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Li L, Xue B. Methane emissions from northern lakes under climate change: a review. SN APPLIED SCIENCES 2021. [DOI: 10.1007/s42452-021-04869-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
AbstractNorthern lakes are important sources of CH4 in the atmosphere under the background of permafrost thaw and winter warming. We synthesize studies on thermokarst lakes, including various carbon sources for CH4 emission and the influence of thermokarst drainage on carbon emission, to show the evasion potential of ancient carbon that stored in the permafrost and CH4 emission dynamics along with thermokarst lake evolution. Besides, we discuss the lake CH4 dynamics in seasonally ice-covered lakes, especially for under-ice CH4 accumulation and emission during spring ice melt and the possible influential factors for CH4 emission in ice-melt period. We summarize the latest findings and point out that further research should be conducted to investigate the possibility of abundant ancient carbon emission from thermokarst lakes under climate warming and quantify the contribution of ice-melt CH4 emission from northern lakes on a large scale.
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Geomorphological and Climatic Drivers of Thermokarst Lake Area Increase Trend (1999–2018) in the Kolyma Lowland Yedoma Region, North-Eastern Siberia. REMOTE SENSING 2021. [DOI: 10.3390/rs13020178] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Thermokarst lakes are widespread in Arctic lowlands. Under a warming climate, landscapes with highly ice-rich Yedoma Ice Complex (IC) deposits are particularly vulnerable, and thermokarst lake area dynamics serve as an indicator for their response to climate change. We conducted lake change trend analysis for a 44,500 km2 region of the Kolyma Lowland using Landsat imagery in conjunction with TanDEM-X digital elevation model and Quaternary Geology map data. We delineated yedoma–alas relief types with different yedoma fractions, serving as a base for geospatial analysis of lake area dynamics. We quantified lake changes over the 1999–2018 period using machine-learning-based classification of robust trends of multi-spectral indices of Landsat data and object-based long-term lake detection. We analyzed the lake area dynamics separately for 1999–2013 and 1999–2018 periods, including the most recent five years that were characterized by very high precipitation. Comparison of drained lake basin area with thermokarst lake extents reveal the overall limnicity decrease by 80% during the Holocene. Current climate warming and wetting in the region led to a lake area increase by 0.89% for the 1999–2013 period and an increase by 4.15% for the 1999–2018 period. We analyzed geomorphological factors impacting modern lake area changes for both periods such as lake size, elevation, and yedoma–alas relief type. We detected a lake area expansion trend in high yedoma fraction areas indicating ongoing Yedoma IC degradation by lake thermokarst. Our concept of differentiating yedoma–alas relief types helps to characterize landscape-scale lake area changes and could potentially be applied for refined assessments of greenhouse gas emissions in Yedoma regions. Comprehensive geomorphological inventories of Yedoma regions using geospatial data provide a better understanding of the extent of thermokarst processes during the Holocene and the pre-conditioning of modern thermokarst lake area dynamics.
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In 't Zandt MH, Liebner S, Welte CU. Roles of Thermokarst Lakes in a Warming World. Trends Microbiol 2020; 28:769-779. [PMID: 32362540 DOI: 10.1016/j.tim.2020.04.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 02/10/2020] [Accepted: 04/01/2020] [Indexed: 11/27/2022]
Abstract
Permafrost covers a quarter of the northern hemisphere land surface and contains twice the amount of carbon that is currently present in the atmosphere. Future climate change is expected to reduce its near-surface cover by over 90% by the end of the 21st century, leading to thermokarst lake formation. Thermokarst lakes are point sources of carbon dioxide and methane which release long-term carbon stocks into the atmosphere, thereby initiating a positive climate feedback potentially contributing up to a 0.39°C rise of surface air temperatures by 2300. This review describes the potential role of thermokarst lakes in a warming world and the microbial mechanisms that underlie their contributions to the global greenhouse gas budget.
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Affiliation(s)
- Michiel H In 't Zandt
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands; Netherlands Earth System Science Center, Utrecht University, Heidelberglaan 2, 3584 CS, Utrecht, the Netherlands
| | - Susanne Liebner
- GFZ German Research Centre for Geosciences, Section 3.7 Geomicrobiology, Telegrafenberg, 14473 Potsdam, Germany; University of Potsdam, Institute of Biochemistry and Biology, 14469 Potsdam, Germany
| | - Cornelia U Welte
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands; Soehngen Institute of Anaerobic Microbiology, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands.
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An Object-Based Classification Method to Detect Methane Ebullition Bubbles in Early Winter Lake Ice. REMOTE SENSING 2019. [DOI: 10.3390/rs11070822] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Thermokarst lakes in the Arctic and Subarctic release carbon from thawing permafrost in the form of methane and carbon dioxide with important implications for regional and global carbon cycles. Lake ice impedes the release of gas during the winter. For instance, bubbles released from lake sediments become trapped in downward growing lake ice, resulting in vertically-oriented bubble columns in the ice that are visible on the lake surface. We here describe a classification technique using an object-based image analysis (OBIA) framework to successfully map ebullition bubbles in airborne imagery of early winter ice on an interior Alaska thermokarst lake. Ebullition bubbles appear as white patches in high-resolution optical remote sensing images of snow-free lake ice acquired in early winter and, thus, can be mapped across whole lake areas. We used high-resolution (9–11 cm) aerial images acquired two and four days following freeze-up in the years 2011 and 2012, respectively. The design of multiresolution segmentation and region-specific classification rulesets allowed the identification of bubble features and separation from other confounding factors such as snow, submerged and floating vegetation, shadows, and open water. The OBIA technique had an accuracy of >95% for mapping ebullition bubble patches in early winter lake ice. Overall, we mapped 1195 and 1860 ebullition bubble patches in the 2011 and 2012 images, respectively. The percent surface area of lake ice covered with ebullition bubble patches for 2011 was 2.14% and for 2012 was 2.67%, representing a conservative whole lake estimate of bubble patches compared to ground surveys usually conducted on thicker ice 10 or more days after freeze-up. Our findings suggest that the information derived from high-resolution optical images of lake ice can supplement spatially limited field sampling methods to better estimate methane flux from individual lakes. The method can also be used to improve estimates of methane ebullition from numerous lakes within larger regions.
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Deglacial mobilization of pre-aged terrestrial carbon from degrading permafrost. Nat Commun 2018; 9:3666. [PMID: 30201999 PMCID: PMC6131488 DOI: 10.1038/s41467-018-06080-w] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 08/13/2018] [Indexed: 11/16/2022] Open
Abstract
The mobilization of glacial permafrost carbon during the last glacial–interglacial transition has been suggested by indirect evidence to be an additional and significant source of greenhouse gases to the atmosphere, especially at times of rapid sea-level rise. Here we present the first direct evidence for the release of ancient carbon from degrading permafrost in East Asia during the last 17 kyrs, using biomarkers and radiocarbon dating of terrigenous material found in two sediment cores from the Okhotsk Sea. Upscaling our results to the whole Arctic shelf area, we show by carbon cycle simulations that deglacial permafrost-carbon release through sea-level rise likely contributed significantly to the changes in atmospheric CO2 around 14.6 and 11.5 kyrs BP. Permafrost-derived carbon (C) may have been an additional source of greenhouse gases during the last glacial-interglacial transition. Here the authors show that ancient C from degrading permafrost was mobilised during phases of rapid sea-level rise, partially explaining changes in atmospheric CO2 and ∆14C.
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21st-century modeled permafrost carbon emissions accelerated by abrupt thaw beneath lakes. Nat Commun 2018; 9:3262. [PMID: 30111815 PMCID: PMC6093858 DOI: 10.1038/s41467-018-05738-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 07/17/2018] [Indexed: 12/01/2022] Open
Abstract
Permafrost carbon feedback (PCF) modeling has focused on gradual thaw of near-surface permafrost leading to enhanced carbon dioxide and methane emissions that accelerate global climate warming. These state-of-the-art land models have yet to incorporate deeper, abrupt thaw in the PCF. Here we use model data, supported by field observations, radiocarbon dating, and remote sensing, to show that methane and carbon dioxide emissions from abrupt thaw beneath thermokarst lakes will more than double radiative forcing from circumpolar permafrost-soil carbon fluxes this century. Abrupt thaw lake emissions are similar under moderate and high representative concentration pathways (RCP4.5 and RCP8.5), but their relative contribution to the PCF is much larger under the moderate warming scenario. Abrupt thaw accelerates mobilization of deeply frozen, ancient carbon, increasing 14C-depleted permafrost soil carbon emissions by ~125–190% compared to gradual thaw alone. These findings demonstrate the need to incorporate abrupt thaw processes in earth system models for more comprehensive projection of the PCF this century. Permafrost carbon feedback modeling has focused on gradual thaw of near-surface permafrost leading to greenhouse gas emissions that accelerate climate change. Here the authors show that deeper, abrupt thaw beneath lakes will more than double radiative forcing from permafrost-soil carbon fluxes this century.
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Bock M, Schmitt J, Beck J, Seth B, Chappellaz J, Fischer H. Glacial/interglacial wetland, biomass burning, and geologic methane emissions constrained by dual stable isotopic CH 4 ice core records. Proc Natl Acad Sci U S A 2017; 114:E5778-E5786. [PMID: 28673973 PMCID: PMC5530640 DOI: 10.1073/pnas.1613883114] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Atmospheric methane (CH4) records reconstructed from polar ice cores represent an integrated view on processes predominantly taking place in the terrestrial biogeosphere. Here, we present dual stable isotopic methane records [δ13CH4 and δD(CH4)] from four Antarctic ice cores, which provide improved constraints on past changes in natural methane sources. Our isotope data show that tropical wetlands and seasonally inundated floodplains are most likely the controlling sources of atmospheric methane variations for the current and two older interglacials and their preceding glacial maxima. The changes in these sources are steered by variations in temperature, precipitation, and the water table as modulated by insolation, (local) sea level, and monsoon intensity. Based on our δD(CH4) constraint, it seems that geologic emissions of methane may play a steady but only minor role in atmospheric CH4 changes and that the glacial budget is not dominated by these sources. Superimposed on the glacial/interglacial variations is a marked difference in both isotope records, with systematically higher values during the last 25,000 y compared with older time periods. This shift cannot be explained by climatic changes. Rather, our isotopic methane budget points to a marked increase in fire activity, possibly caused by biome changes and accumulation of fuel related to the late Pleistocene megafauna extinction, which took place in the course of the last glacial.
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Affiliation(s)
- Michael Bock
- Climate and Environmental Physics, Physics Institute, University of Bern, 3012 Bern, Switzerland;
- Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
| | - Jochen Schmitt
- Climate and Environmental Physics, Physics Institute, University of Bern, 3012 Bern, Switzerland
- Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
| | - Jonas Beck
- Climate and Environmental Physics, Physics Institute, University of Bern, 3012 Bern, Switzerland
- Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
| | - Barbara Seth
- Climate and Environmental Physics, Physics Institute, University of Bern, 3012 Bern, Switzerland
- Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
| | - Jérôme Chappellaz
- CNRS, IGE (Institut des Géosciences de l'Environnement), F-38000 Grenoble, France
- University of Grenoble Alpes, IGE, F-38000 Grenoble, France
- IRD (Institut de Recherche pour le Développement), IGE, F-38000 Grenoble, France
- Grenoble INP (Institut National Polytechnique), IGE, F-38000 Grenoble, France
| | - Hubertus Fischer
- Climate and Environmental Physics, Physics Institute, University of Bern, 3012 Bern, Switzerland;
- Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
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Stackpoole SM, Butman DE, Clow DW, Verdin KL, Gaglioti BV, Genet H, Striegl RG. Inland waters and their role in the carbon cycle of Alaska. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2017; 27:1403-1420. [PMID: 28376236 DOI: 10.1002/eap.1552] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 03/20/2017] [Accepted: 03/24/2017] [Indexed: 05/08/2023]
Abstract
The magnitude of Alaska (AK) inland waters carbon (C) fluxes is likely to change in the future due to amplified climate warming impacts on the hydrology and biogeochemical processes in high latitude regions. Although current estimates of major aquatic C fluxes represent an essential baseline against which future change can be compared, a comprehensive assessment for AK has not yet been completed. To address this gap, we combined available data sets and applied consistent methodologies to estimate river lateral C export to the coast, river and lake carbon dioxide (CO2 ) and methane (CH4 ) emissions, and C burial in lakes for the six major hydrologic regions in the state. Estimated total aquatic C flux for AK was 41 Tg C/yr. Major components of this total flux, in Tg C/yr, were 18 for river lateral export, 17 for river CO2 emissions, and 8 for lake CO2 emissions. Lake C burial offset these fluxes by 2 Tg C/yr. River and lake CH4 emissions were 0.03 and 0.10 Tg C/yr, respectively. The Southeast and South central regions had the highest temperature, precipitation, terrestrial net primary productivity (NPP), and C yields (fluxes normalized to land area) were 77 and 42 g C·m-2 ·yr-1 , respectively. Lake CO2 emissions represented over half of the total aquatic flux from the Southwest (37 g C·m-2 ·yr-1 ). The North Slope, Northwest, and Yukon regions had lesser yields (11, 15, and 17 g C·m2 ·yr-1 ), but these estimates may be the most vulnerable to future climate change, because of the heightened sensitivity of arctic and boreal ecosystems to intensified warming. Total aquatic C yield for AK was 27 g C·m-2 ·yr-1 , which represented 16% of the estimated terrestrial NPP. Freshwater ecosystems represent a significant conduit for C loss, and a more comprehensive view of land-water-atmosphere interactions is necessary to predict future climate change impacts on the Alaskan ecosystem C balance.
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Affiliation(s)
- Sarah M Stackpoole
- U.S. Geological Survey, National Research Program, Denver Federal Center, MS413, Denver, Colorado, 80225, USA
| | - David E Butman
- National Research Program, U.S. Geological Survey, 3215 Marine Street, Boulder, Colorado, 80303, USA
- School of Environmental and Forest Sciences and Civil & Environmental Engineering, University of Washington - Seattle, Box 325100, Seattle, Washington, 98195, USA
| | - David W Clow
- U.S. Geological Survey, Colorado Water Science Center, Denver Federal Center, MS415, Denver, Colorado, 80225, USA
| | - Kristine L Verdin
- U.S. Geological Survey, Colorado Water Science Center, Denver Federal Center, MS415, Denver, Colorado, 80225, USA
| | - Benjamin V Gaglioti
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, Alaska, 99508, USA
- Tree Ring Lab, Lamont-Doherty Earth Observatory, 61 Route 9W - PO Box 1000, Palisades, New York, 10964, USA
| | - Hélène Genet
- Institute of Arctic Biology, University of Alaska - Fairbanks, 902 Koyukuk Drive, Fairbanks, Alaska, 99775, USA
| | - Robert G Striegl
- National Research Program, U.S. Geological Survey, 3215 Marine Street, Boulder, Colorado, 80303, USA
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Gao Z, Niu F, Wang Y, Luo J, Lin Z. Impact of a thermokarst lake on the soil hydrological properties in permafrost regions of the Qinghai-Tibet Plateau, China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 574:751-759. [PMID: 27664762 DOI: 10.1016/j.scitotenv.2016.09.108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 09/13/2016] [Accepted: 09/13/2016] [Indexed: 06/06/2023]
Abstract
The formation of thermokarst lakes can degrade alpine meadow ecosystems through changes in soil water and heat properties, which might have an effect on the regional surface water and groundwater processes. In this study, a typical thermokarst lake was selected in the Qinghai-Tibet Plateau (QTP), and the ecological index (SL) was used to divide the affected areas into extremely affected, severely affected, medium-affected, lightly affected, and non-affected areas, and soil hydrological properties, including saturated hydraulic conductivity and soil water-holding capacity, were investigated. The results showed that the formation of a thermokarst lake can lead to the degradation of alpine meadows, accompanied by a change in the soil physiochemical and hydrological properties. Specifically, the soil structure turned towards loose soil and the soil nutrients decreased from non-affected areas to severely affected areas, but the soil organic matter and available potassium increased slightly in the extremely affected areas. Soil saturated hydraulic conductivity showed a 1.7- to 4.1-fold increase in the lake-surrounding areas, and the highest value (401.9cmd-1) was detected in the severely affected area. Soil water-holding capacity decreased gradually during the transition from the non-affected areas to the severely affected areas, but it increased slightly in the extremely affected areas. The principal component analysis showed that the plant biomass was vital to the changes in soil hydrological properties. Thus, the vegetation might serve as a link between the thermokarst lake and soil hydrological properties. In this particular case, it was concluded that the thermokarst lake adversely affected the regional hydrological services in the alpine ecosystem. These results would be useful for describing appropriate hydraulic parameters with the purpose of modeling soil water transportation more accurately in the Qinghai-Tibet Plateau.
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Affiliation(s)
- Zeyong Gao
- State Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China; College of Earth and Environment Sciences, Lanzhou University, Lanzhou 730000, China
| | - Fujun Niu
- State Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China.
| | - Yibo Wang
- College of Earth and Environment Sciences, Lanzhou University, Lanzhou 730000, China
| | - Jing Luo
- State Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Zhanju Lin
- State Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China
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Climate change and the permafrost carbon feedback. Nature 2015; 520:171-9. [DOI: 10.1038/nature14338] [Citation(s) in RCA: 1830] [Impact Index Per Article: 203.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 02/12/2015] [Indexed: 11/08/2022]
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Anthony KMW, Zimov SA, Grosse G, Jones MC, Anthony PM, Chapin FS, Finlay JC, Mack MC, Davydov S, Frenzel P, Frolking S. A shift of thermokarst lakes from carbon sources to sinks during the Holocene epoch. Nature 2014; 511:452-6. [PMID: 25043014 DOI: 10.1038/nature13560] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Accepted: 06/02/2014] [Indexed: 11/09/2022]
Abstract
Thermokarst lakes formed across vast regions of Siberia and Alaska during the last deglaciation and are thought to be a net source of atmospheric methane and carbon dioxide during the Holocene epoch. However, the same thermokarst lakes can also sequester carbon, and it remains uncertain whether carbon uptake by thermokarst lakes can offset their greenhouse gas emissions. Here we use field observations of Siberian permafrost exposures, radiocarbon dating and spatial analyses to quantify Holocene carbon stocks and fluxes in lake sediments overlying thawed Pleistocene-aged permafrost. We find that carbon accumulation in deep thermokarst-lake sediments since the last deglaciation is about 1.6 times larger than the mass of Pleistocene-aged permafrost carbon released as greenhouse gases when the lakes first formed. Although methane and carbon dioxide emissions following thaw lead to immediate radiative warming, carbon uptake in peat-rich sediments occurs over millennial timescales. We assess thermokarst-lake carbon feedbacks to climate with an atmospheric perturbation model and find that thermokarst basins switched from a net radiative warming to a net cooling climate effect about 5,000 years ago. High rates of Holocene carbon accumulation in 20 lake sediments (47 ± 10 grams of carbon per square metre per year; mean ± standard error) were driven by thermokarst erosion and deposition of terrestrial organic matter, by nutrient release from thawing permafrost that stimulated lake productivity and by slow decomposition in cold, anoxic lake bottoms. When lakes eventually drained, permafrost formation rapidly sequestered sediment carbon. Our estimate of about 160 petagrams of Holocene organic carbon in deep lake basins of Siberia and Alaska increases the circumpolar peat carbon pool estimate for permafrost regions by over 50 per cent (ref. 6). The carbon in perennially frozen drained lake sediments may become vulnerable to mineralization as permafrost disappears, potentially negating the climate stabilization provided by thermokarst lakes during the late Holocene.
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Affiliation(s)
- K M Walter Anthony
- Water and Environmental Research Center, University of Alaska, Fairbanks, Alaska 99775-5860, USA
| | - S A Zimov
- Northeast Scientific Station, Pacific Institute for Geography, Far-East Branch, Russian Academy of Sciences, Cherskii 678830, Russia
| | - G Grosse
- 1] Geophysical Institute, University of Alaska, Fairbanks, Alaska 99775-7320, USA [2] Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Potsdam 14473, Germany
| | - M C Jones
- 1] Water and Environmental Research Center, University of Alaska, Fairbanks, Alaska 99775-5860, USA [2] US Geological Survey, Reston, Virginia 20192, USA
| | - P M Anthony
- Water and Environmental Research Center, University of Alaska, Fairbanks, Alaska 99775-5860, USA
| | - F S Chapin
- Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775-7000, USA
| | - J C Finlay
- Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, Minnesota 55108, USA
| | - M C Mack
- Department of Biology, University of Florida, Gainesville, Florida 32611, USA
| | - S Davydov
- Northeast Scientific Station, Pacific Institute for Geography, Far-East Branch, Russian Academy of Sciences, Cherskii 678830, Russia
| | - P Frenzel
- Max Planck Institute for Terrestrial Microbiology, Marburg 35043, Germany
| | - S Frolking
- Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, New Hampshire 03824-3525, USA
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Zimov S, Zimov N. Role of megafauna and frozen soil in the atmospheric CH4 dynamics. PLoS One 2014; 9:e93331. [PMID: 24695117 PMCID: PMC3973675 DOI: 10.1371/journal.pone.0093331] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2012] [Accepted: 03/05/2014] [Indexed: 11/19/2022] Open
Abstract
Modern wetlands are the world’s strongest methane source. But what was the role of this source in the past? An analysis of global 14C data for basal peat combined with modelling of wetland succession allowed us to reconstruct the dynamics of global wetland methane emission through time. These data show that the rise of atmospheric methane concentrations during the Pleistocene-Holocene transition was not connected with wetland expansion, but rather started substantially later, only 9 thousand years ago. Additionally, wetland expansion took place against the background of a decline in atmospheric methane concentration. The isotopic composition of methane varies according to source. Owing to ice sheet drilling programs past dynamics of atmospheric methane isotopic composition is now known. For example over the course of Pleistocene-Holocene transition atmospheric methane became depleted in the deuterium isotope, which indicated that the rise in methane concentrations was not connected with activation of the deuterium-rich gas clathrates. Modelling of the budget of the atmospheric methane and its isotopic composition allowed us to reconstruct the dynamics of all main methane sources. For the late Pleistocene, the largest methane source was megaherbivores, whose total biomass is estimated to have exceeded that of present-day humans and domestic animals. This corresponds with our independent estimates of herbivore density on the pastures of the late Pleistocene based on herbivore skeleton density in the permafrost. During deglaciation, the largest methane emissions originated from degrading frozen soils of the mammoth steppe biome. Methane from this source is unique, as it is depleted of all isotopes. We estimated that over the entire course of deglaciation (15,000 to 6,000 year before present), soils of the mammoth steppe released 300–550 Pg (1015 g) of methane. From current study we conclude that the Late Quaternary Extinction significantly affected the global methane cycle.
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Affiliation(s)
- Sergey Zimov
- Northeast Science Station, Pacific Institute for Geography, Russian Academy of Sciences, Cherskii, Russia
- * E-mail:
| | - Nikita Zimov
- Northeast Science Station, Pacific Institute for Geography, Russian Academy of Sciences, Cherskii, Russia
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Negandhi K, Laurion I, Whiticar MJ, Galand PE, Xu X, Lovejoy C. Small thaw ponds: an unaccounted source of methane in the Canadian high Arctic. PLoS One 2013; 8:e78204. [PMID: 24236014 PMCID: PMC3827239 DOI: 10.1371/journal.pone.0078204] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 09/09/2013] [Indexed: 11/18/2022] Open
Abstract
Thawing permafrost in the Canadian Arctic tundra leads to peat erosion and slumping in narrow and shallow runnel ponds that surround more commonly studied polygonal ponds. Here we compared the methane production between runnel and polygonal ponds using stable isotope ratios, ¹⁴C signatures, and investigated potential methanogenic communities through high-throughput sequencing archaeal 16S rRNA genes. We found that runnel ponds had significantly higher methane and carbon dioxide emissions, produced from a slightly larger fraction of old carbon, compared to polygonal ponds. The methane stable isotopic signature indicated production through acetoclastic methanogenesis, but gene signatures from acetoclastic and hydrogenotrophic methanogenic Archaea were detected in both polygonal and runnel ponds. We conclude that runnel ponds represent a source of methane from potentially older C, and that they contain methanogenic communities able to use diverse sources of carbon, increasing the risk of augmented methane release under a warmer climate.
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Affiliation(s)
- Karita Negandhi
- Centre for Northern Studies (CEN) and Institut national de la recherche scientifique, Centre Eau Terre Environnement, Quebec, Canada
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Kessler MA, Plug LJ, Walter Anthony KM. Simulating the decadal- to millennial-scale dynamics of morphology and sequestered carbon mobilization of two thermokarst lakes in NW Alaska. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jg001796] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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