperature (5 cm), causing net CO2 loss due to higher ecosystem respiration (ER) in warmer years. In contrast, wetness controlled NEE in the young and intermediate bogs (between +55 and -95 g C-CO2 m-2 year-1), where years with periodic inundation at the beginning of the growing season caused greater reduction in gross primary productivity than in ER leading to CO2 loss. Winter fluxes (November-April) represented 16% of annual ER and 38% of annual CH4 emissions. Our study found NEE of thermokarst bogs to be close to neutral and rules out large CO2 losses under current conditions. However, high CH4 emissions after thaw caused a positive net radiative forcing effect. While wet conditions favouring high CH4 emissions only persist for the initial young bog period, we showed that continued climate warming with increased ER, and thus, CO2 losses from the mature bog can cause net positive radiative forcing which would last for centuries after permafrost thaw. Article in Journal/Newspaper Peat permafrost Thermokarst PubMed Central (PMC) Global Change Biology 30 7 |
institution |
Open Polar |
collection |
PubMed Central (PMC) |
op_collection_id |
ftpubmed |
language |
English |
topic |
carbon dioxide greenhouse gas balance methane net ecosystem exchange peatland permafrost radiative forcing thermokarst |
spellingShingle |
carbon dioxide greenhouse gas balance methane net ecosystem exchange peatland permafrost radiative forcing thermokarst Heffernan, Liam Estop-Aragonés, Cristian Kuhn, McKenzie A Holger-Knorr, Klaus Olefeldt, David Changing climatic controls on the greenhouse gas balance of thermokarst bogs during succession after permafrost thaw. |
topic_facet |
carbon dioxide greenhouse gas balance methane net ecosystem exchange peatland permafrost radiative forcing thermokarst |
description |
Permafrost thaw in northern peatlands causes collapse of permafrost peat plateaus and thermokarst bog development, with potential impacts on atmospheric greenhouse gas exchange. Here, we measured methane and carbon dioxide fluxes over 3 years (including winters) using static chambers along two permafrost thaw transects in northwestern Canada, spanning young (~30 years since thaw), intermediate and mature thermokarst bogs (~200 years since thaw). Young bogs were wetter, warmer and had more hydrophilic vegetation than mature bogs. Methane emissions increased with wetness and soil temperature (40 cm depth) and modelled annual estimates were greatest in the young bog during the warmest year and lowest in the mature bog during the coolest year (21 and 7 g C-CH4 m-2 year-1, respectively). The dominant control on net ecosystem exchange (NEE) in the mature bog (between +20 and -54 g C-CO2 m-2 year-1) was soil temperature (5 cm), causing net CO2 loss due to higher ecosystem respiration (ER) in warmer years. In contrast, wetness controlled NEE in the young and intermediate bogs (between +55 and -95 g C-CO2 m-2 year-1), where years with periodic inundation at the beginning of the growing season caused greater reduction in gross primary productivity than in ER leading to CO2 loss. Winter fluxes (November-April) represented 16% of annual ER and 38% of annual CH4 emissions. Our study found NEE of thermokarst bogs to be close to neutral and rules out large CO2 losses under current conditions. However, high CH4 emissions after thaw caused a positive net radiative forcing effect. While wet conditions favouring high CH4 emissions only persist for the initial young bog period, we showed that continued climate warming with increased ER, and thus, CO2 losses from the mature bog can cause net positive radiative forcing which would last for centuries after permafrost thaw. |
format |
Article in Journal/Newspaper |
author |
Heffernan, Liam Estop-Aragonés, Cristian Kuhn, McKenzie A Holger-Knorr, Klaus Olefeldt, David |
author_facet |
Heffernan, Liam Estop-Aragonés, Cristian Kuhn, McKenzie A Holger-Knorr, Klaus Olefeldt, David |
author_sort |
Heffernan, Liam |
title |
Changing climatic controls on the greenhouse gas balance of thermokarst bogs during succession after permafrost thaw. |
title_short |
Changing climatic controls on the greenhouse gas balance of thermokarst bogs during succession after permafrost thaw. |
title_full |
Changing climatic controls on the greenhouse gas balance of thermokarst bogs during succession after permafrost thaw. |
title_fullStr |
Changing climatic controls on the greenhouse gas balance of thermokarst bogs during succession after permafrost thaw. |
title_full_unstemmed |
Changing climatic controls on the greenhouse gas balance of thermokarst bogs during succession after permafrost thaw. |
title_sort |
changing climatic controls on the greenhouse gas balance of thermokarst bogs during succession after permafrost thaw. |
publisher |
Wiley |
publishDate |
2024 |
url |
https://doi.org/10.1111/gcb.17388 https://pubmed.ncbi.nlm.nih.gov/38967139 |
genre |
Peat permafrost Thermokarst |
genre_facet |
Peat permafrost Thermokarst |
op_source |
Glob Chang Biol ISSN:1365-2486 Volume:30 Issue:7 |
op_relation |
https://doi.org/10.1111/gcb.17388 https://pubmed.ncbi.nlm.nih.gov/38967139 |
op_rights |
© 2024 The Author(s). Global Change Biology published by John Wiley & Sons Ltd. |
op_doi |
https://doi.org/10.1111/gcb.17388 |
container_title |
Global Change Biology |
container_volume |
30 |
container_issue |
7 |
_version_ |
1810470604443222016 |