Rapid Early Development of Circumarctic Peatlands and Atmospheric CH
            <sub>4</sub>
            and CO
            <sub>2</sub>
            Variations

MacDonald, Glen M.; Beilman, David W.; Kremenetski, K. V.; Sheng, Yongwei; Smith, L. C.; Величко, А.А.

doi:10.1126/science.1131722

Cited by 368 publications

(391 citation statements)

References 29 publications

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“…Peatland initiation in the northern high latitudes began around 15,000 years ago, during the deglaciation. Almost half of the modern peatland began to form before 8,000 years ago 69 ; around 100 Pg of carbon were sequestered in the process, contributing to the observed drawdown of atmospheric CO 2 and the peak in atmospheric CH 4 in the early Holocene 70 . Increased peat-accumulation rates are registered during the warmer conditions of the early to mid-Holocene in the northern high latitudes 71 , whereas substantially reduced accumulation occurred during the cold intervals of the Younger Dryas and the Little Ice Age 72 .…”

Section: Past Links Between Biogeochemical Cycles and Climatementioning

confidence: 99%

Terrestrial biogeochemical feedbacks in the climate system

et al. 2010

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The terrestrial biosphere is a key regulator of atmospheric chemistry and climate. During past periods of climate change, vegetation cover and interactions between the terrestrial biosphere and atmosphere changed within decades. Modern observations show a similar responsiveness of terrestrial biogeochemistry to anthropogenically forced climate change and air pollution. Although interactions between the carbon cycle and climate have been a central focus, other biogeochemical feedbacks could be as important in modulating future climate change. Total positive radiative forcings resulting from feedbacks between the terrestrial biosphere and the atmosphere are estimated to reach up to 0.9 or 1.5 W m(-2) K-1 towards the end of the twenty-first century, depending on the extent to which interactions with the nitrogen cycle stimulate or limit carbon sequestration. This substantially reduces and potentially even eliminates the cooling effect owing to carbon dioxide fertilization of the terrestrial biota. The overall magnitude of the biogeochemical feedbacks could potentially be similar to that of feedbacks in the physical climate system, but there are large uncertainties in the magnitude of individual estimates and in accounting for synergies between these effects

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Section: Past Links Between Biogeochemical Cycles and Climatementioning

confidence: 99%

Terrestrial biogeochemical feedbacks in the climate system

et al. 2010

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“…There is debate, in particular, regarding the contribution of these sources to the rapid rises in methane observed during deglaciation [Brook et al, 2000]. For example, the change in the dD CH4 of atmospheric methane during the periods of rapid warming which follow cold periods such as the Younger Dryas is not consistent with a marine clathrate contribution [Sowers, 2006], and it is uncertain whether wetlands alone can explain the variation in atmospheric methane concentrations [Valdes et al, 2005] despite the hypothesized rapid increase in the productivity and area of wetlands during periods of climatic warming [Kaplan, 2002;MacDonald et al, 2006]. More recently, several studies have highlighted the potential role of the basal sediments of ice sheets as a potential source of methane during deglaciation [Zeng, 2003;Weitemeyer and Buffett, 2006].…”

Section: Introductionmentioning

confidence: 99%

“…Oceanic processes are thought to drive carbon dioxide variations [Flückiger et al, 2004], but the drive on methane variations is still a matter of conjecture. The expansion and contraction of northern and tropical wetlands may be a key control [Brook et al, 2000;Delmotte et al, 2004;Flückiger et al, 2004;MacDonald et al, 2006], as may the stability of marine and terrestrial clathrates [MacDonald, 1983[MacDonald, , 1990Nisbet, 1989Nisbet, , 1990Paull et al, 1991Paull et al, , 1994Kennett et al, 2003]. There is debate, in particular, regarding the contribution of these sources to the rapid rises in methane observed during deglaciation [Brook et al, 2000].…”

Section: Introductionmentioning

confidence: 99%

Subglacial methanogenesis: A potential climatic amplifier?

Wadham

Tranter

Tulaczyk

et al. 2008

Global Biogeochemical Cycles

114

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[1] Subglacial environments are a previously neglected component of the Earth's global carbon cycle, a reflection of the view held until recently that they are dominated by abiotic and oxic conditions. Here we provide a realistic assessment of the theory that the basal regions of the ice sheets that formed over North America and Europe during glaciations were host to significant populations of anaerobic microorganisms, including methanogens, able to metabolize organic carbon sequestered during interglacials and overridden during Quaternary glacials. In doing so, we review the current evidence for subglacial methane release during deglaciation, estimate the size of the subglacial reservoir of organic carbon (SOC), and assess the amount of SOC available to subglacial microbes and the likely pathways and rates of carbon turnover. We then discuss the fate of subglacial methane and the potential impact of its release on atmospheric methane concentrations. We calculate that the SOC equates to 418-610 Pg C and includes carbon from terrestrial soils/vegetation, peatlands, lake, and marine sediments. The SOC that is potentially available for microbial conversion to methane is smaller than this estimate due to (1) glacial erosion, (2) accumulation of recalcitrant organic carbon compounds over time, (3) conversion to carbon dioxide by aerobic/anaerobic respiration, and (4) incomplete conversion of labile organic matter to methane. We estimate that the total SOC available for conversion to methane is 63 Pg C. Our estimates of methane production potentials span a wide range because of the current uncertainty surrounding subglacial metabolic rates. We believe, however, that there is a strong likelihood that subglacial microbes could convert 63 Pg of SOC to methane during a glacial cycle. If this were the case, release of this methane from the ice sheet margins during retreat would need to be episodic in order to significantly impact atmospheric methane concentrations. Our findings suggest that it may well be important to consider subglacial environments as active components of the Earth's carbon cycle. Conclusive determination of the potential impact of subglacial methane production on atmospheric methane concentrations during deglaciation, however, awaits more precise determination of the ability of subglacial microbes to degrade organic carbon components and their associated rates of metabolism under in situ conditions.

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“…Eisner et al (2005) document an early phase of high productive plant growth at ca 8 kyr BP from an erosional remnant on the northern Arctic Coastal Plain. MacDonald et al (2006) correlate early peatland development on a circumarctic basis beginning around 16.5 kyr BP and expanding rapidly between 12 and 8 kyr BP. Numerous regional pollen records reflect a rapid transformation of the vegetation communities from herbdominated tundra to birch-dominated shrub tundra ca 14e12 kyr BP (e.g.…”

Section: Introductionmentioning

confidence: 99%

Lateglacial and Holocene isotopic and environmental history of northern coastal Alaska – Results from a buried ice-wedge system at Barrow

Meyer

Schirrmeister

Andreev

et al. 2010

Quaternary Science Reviews

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a b s t r a c tBarrow, the northernmost point in Alaska, is one of the most intensively studied areas in the Arctic. However, paleoenvironmental evidence is limited for northern Alaska for the LateglacialeHolocene transition. For a regional paleoenvironmental reconstruction, we investigated a permafrost ice-wedge tunnel near Barrow, Alaska. The studied site was first excavated in the early 1960s and intercepts a buried ice-wedge system at 3e6 m depth below the surface. A multi-methodological approach was applied to this buried ice-wedge system and the enclosing sediments, which in their combination, give new insight into the Late Quaternary environmental and climate history. Results of geochronological, sedimentological, cryolithological, paleoecological, isotope geochemical and microbiological studies reflect different stages of mid to late Wisconsin (MW to LW), Allerød (AD), Younger Dryas (YD), Preboreal (PB), and Late Holocene paleoenvironmental evolution. The LW age of the site is indicated by AMS dates in the surrounding sediments of 21.7 kyr BP at the lateral contact of the ice-wedge system as well as 39.5 kyr BP below the ice-wedge system. It is only recently that in this region, stable isotope techniques have been employed, i.e. to characterize different types of ground ice. The stable isotope record (oxygen: d 18 O; hydrogen: dD) of two intersecting ice wedges suggests different phases of the northern Alaskan climate history from AD to PB, with radiocarbon dates from 12.4 to 9.9 kyr BP (ranging from 14.8 to 10.6 kyr cal BP). Stable isotope geochemistry of ice wedges reveals winter temperature variations of the Lateglacial eHolocene transition including a prominent YD cold period, clearly separated from the warmer AD and PB phases. YD is only weakly developed in summer temperature indicators (such as pollen) for the northern Alaska area, and by consequence, the YD cold stadial was here especially related to the winter season. This highlights that the combination of winter and summer indicators comprehensively describes the seasonality of climate-relevant processes in discrete time intervals. The stable isotope record for the Barrow buried ice-wedge system documents for the first time winter climate change at the LateglacialeHolocene transition continuously and at relatively high (likely centennial) resolution.

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Rapid Early Development of Circumarctic Peatlands and Atmospheric CH ₄ and CO ₂ Variations

Cited by 368 publications

References 29 publications

Terrestrial biogeochemical feedbacks in the climate system

Terrestrial biogeochemical feedbacks in the climate system

Subglacial methanogenesis: A potential climatic amplifier?

Lateglacial and Holocene isotopic and environmental history of northern coastal Alaska – Results from a buried ice-wedge system at Barrow

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Rapid Early Development of Circumarctic Peatlands and Atmospheric CH 4 and CO 2 Variations

Cited by 368 publications

References 29 publications

Terrestrial biogeochemical feedbacks in the climate system

Terrestrial biogeochemical feedbacks in the climate system

Subglacial methanogenesis: A potential climatic amplifier?

Lateglacial and Holocene isotopic and environmental history of northern coastal Alaska – Results from a buried ice-wedge system at Barrow

Contact Info

Product

Resources

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Rapid Early Development of Circumarctic Peatlands and Atmospheric CH ₄ and CO ₂ Variations