Large Methane Emissions From the Pantanal During Rising Water‐Levels Revealed by Regularly Measured Lower Troposphere CH<sub>4</sub> Profiles

Gloor, M.; Gatti, Luciana V.; Wilson, Chris; Parker, Robert J.; Popa, M. E.; Chipperfield, Martyn P.; Poulter, Benjamin; Zhang, Z.; Basso, Luana S.; Miller, J. B.; McNorton, Joe; Jiménez, Carlos; Prigent, Catherine

doi:10.1029/2021gb006964

Cited by 11 publications

(12 citation statements)

References 77 publications

(111 reference statements)

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“…These values are consistent with the 2.0–2.8 Tg CH 4 y −1 reported by Gloor et al. (2021) based on direct emission measurements from vertical atmospheric profiles for 2 years. Upscaling from observations is challenging because of the high uncertainties in the tropical wetland area and in the length of the wet season.…”

Section: Upscalingsupporting

confidence: 93%

Assessing Methane Emissions From Tropical Wetlands: Uncertainties From Natural Variability and Drivers at the Global Scale

Murguia‐Flores,

Jaramillo,

Gallego‐Sala

2023

Global Biogeochemical Cycles

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Methane (CH4) emissions from tropical wetlands represent half of the global wetland emissions, but uncertainties remain concerning the extent of tropical methane sources. One limitation is to conceive tropical wetlands as a single ecosystem, especially in global land surface models. We estimate CH4 emissions and assess their environmental and anthropogenic drivers. We created a dataset with 101 studies involving 328‐point measurements, classified the sites into four wetland types, and included relevant biological and environmental information. We estimate the global CH4 emission rate from tropical wetlands as 35 (5‐160) mg CH4 m‐2 d‐1 (median, first and third quartile) and an annual global rate of 94 (56, 158) Tg y‐1. Fluxes differed among the wetland types, but except for anthropogenic factors, significant environmental drivers at the global scale could not be quantitatively identified due to high flux variability, even within wetland types. Coastal wetlands generate median emissions of 12(5‐23) Tg y‐1. Inland deep‐water wetlands emit 53 (32‐114) Tg y‐1, with highly variable areal extent. Emissions from inland shallow‐water wetlands are 52(33‐78) Tg y‐1 with variation due to seasonal changes in water table level. Human‐made wetlands emit 17 (10‐4) Tg y‐1. Pollution and N inputs from agriculture are significant anthropogenic drivers of emissions from tropical wetlands. Specific drivers of change need to be considered according to wetland type when estimating global emissions, as well as their specific vulnerability to global change. Additionally, these differences should be contemplated when implementing wetland management practices aimed at decreasing methane emissions.This article is protected by copyright. All rights reserved.

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Section: Upscalingsupporting

confidence: 93%

Assessing Methane Emissions From Tropical Wetlands: Uncertainties From Natural Variability and Drivers at the Global Scale

Murguia‐Flores,

Jaramillo,

Gallego‐Sala

2023

Global Biogeochemical Cycles

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“…These empirical constraints also suggest that the high early dry season emissions are not captured in the current model representations. 21 While the wet season often is the focus of tropical wetlands studies due to predicted high CH 4 emissions, our results indicate that dry season emissions in the Pantanal are largely underestimated in models. This suggests that work is needed to improve our mechanistic understanding of dry season emissions in tropical wetlands.…”

Section: ■ Results and Discussionmentioning

confidence: 68%

Underestimated Dry Season Methane Emissions from Wetlands in the Pantanal

Li,

Kort,

Bloom

et al. 2024

Environ. Sci. Technol.

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Tropical wetlands contribute ∼30% of the global methane (CH 4 ) budget. Limited observational constraints on tropical wetland CH 4 emissions lead to large uncertainties and disparities in representing emissions. In this work, we combine remote sensing observations with atmospheric and wetland models to investigate dry season wetland CH 4 emissions from the Pantanal region of South America. We incorporate inundation maps generated from the Cyclone Global Navigation Satellite System (CYGNSS) satellite constellation together with traditional inundation maps to generate an ensemble of wetland CH 4 emission realizations. We challenge these realizations with daily satellite observations for May−July when wetland CH 4 emission predictions diverge. We find that the CYGNSS inundation products predict larger emissions in May, in better agreement with observations. We use the model ensemble to generate an empirical observational constraint on CH 4 emissions independent of choice of inundation map, finding large dry season wetland CH 4 emissions (31.7 ± 13.6 and 32.0 ± 20.2 mg CH 4 /m 2 /day in May and June/July during 2018/2019, respectively). These May/ June/July emissions are 2−3 times higher than current models, suggesting that annual wetland emissions may be higher than traditionally simulated. Observed trends in the early dry season indicate that dynamics during this period are of importance in representing tropical wetland CH 4 behaviors.

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“…Annual emissions were estimated around 3.6 Tg/yr from the Llanos de Moxos wetlands. Further south, in the Pantanal wetlands of Brazil and Bolivia in the South American seasonal outer tropics, Gloor et al (2021) used a planetary boundary layer budgeting technique to estimate the Pantanal's total regional emissions of 2.0 to 2.8 Tg/yr, while their Bayesian inversion using an atmospheric transport model found even higher emissions of ∼3.3 Tg/yr.…”

Section: The Wetland Hypothesismentioning

confidence: 99%

Atmospheric methane: Comparison between methane’s record in 2006-2022 and during glacial terminations.

Nisbet

Manning

Dlugokencky

et al. 2023

Preprint

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Atmospheric methane’s rapid growth from 2006 to the present is unprecedented in the observational record. Isotopic evidence implies the growth is mainly driven by an increase in biogenically-sourced emissions, both from wetlands and ruminants, and waste. A significant part of methane’s current rise may come not from direct anthropogenic emissions and land use changes, but rather from a combination of natural biogenic feedback responses, occurring in response to the anthropogenic forcing. Although microbial emissions from agricultural and waste have increased between 2006-2020 by about 35 Tg/yr, perhaps 35-40 Tg/yr of the recent net growth in methane emissions may have been driven by natural biogenic processes, especially wetland feedbacks to climate change. Modelling comparison between the biogenic component of methane’s growth and isotopic shift in the 15 years from 2007-2022, and the global-scale climate reorganisations during the transitions from glacial to interglacial periods in the Pleistocene, shows that the modern growth event is comparable to or greater than the scale and speed of methane’s growth and isotopic shift during past glacial/interglacial termination events. It remains possible that current changes are related to decadal- or centennial-scale variability in precipitation and temperature and remain within the range of Holocene variability, or due to direct anthropogenic actions. But, though any current transition will differ greatly from the past glacial-interglacial changes, it is also possible methane’s remarkable growth and isotopic shift that began in 2006 may be a first indicator that a very large-scale reorganisation of the natural climate and biosphere system is under way.

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Large Methane Emissions From the Pantanal During Rising Water‐Levels Revealed by Regularly Measured Lower Troposphere CH₄ Profiles

Cited by 11 publications

References 77 publications

Assessing Methane Emissions From Tropical Wetlands: Uncertainties From Natural Variability and Drivers at the Global Scale

Assessing Methane Emissions From Tropical Wetlands: Uncertainties From Natural Variability and Drivers at the Global Scale

Underestimated Dry Season Methane Emissions from Wetlands in the Pantanal

Atmospheric methane: Comparison between methane’s record in 2006-2022 and during glacial terminations.

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Large Methane Emissions From the Pantanal During Rising Water‐Levels Revealed by Regularly Measured Lower Troposphere CH4 Profiles

Cited by 11 publications

References 77 publications

Assessing Methane Emissions From Tropical Wetlands: Uncertainties From Natural Variability and Drivers at the Global Scale

Assessing Methane Emissions From Tropical Wetlands: Uncertainties From Natural Variability and Drivers at the Global Scale

Underestimated Dry Season Methane Emissions from Wetlands in the Pantanal

Atmospheric methane: Comparison between methane’s record in 2006-2022 and during glacial terminations.

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Large Methane Emissions From the Pantanal During Rising Water‐Levels Revealed by Regularly Measured Lower Troposphere CH₄ Profiles