Climate tipping-point potential and paradoxical production of methane in a changing ocean

Dang, Hongyue; Li, Jia

doi:10.1007/s11430-017-9265-y

Cited by 4 publications

(5 citation statements)

References 220 publications

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“…Our data across the subtropical North Atlantic Ocean unambiguously indicates an oversaturation in CH4 of the surface layer (400 m) of 110 to 370%, which is in agreement with previous observations describing concentrations varying between 2-5 nmol/l with maximum of 10 nmol/l (Scranton and Brewer, 1977;Conrad and Seiler, 1988;Forster et al, 2009;de la Paz et al, 2015;Leonte et al , 2020). This is also in line with previous observations that describe the upper oceanic layer as a source of CH4 to the atmosphere (Reeburgh, 2007b;Dang and Li, 2018), in subtropical areas of the global ocean and also in some regions of the Arctic Ocean (Kitidis et al, 2010;Kudo et al, 2018). To date, only the Southern Ocean is undersaturated in CH4, although this can be due to the scarcity of data collected, which needs to be complemented (Bui et al, 2018).…”

Section: Methane Distribution In Surface Waters Of the Subtropical No...supporting

confidence: 89%

“…The accumulation of organic matter and nutrients in these areas provide favourable conditions for both aerobic and anaerobic CH4 production. It is expected that with increasing stratification and subsequent reduction in nutrient supply to the surface oligotrophic North Atlantic Ocean, the prevailing P-limitation will be further exacerbated, whereas coastal and shelf regions with increasing anthropogenic inputs of nutrients, could experience more frequent cyanobacterial blooms which, will in turn enhance CH4 production (Dang and Li, 2018).…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Among them, methane (CH4) is considered the second largest contributor to Earth warming, after carbon dioxide (CO2), with an atmospheric concentration of 1,866 ppb (IPCC, 2021). Over the last 50 years, CH4 concentrations have increased by 20 % (Karl et al, 2008), (Rhee et al, 2009 and is expected to rise further, by approximately 2 % per year (Dang and Li, 2018).Oceans are generally thought of as a minor contributor to the total global CH4 budget, however, recent calculations indicate that oceans could emit 6 to 17 Tg CH4/yr, i.e. 1 to 10 % of the total natural emissions (Weber et al, 2019).…”

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confidence: 99%

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An update on dissolved methane distribution in the subtropical North Atlantic Ocean

et al. 2022

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Abstract. Methane (CH4) is a potent greenhouse gas and plays a significant role in recent increasing global temperatures. The oceans are a natural source of methane contributing to atmospheric methane concentrations, yet our understanding of the oceanic methane cycle is poorly constrained. Accumulating evidence indicates that a significant part of oceanic CH4 is produced in oxygenated surface waters as a by-product of phytoplanktonic activity. This study focused on the subtropical North Atlantic Ocean (26∘ N, 80′ W and 26∘ N, 18′ W) where the distribution of dissolved CH4 concentrations and associated air–sea fluxes during winter 2020 were investigated. Water samples from 64 stations were collected from the upper water column up to depths of 400 m. The upper oxic mixed layer was oversaturated in dissolved CH4 with concentrations ranging 3–7 nmol L−1, with the highest concentrations of 7–10 nmol L−1 found to the east of the transect, consistent with other subtropical regions of the world's oceans. The high anomalies of dissolved CH4 were found to be associated with phosphate-depleted waters and regions where the abundance of the ubiquitous picocyanobacteria Synechococcus and Prochlorococcus were elevated. Although other phytoplanktonic phyla cannot be excluded, this suggests that cyanobacteria contribute to the release of CH4 in this region. The calculation of air–sea fluxes further confirmed the subtropical North Atlantic Ocean as a source of CH4. This study provides evidence to corroborate the key role that picocyanobacteria play in helping to explain the oversaturation of CH4 found in surface mixed layer of the open ocean, otherwise known as the “ocean methane paradox”.

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Section: Methane Distribution In Surface Waters Of the Subtropical No...supporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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An update on dissolved methane distribution in the subtropical North Atlantic Ocean

et al. 2022

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“…Conserving and restoring VCEs for maintaining and enhancing blue carbon sequestration have been proposed as an integral part of strategies for climate remediation (Geraldi et al, 2019). However, the VCEs are also hotspots of non-CO 2 greenhouse gas emissions due to anthropogenic eutrophication-enhanced microbial activities including CH 4 and N 2 O production (Angell et al, 2018;Dang and Li, 2018). Although VCEs may contribute to climate change mitigation at the local and national scales, they occupy a very limited spatial extent on Earth and thus their climate remediation potential is small at the global scale (Taillardat et al, 2018).…”

Section: Coastal Vs Oceanic Blue Carbon Sinksmentioning

confidence: 99%