Methane bubbling from northern lakes: present and future contributions to the global methane budget

Walter, K. M.; Smith, L. C.; Chapin, F. Stuart

doi:10.1098/rsta.2007.2036

Cited by 327 publications

(321 citation statements)

References 80 publications

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“…Previous research has also documented extensive methane release from Arctic lakes, primarily via ebullition, with significant spatial variability within and between lakes (6, 7). Methane in Arctic lakes forms by microbial production (methanogenesis) in the water column and/or within anaerobic lake sediments (8). However, it is possible that some fraction of the observed methane is not produced within the lakes but is rather transported to the lakes from external, landbased sources through subterranean groundwater discharge (SGD) (9) (Fig.…”

mentioning

confidence: 99%

Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

Paytan

Lecher

Dimova

et al. 2015

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

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Methane emissions in the Arctic are important, and may be contributing to global warming. While methane emission rates from Arctic lakes are well documented, methods are needed to quantify the relative contribution of active layer groundwater to the overall lake methane budget. Here we report measurements of natural tracers of soil/groundwater, radon, and radium, along with methane concentration in Toolik Lake, Alaska, to evaluate the role active layer water plays as an exogenous source for lake methane. Average concentrations of methane, radium, and radon were all elevated in the active layer compared with lake water (1.6 × 104 nM, 61.6 dpm⋅m−3, and 4.5 × 105 dpm⋅m−3 compared with 1.3 × 102 nM, 5.7 dpm⋅m−3, and 4.4 × 103 dpm⋅m−3, respectively). Methane transport from the active layer to Toolik Lake based on the geochemical tracer radon (up to 2.9 g⋅m−2⋅y−1) can account for a large fraction of methane emissions from this lake. Strong but spatially and temporally variable correlations between radon activity and methane concentrations (r2 > 0.69) in lake water suggest that the parameters that control methane discharge from the active layer also vary. Warming in the Arctic may expand the active layer and increase the discharge, thereby increasing the methane flux to lakes and from lakes to the atmosphere, exacerbating global warming. More work is needed to quantify and elucidate the processes that control methane fluxes from the active layer to predict how this flux might change in the future and to evaluate the regional and global contribution of active layer water associated methane inputs.

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confidence: 99%

Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

Paytan

Lecher

Dimova

et al. 2015

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

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“…Methane release from permafrost (Zimov et al 2006;Walter et al 2007), should it accelerate with global warming, could spoil the efforts to reduce CH 4 . Hansen & Sato (2004) argue that large release from methane hydrates is unlikely if additional global warming is kept under 18C, based on the fact that CH 4 increase was moderate during previous interglacial periods that were warmer than at present by up to 18C.…”

Section: Non-co 2 Forcingsmentioning

confidence: 99%

Climate change and trace gases

Hansen

Sato

Kharecha

et al. 2007

Phil. Trans. R. Soc. A.

356

272

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Palaeoclimate data show that the Earth's climate is remarkably sensitive to global forcings. Positive feedbacks predominate. This allows the entire planet to be whipsawed between climate states. One feedback, the 'albedo flip' property of ice/water, provides a powerful trigger mechanism. A climate forcing that 'flips' the albedo of a sufficient portion of an ice sheet can spark a cataclysm. Inertia of ice sheet and ocean provides only moderate delay to ice sheet disintegration and a burst of added global warming. Recent greenhouse gas (GHG) emissions place the Earth perilously close to dramatic climate change that could run out of our control, with great dangers for humans and other creatures. Carbon dioxide (CO 2 ) is the largest human-made climate forcing, but other trace constituents are also important. Only intense simultaneous efforts to slow CO 2 emissions and reduce non-CO 2 forcings can keep climate within or near the range of the past million years. The most important of the non-CO 2 forcings is methane (CH 4 ), as it causes the second largest human-made GHG climate forcing and is the principal cause of increased tropospheric ozone (O 3 ), which is the third largest GHG forcing. Nitrous oxide (N 2 O) should also be a focus of climate mitigation efforts. Black carbon ('black soot') has a high global warming potential (approx. 2000, 500 and 200 for 20, 100 and 500 years, respectively) and deserves greater attention. Some forcings are especially effective at high latitudes, so concerted efforts to reduce their emissions could preserve Arctic ice, while also having major benefits for human health, agricultural productivity and the global environment.

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“…Ebullition is considered a major mechanism for transporting methane from anoxic sediments to the surface water and eventually to the atmosphere (Walter et al 2007). We used a published model that describes methane bubble dissolution and stripping of dissolved gases in a stratified water column (McGinnis et al 2006) to test if ebullition in thermally stratified Lake Stechlin could explain the mid-water methane peak.…”

mentioning

confidence: 99%

Paradox reconsidered: Methane oversaturation in well‐oxygenated lake waters

Tang

Mcginnis

Frindte

et al. 2014

Limnology & Oceanography

118

144

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The widely reported paradox of methane oversaturation in oxygenated water challenges the prevailing paradigm that microbial methanogenesis only occurs under anoxic conditions. Using a combination of field sampling, incubation experiments, and modeling, we show that the recurring mid-water methane peak in Lake Stechlin, northeast Germany, was not dependent on methane input from the littoral zone or bottom sediment or on the presence of known micro-anoxic zones. The methane peak repeatedly overlapped with oxygen oversaturation in the seasonal thermocline. Incubation experiments and isotope analysis indicated active methane production, which was likely linked to photosynthesis and/or nitrogen fixation within the oxygenated water, whereas lessening of methane oxidation by light allowed accumulation of methane in the oxygen-rich upper layer. Estimated methane efflux from the surface water was up to 5 mmol m 22 d 21 . Mid-water methane oversaturation was also observed in nine other lakes that collectively showed a strongly negative gradient of methane concentration within 0-20% dissolved oxygen (DO) in the bottom water, and a positive gradient within $ 20% DO in the upper water column. Further investigation into the responsible organisms and biochemical pathways will help improve our understanding of the global methane cycle.

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Methane bubbling from northern lakes: present and future contributions to the global methane budget

Cited by 327 publications

References 80 publications

Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

Climate change and trace gases

Paradox reconsidered: Methane oversaturation in well‐oxygenated lake waters

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