Modeling spatiotemporal dynamics of global wetlands: comprehensive evaluation of a new sub-grid TOPMODEL parameterization and uncertainties

Zhang, Zhen; Zimmermann, Niklaus E.; Kaplan, Jed O.; Poulter, Benjamin

doi:10.5194/bg-13-1387-2016

Cited by 74 publications

(62 citation statements)

References 101 publications

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“…We also analyze CH 4 emission and surface inundation extent from two process-based wetland models: LPJ-wsl1534 and CLM4.53536. Additionally, we derive an independent estimate of inundation extent from remotely sensed Surface WAter Microwave Product Series (SWAMPs37).…”

Section: Methods and Datamentioning

confidence: 99%

Enhanced methane emissions from tropical wetlands during the 2011 La Niña

Pandey

Houweling

Krol

et al. 2017

Sci Rep

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Year-to-year variations in the atmospheric methane (CH4) growth rate show significant correlation with climatic drivers. The second half of 2010 and the first half of 2011 experienced the strongest La Niña since the early 1980s, when global surface networks started monitoring atmospheric CH4 mole fractions. We use these surface measurements, retrievals of column-averaged CH4 mole fractions from GOSAT, new wetland inundation estimates, and atmospheric δ13C-CH4 measurements to estimate the impact of this strong La Niña on the global atmospheric CH4 budget. By performing atmospheric inversions, we find evidence of an increase in tropical CH4 emissions of ∼6–9 TgCH4 yr−1 during this event. Stable isotope data suggest that biogenic sources are the cause of this emission increase. We find a simultaneous expansion of wetland area, driven by the excess precipitation over the Tropical continents during the La Niña. Two process-based wetland models predict increases in wetland area consistent with observationally-constrained values, but substantially smaller per-area CH4 emissions, highlighting the need for improvements in such models. Overall, tropical wetland emissions during the strong La Niña were at least by 5% larger than the long-term mean.

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Section: Methods and Datamentioning

confidence: 99%

Enhanced methane emissions from tropical wetlands during the 2011 La Niña

Pandey

Houweling

Krol

et al. 2017

Sci Rep

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“…HydroSHEDS was shown to agree most closely with observed wetland area in a comparison with existing global elevation datasets and parameterization schemes (18). Our TOPMODEL approach was optimized by calibrating parameters to match observations from a hybrid wetland area dataset (26) and a regional remote sensing surface inundation dataset (27).…”

Section: Methodsmentioning

confidence: 99%

“…Depending on scenarios, wetland CH 4 feedbacks translate to an increase in additional global mean radiative forcing of 0.04 W·m −2 to 0.19 W·m −2 by the end of the 21st century. Under the "worst-case" RCP8.5 scenario, with no climate mitigation, boreal CH 4 emissions are enhanced by 18.05 Tg to 41.69 Tg, due to thawing of inundated areas during the cold season (December to May) and rising temperature, while tropical CH 4 emissions accelerate with a total increment of 48.36 Tg to 87.37 Tg by 2099. Our results suggest that climate mitigation policies must consider mitigation of wetland CH 4 feedbacks to maintain average global warming below 2°C.…”

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confidence: 99%

“…sustained pulse−response model (17). A state-of-the-art land surface model, Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJ-DGVM) Wald Schnee und Landscaft version (LPJ-wsl), was used to quantify terrestrial wetland CH 4 emissions, in which permafrost and wetland area distribution and dynamics were estimated prognostically (18). Simulated global CH 4 emissions, calibrated such as to minimize the discrepancy between contemporary global annual CH 4 emissions, were estimated as a function of substrate, soil temperature, and soil moisture (19).…”

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confidence: 99%

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Emerging role of wetland methane emissions in driving 21st century climate change

Zhang

Zimmermann

Stenke

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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192

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Wetland methane (CH 4 ) emissions are the largest natural source in the global CH 4 budget, contributing to roughly one third of total natural and anthropogenic emissions. As the second most important anthropogenic greenhouse gas in the atmosphere after CO 2 , CH 4 is strongly associated with climate feedbacks. However, due to the paucity of data, wetland CH 4 feedbacks were not fully assessed in the Intergovernmental Panel on Climate Change Fifth Assessment Report. The degree to which future expansion of wetlands and CH 4 emissions will evolve and consequently drive climate feedbacks is thus a question of major concern. Here we present an ensemble estimate of wetland CH 4 emissions driven by 38 general circulation models for the 21st century. We find that climate changeinduced increases in boreal wetland extent and temperature-driven increases in tropical CH 4 T errestrial wetlands are among the largest biogenic sources of methane contributing to growing atmospheric CH 4 concentrations (1) and are, in turn, highly sensitive to climate change (2). However, radiative feedbacks from wetland CH 4 emissions were not considered in the Coupled Model Intercomparison Project Phase 5 (CMIP5), and Integrated Assessment Models (IAM) assumed anthropogenic sources to be the only driver responsible for the increase of atmospheric CH 4 burden since the 1750s (3). The role of wetland CH 4 emissions, however, may play an increasingly larger role in future atmospheric growth of methane because of the large stocks of mineral and organic carbon stored under anaerobic conditions in both boreal and tropical regions. Paleoclimatological and contemporary observations of the climate sensitivity of wetland methane emissions suggest the potential for a large feedback (4), but there remains large uncertainty in quantifying the actual range of the response (5, 6).Increasing air temperature is linked to the thawing of permafrost and to increased rates of soil microbial activity (7), which directly lead to greater CH 4 production in soils due to thaw-induced change in surface wetland areas (8). In the tropics, wetland areal extent is also influenced by precipitation, which affects the area of surface inundation, water table depth, and soil moisture that, in turn, promote methanogenesis. Elevated CO 2 concentrations can increase ecosystem water use efficiency and thus soil moisture, and also increase soil carbon substrate availability for microbial activities (9). Tropical wetlands, for which a decline in inundation was observed in recent decades (10), are already exposed to increasing frequencies in extreme climate events, e.g., heat waves, floods, and droughts, and changes in rainfall distribution (11) and variability in methane emissions (12). Meanwhile, northern highlatitude ecosystems are experiencing a more rapid temperature increase than elsewhere globally and with increased rates of soil respiration (13), yet, locally at least, no response in methane emissions (14). Despite the importance of these feedbacks noted by the Intergovernmen...

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“…Last but not least, popular methods for defining the extent of wetlands include using "Prescribed constant wetland extents" (as was done here) and the "Hydrological model" [90,91]. The latter method uses a model to simulate the dynamical wetland extent.…”

Section: Uncertainties and Future Needsmentioning

confidence: 99%

Modeling CH4 Emissions from Natural Wetlands on the Tibetan Plateau over the Past 60 Years: Influence of Climate Change and Wetland Loss

Zhang

Zou

et al. 2016

Atmosphere

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Abstract:The natural wetlands of the Tibetan Plateau (TP) are considered to be an important natural source of methane (CH 4 ) to the atmosphere. The long-term variation in CH 4 associated with climate change and wetland loss is still largely unknown. From 1950 to 2010, CH 4 emissions over the TP were analyzed using a model framework that integrates CH4MOD wetland , TOPMODEL, and TEM models. Our simulation revealed a total increase of 15% in CH 4 fluxes, from 6.1 g m´2 year´1 to 7.0 g m´2 year´1. This change was primarily induced by increases in temperature and precipitation. Although climate change has accelerated CH 4 fluxes, the total amount of regional CH 4 emissions decreased by approximately 20% (0.06 Tg-i.e., from 0.28 Tg in the 1950s to 0.22 Tg in the 2000s), due to the loss of 1.41 million ha of wetland. Spatially, both CH 4 fluxes and regional CH 4 emissions showed a decreasing trend from the southeast to the northwest of the study area. Lower CH 4 emissions occurred in the northwestern Plateau, while the highest emissions occurred in the eastern edge. Overall, our results highlighted the fact that wetland loss decreased the CH 4 emissions by approximately 20%, even though climate change has accelerated the overall CH 4 emission rates over the last six decades.

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Modeling spatiotemporal dynamics of global wetlands: comprehensive evaluation of a new sub-grid TOPMODEL parameterization and uncertainties

Cited by 74 publications

References 101 publications

Enhanced methane emissions from tropical wetlands during the 2011 La Niña

Enhanced methane emissions from tropical wetlands during the 2011 La Niña

Emerging role of wetland methane emissions in driving 21st century climate change

Modeling CH4 Emissions from Natural Wetlands on the Tibetan Plateau over the Past 60 Years: Influence of Climate Change and Wetland Loss

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