scholarly journals Role of regional wetland emissions in atmospheric methane variability

2016 ◽  
Vol 43 (21) ◽  
pp. 11,433-11,444 ◽  
Author(s):  
J. McNorton ◽  
E. Gloor ◽  
C. Wilson ◽  
G. D. Hayman ◽  
N. Gedney ◽  
...  
Keyword(s):  
Atmospheric Methane

scholarly journals The role of atomic chlorine in glacial-interglacial changes in the carbon-13 content of atmospheric methane

2011 ◽  
Vol 38 (4) ◽  
pp. n/a-n/a ◽  
Author(s):  
J. G. Levine ◽  
E. W. Wolff ◽  
A. E. Jones ◽  
L. C. Sime
Keyword(s):  
Atmospheric Methane ◽  
Atomic Chlorine

scholarly journals On the role of trend and variability in the hydroxyl radical (OH) in the global methane budget

2020 ◽  
Vol 20 (21) ◽  
pp. 13011-13022
Author(s):  
Yuanhong Zhao ◽  
Marielle Saunois ◽  
Philippe Bousquet ◽  
Xin Lin ◽  
Antoine Berchet ◽  
...  
Keyword(s):  
Hydroxyl Radical ◽  
El Niño ◽  
Climate Model ◽  
El Nino ◽  
Interannual Variations ◽  
Atmospheric Methane ◽  
Tropical Regions ◽  
Ch4 Emissions ◽  
Methane Budget

Abstract. Decadal trends and interannual variations in the hydroxyl radical (OH), while poorly constrained at present, are critical for understanding the observed evolution of atmospheric methane (CH4). Through analyzing the OH fields simulated by the model ensemble of the Chemistry–Climate Model Initiative (CCMI), we find (1) the negative OH anomalies during the El Niño years mainly corresponding to the enhanced carbon monoxide (CO) emissions from biomass burning and (2) a positive OH trend during 1980–2010 dominated by the elevated primary production and the reduced loss of OH due to decreasing CO after 2000. Both two-box model inversions and variational 4D inversions suggest that ignoring the negative anomaly of OH during the El Niño years leads to a large overestimation of the increase in global CH4 emissions by up to 10 ± 3 Tg yr−1 to match the observed CH4 increase over these years. Not accounting for the increasing OH trends given by the CCMI models leads to an underestimation of the CH4 emission increase by 23 ± 9 Tg yr−1 from 1986 to 2010. The variational-inversion-estimated CH4 emissions show that the tropical regions contribute most to the uncertainties related to OH. This study highlights the significant impact of climate and chemical feedbacks related to OH on the top-down estimates of the global CH4 budget.

Evidence for glacial geological controls on the hydrology of Maine (USA) peatlands

Geology ◽  
2020 ◽  
Vol 48 (8) ◽  
pp. 771-776
Author(s):  
Xi Chen ◽  
Xavier Comas ◽  
Andrew Reeve ◽  
Lee Slater
Keyword(s):  
Ground Penetrating Radar ◽  
Peat Soil ◽  
Spatial Association ◽  
Geochemical Data ◽  
Atmospheric Methane ◽  
Multiple Sources ◽  
Ch4 Production ◽  
Geological Factors ◽  
Ground Penetrating

Abstract Freshwater pools commonly form eccentric crescent patterns in peatlands, an important atmospheric methane (CH4) source, and show an apparent spatial association with eskers in some deglaciated regions. However, the role of underlying permeable glacial deposits such as eskers in regulating hydrogeology, and perhaps even carbon cycling, in peatlands is rarely considered. In this study, ground-penetrating radar imaging and direct coring confirmed that clustered pools coincide with buried esker crests in contact with peat soil in Caribou Bog and Kanokolus Bog in Maine (USA). Hydraulic head and geochemical data combined with lidar indicate vertical water flow from shallow peat toward the permeable esker crests, suggesting enhanced downward transport of labile organic carbon that presumably accelerates rates of methanogenesis in deep peat. Eskers might therefore serve as proxies for enhanced CH4 production in deep peat, as supported by differences in dissolved CH4 profiles depending on proximity to pools. Geographic data compiled from multiple sources suggest that many peatlands with eccentric pools appear to be located proximal to esker systems in Maine and Fennoscandia. These geological factors may be important, previously unrecognized controls on water and the carbon cycle in peatlands.

scholarly journals An analysis of atmospheric CH<sub>4</sub> concentrations from 1984 to 2008 with a single box atmospheric chemistry model

2012 ◽  
Vol 12 (11) ◽  
pp. 30259-30282 ◽  
Author(s):  
Z. Tan ◽  
Q. Zhuang
Keyword(s):  
Growth Rate ◽  
Atmospheric Chemistry ◽  
Methane Flux ◽  
Methane Emissions ◽  
Atmospheric Methane ◽  
Significant Drop ◽  
Oxidizing Power ◽  
The Mean

Abstract. We present a single box atmospheric chemistry model involving atmospheric methane (CH4), carbon monoxide (CO) and radical hydroxyl (OH) to analyze atmospheric CH4 concentrations from 1984 to 2008. When OH is allowed to vary, the modeled CH4 is 20 ppb higher than observations from the NOAA/ESRL and AGAGE networks for the end of 2008. However, when the OH concentration is held constant at 106 molecule cm−3, the simulated CH4 shows a trend approximately equal to observations. Both simulations show a clear slowdown in the CH4 growth rate during recent decades, from about 13 ppb yr−1 in 1984 to less than 5 ppb yr−1 in 2003. Furthermore, if the constant OH assumption is credible, we think that this slowdown is mainly due to a pause in the growth of wetland methane emissions. In simulations run for the Northern and Southern Hemispheres separately, we find that the Northern Hemisphere is more sensitive to wetland emissions, whereas the southern tends to be more perturbed by CH4 transportation, dramatic OH change, and biomass burning. When measured CO values from NOAA/ESRL are used to drive the model, changes in the CH4 growth rate become more consistent with observations, but the long-term increase in CH4 is underestimated. This shows that CO is a good indicator of short-term variations in oxidizing power in the atmosphere. The simulation results also indicate the significant drop in OH concentrations in 1998 (about 5% lower than the previous year) was probably due to an abrupt increase in wetland methane emissions during an intense EI Niño event. Using a fixed-lag Kalman smoother, we estimate the mean wetland methane flux is about 128 Tg yr−1 through the period 1984–2008. This study demonstrates the effectiveness in examining the role of OH and CO in affecting CH4.

scholarly journals Feasibility of Solar Updraft Towers as Photocatalytic Reactors for Removal of Atmospheric Methane–The Role of Catalysts and Rate Limiting Steps

2021 ◽  
Vol 9 ◽  
Author(s):  
Yanfang Huang ◽  
Yimin Shao ◽  
Yang Bai ◽  
Qingchun Yuan ◽  
Tingzhen Ming ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Removal Rate ◽  
Atmospheric Methane ◽  
Planetary Scale ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Gas Removal ◽  
Photocatalytic Reactors ◽  
Rate Limiting

Due to the alarming speed of global warming, greenhouse gas removal from atmosphere will be absolutely necessary in the coming decades. Methane is the second most harmful greenhouse gas in the atmosphere. There is an emerging technology proposed to incorporating photocatalysis with solar updraft Towers (SUT) to remove methane from the air at a planetary scale. In this study, we present a deep analysis by calculating the potential of methane removal in relation to the dimensions and configuration of SUT using different photocatalysts. The analysis shows that the methane removal rate increases with the SUT dimensions and can be enhanced by changing the configuration design. More importantly, the low methane removal rate on conventional TiO2 photocatalyst can be significantly improved to, for example, 42.5% on a more effective Ag-doped ZnO photocatalyst in a 200 MW SUT while the photocatalytic reaction is the rate limiting step. The factors that may further affect the removal of methane, such as more efficient photocatalysts, night operation and reaction zone are discussed as possible solutions to further improve the system.

scholarly journals Role of the Hudson Bay lowland as a source of atmospheric methane

1994 ◽  
Vol 99 (D1) ◽  
pp. 1439 ◽  
Author(s):  
Nigel T. Roulet ◽  
A. Jano ◽  
C. A. Kelly ◽  
L. F. Klinger ◽  
T. R. Moore ◽  
...  
Keyword(s):  
Hudson Bay ◽  
Atmospheric Methane ◽  
Hudson Bay Lowland

scholarly journals Climate versus emission drivers of methane lifetime from 1860–2100

2012 ◽  
Vol 12 (7) ◽  
pp. 18067-18105 ◽  
Author(s):  
J. G. John ◽  
A. M. Fiore ◽  
V. Naik ◽  
L. W. Horowitz ◽  
J. P. Dunne
Keyword(s):  
Climate Warming ◽  
Climate Model ◽  
Climate Forcing ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Atmospheric Methane ◽  
Future Evolution ◽  
The Individual ◽  
Future Work ◽  
Fully Coupled

Abstract. With a more-than-doubling in the atmospheric abundance of the potent greenhouse gas methane (CH4) since preindustrial times, and indications of renewed growth following a leveling off in recent years, questions arise as to future trends and resulting climate and public health impacts from continued growth without mitigation. Changes in atmospheric methane lifetime are determined by factors which regulate the abundance of OH, the primary methane removal mechanism, including changes in CH4 itself. We investigate the role of emissions of short-lived species and climate in determining the evolution of tropospheric methane lifetime in a suite of historical (1860–2005) and Representative Concentration Pathway (RCP) simulations (2006–2100), conducted with the Geophysical Fluid Dynamics Laboratory (GFDL) fully coupled chemistry-climate model (CM3). From preindustrial to present, CM3 simulates an overall 5% increase in CH4 lifetime due to a doubling of the methane burden which offsets coincident increases in nitrogen oxide (NOx) emissions. Over the last two decades, however, the methane lifetime declines steadily, coinciding with the most rapid climate warming and observed slow-down in CH4 growth rates, reflecting a possible negative feedback through the CH4 sink. The aerosol indirect effect plays a significant role in the CM3 climate and thus in the future evolution of the methane lifetime, due to the rapid projected decline of aerosols under all four RCPs. In all scenarios, the methane lifetime decreases (by 5–13%) except for the most extreme warming case (RCP8.5), where it increases by 4% due to the near-doubling of the CH4 abundance, reflecting a positive feedback on the climate system. In the RCP4.5 scenario changes in short-lived climate forcing agents reinforce climate warming and enhance OH, leading to a more-than-doubling of the decrease in methane lifetime from 2006 to 2100 relative to a simulation in which only well-mixed greenhouse gases are allowed to change along the RCP4.5 scenario (13% vs. 5%) Future work should include process-based studies to better understand and elucidate the individual mechanisms controlling methane lifetime.

Environmental factors affecting global atmospheric methane concentrations

1995 ◽  
Vol 19 (3) ◽  
pp. 322-335 ◽  
Author(s):  
Amy Tetlow Smith
Keyword(s):  
Temporal Distribution ◽  
Atmospheric Methane ◽  
Biological Origin ◽  
Factors Affecting ◽  
Biogenic Methane ◽  
Source Regions ◽  
Terrestrial Source ◽  
Micro Organisms ◽  
Process Based Models

Methane is a greenhouse gas of largely biological origin. Micro-organisms responsible for production of much of the atmospheric methane are directly affected by climate resulting in potential feedbacks between the atmosphere and the biosphere. Our current understanding of the role of methane in the climate system is reviewed in this article, with a brief discussion of biological, chemical, and physical processes responsible for the spatial and temporal distribution of atmos pheric methane. The magnitude of most methane sources is highly speculative, and their distributions are qualitatively understood. Most terrestrial source regions have been surveyed, but few have been studied in much detail. The strength of enteric sources is based on laboratory measurements of emissions from a few animals and estimates of global populations. Accuracy of the resulting flux size and distribution is highly suspect. Data available on either magnitude or distribution of non-biogenic methane sources are scarce. Models of the influence of climate on biological methane sources are primarily regressions dependent on measures of heat and water in the environment. Process-based models derived from biological and physical principles are called for in order to address environmental conditions unlike the present.

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