Long-term effects of permafrost thaw

Zona, Donatella

doi:10.1038/537625a

Cited by 19 publications

(8 citation statements)

References 9 publications

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“…1c–f ). For example, from the four idealized bioenergy crop scenarios based on the composited cultivation map, warming effects in Alaska and northwestern Canada may cause greenhouse gas release from thawing permafrost 30 , 31 , while strong cooling effects in Eurasia, between 60°N and 80°N, may protect permafrost from thawing or reduce methane emissions from wetlands. Therefore, the biophysical effects of bioenergy crop cultivation do not only alter global temperature directly, but also induce secondary effects on natural greenhouse gas fluxes, which should also be taken into account when considering large-scale BECCS deployment.…”

Section: Discussionmentioning

confidence: 99%

Global cooling induced by biophysical effects of bioenergy crop cultivation

Wang

Ciais

et al. 2021

Nat Commun

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Bioenergy crop with carbon capture and storage (BECCS) is a key negative emission technology to meet carbon neutrality. However, the biophysical effects of widespread bioenergy crop cultivation on temperature remain unclear. Here, using a coupled atmosphere-land model with an explicit representation of lignocellulosic bioenergy crops, we find that after 50 years of large-scale bioenergy crop cultivation following plausible scenarios, global air temperature decreases by 0.03~0.08 °C, with strong regional contrasts and interannual variability. Over the cultivated regions, woody crops induce stronger cooling effects than herbaceous crops due to larger evapotranspiration rates and smaller aerodynamic resistance. At the continental scale, air temperature changes are not linearly proportional to the cultivation area. Sensitivity tests show that the temperature change is robust for eucalypt but more uncertain for switchgrass among different cultivation maps. Our study calls for new metrics to take the biophysical effects into account when assessing the climate mitigation capacity of BECCS.

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Section: Discussionmentioning

confidence: 99%

Global cooling induced by biophysical effects of bioenergy crop cultivation

Wang

Ciais

et al. 2021

Nat Commun

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“…The decomposition and net storage of organic carbon is controlled in large part by redox conditions in the active layer that are regulated by the availability of oxygen [2]. Permafrost affects redox conditions by confining soil water to the active layer, resulting in soil saturation and thus periodic or persistent soil anoxia [3,4]. Anoxic conditions develop when oxygen is consumed through biochemical processes (e.g., aerobic respiration) or geochemical reactions (e.g., iron oxidation) faster than it is introduced to the soil by diffusion, plant roots, or infiltrating rainwater [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…Redox conditions regulate the microbial decomposition of soil organic carbon into CH 4 or CO 2 by controlling microbial gene expression in response to oxygen availability [31]. Under anoxic conditions, organic carbon is degraded stepwise through anaerobic pathways of fermentation and acetogenesis that supply alcohols and organic acids as substrates for methanogenesis [32].…”

Section: Introductionmentioning

confidence: 99%

Rainfall Alters Permafrost Soil Redox Conditions, but Meta-Omics Show Divergent Microbial Community Responses by Tundra Type in the Arctic

2021

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Soil anoxia is common in the annually thawed surface (‘active’) layer of permafrost soils, particularly when soils are saturated, and supports anaerobic microbial metabolism and methane (CH4) production. Rainfall contributes to soil saturation, but can also introduce oxygen, causing soil oxidation and altering anoxic conditions. We simulated a rainfall event in soil mesocosms from two dominant tundra types, tussock tundra and wet sedge tundra, to test the impacts of rainfall-induced soil oxidation on microbial communities and their metabolic capacity for anaerobic CH4 production and aerobic respiration following soil oxidation. In both types, rainfall increased total soil O2 concentration, but in tussock tundra there was a 2.5-fold greater increase in soil O2 compared to wet sedge tundra due to differences in soil drainage. Metagenomic and metatranscriptomic analyses found divergent microbial responses to rainfall between tundra types. Active microbial taxa in the tussock tundra community, including bacteria and fungi, responded to rainfall with a decline in gene expression for anaerobic metabolism and a concurrent increase in gene expression for cellular growth. In contrast, the wet sedge tundra community showed no significant changes in microbial gene expression from anaerobic metabolism, fermentation, or methanogenesis following rainfall, despite an initial increase in soil O2 concentration. These results suggest that rainfall induces soil oxidation and enhances aerobic microbial respiration in tussock tundra communities but may not accumulate or remain in wet sedge tundra soils long enough to induce a community-wide shift from anaerobic metabolism. Thus, rainfall may serve only to maintain saturated soil conditions that promote CH4 production in low-lying wet sedge tundra soils across the Arctic.

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“…The soil moisture and the modification of the local hydrology are key controls of the permafrost degradation in response to climate changes (Liljedahl et al, ; Zona, ). Soil moisture impacts the latent heat exchange during seasonal freezing/thawing and the soil thermal properties that govern the magnitude of the heat flux in the ground during summer and winter.…”

Section: Introductionmentioning

confidence: 99%

Stability Conditions of Peat Plateaus and Palsas in Northern Norway

et al. 2019

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Peat plateaus and palsas are characteristic morphologies of sporadic permafrost, and the transition from permafrost to permafrost‐free ground typically occurs on spatial scales of meters. They are particularly vulnerable to climate change and are currently degrading in Fennoscandia. Here we present a spatially distributed data set of ground surface temperatures for two peat plateau sites in northern Norway for the year 2015–2016. Based on these data and thermal modeling, we investigate how the snow depth and water balance modulate the climate signal in the ground. We find that mean annual ground surface temperatures are centered around 2 to 2.5 °C for stable permafrost locations and 3.5 to 4.5 °C for permafrost‐free locations. The surface freezing degree days are characterized by a noticeable threshold around 200 °C.day, with most permafrost‐free locations ranging below this value and most stable permafrost ones above it. Freezing degree day values are well correlated to the March snow cover, although some variability is observed and attributed to the ground moisture level. Indeed, a zero curtain effect is observed on temperature time series for saturated soils during winter, while drained peat plateaus show early freezing surface temperatures. Complementarily, modeling experiments allow identifying a drainage effect that can modify 1‐m ground temperatures by up to 2 °C between drained and water accumulating simulations for the same snow cover. This effect can set favorable or unfavorable conditions for permafrost stability under the same climate forcing.

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Long-term effects of permafrost thaw

Cited by 19 publications

References 9 publications

Global cooling induced by biophysical effects of bioenergy crop cultivation

Global cooling induced by biophysical effects of bioenergy crop cultivation

Rainfall Alters Permafrost Soil Redox Conditions, but Meta-Omics Show Divergent Microbial Community Responses by Tundra Type in the Arctic

Stability Conditions of Peat Plateaus and Palsas in Northern Norway

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