(Un)frozen in Time

Nelson, Frederick E.

doi:10.1126/science.1081111

Cited by 124 publications

(34 citation statements)

References 14 publications

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“…The observed evidence shows that climate change has an impact on different natural and biological systems [1] , such as glacier retreat [2] , permafrost melt [3][4][5] , and extension of growing season in the middle and high latitude regions [6] . The second article of United Nation Framework for Convention on Climate Change (UNFCCC) is that "the ultimate objective of this Convention and any related legal instruments that the Conference of the Parties may adopt is to achieve, in accordance with the relevant provisions of the Convention, stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.…”

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confidence: 99%

Ecosystem vulnerability of China under B2 climate scenario in the 21st century

Dai

Huang

et al. 2007

CHINESE SCI BULL

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This paper applies climate change scenarios in China based on the SRES assumptions with the help of RCMs projections by PRECIS (providing regional climates for impacts studies) system introduced to China from the Hadley Centre for Climate Prediction and Research at a high-resolution (50 km×50 km) over China. This research focuses on B2 scenario of SRES. A biogeochemical model "Atmosphere Vegetation Integrated Model (AVIM2)" was applied to simulating ecosystem status in the 21st century. Then vulnerability of ecosystems was assessed based on a set of index of mainly net primary production (NPP) of vegetation. Results show that climate change would affect ecosystem of China severely and there would be a worse trend with the lapse of time. The regions where having vulnerable ecological background would have heavier impacts while some regions with better ecological backgroundwould also receive serious impacts. Extreme climate even would bring about worse impact on the ecosystems. Open shrub and desert steppe would be the two most affected types. When the extreme events happen, vulnerable ecosystem would extend to part of defoliate broad-leaved forest, woody grassland and evergreen conifer forest. Climate change would not always be negative. It could be of some benefit to cold region during the near-term. However, in view of mid-term to long-term negative impact on ecosystem vulnerability would be enormously.

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confidence: 99%

Ecosystem vulnerability of China under B2 climate scenario in the 21st century

Dai

Huang

et al. 2007

CHINESE SCI BULL

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“…vegetation, snow cover, and water 7 . Many studies have presented the thermal effects of local-scale surface cover on the active layer processes, e.g., the hydrothermal regimes and ground freezing-thawing in the active layer, active layer thickness, and thermal states of permafrost 3, 8–11 .…”

Section: Introductionmentioning

confidence: 99%

No protection of permafrost due to desertification on the Qinghai–Tibet Plateau

Wang

Jin

2017

Sci Rep

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Desertification of tundra regions may form an escalating cycle with permafrost degradation where more permafrost thaw leads to continued desertification. This traditional viewpoint has been challenged in recent reports that state desertification protects the underlying permafrost. However, our measurements of soil temperature from nine sites in the Honglianghe River Basin, interior QinghaiTibet Plateau, show that desertification can degrade permafrost. If one compares the permafrost temperatures at sites with thin sand covers (e.g. site Yu-7, permafrost temperature of −0.64 °C; site Yu-6, permafrost temperature of −1.15 °C) with that of site Xie-1 (−0.65 °C, with a 120-cm-thick sand cover), the permafrost temperature is not significantly different. It is clear that a thick sand cover does not influence the underlying permafrost temperature. Our observations support traditional geocryological knowledge which states that, under most circumstances, desertification does not protect, but rather degrades, permafrost.Permafrost is defined as ground that remains continuously at or below 0 °C for at least two consecutive years 1 . Permafrost is a product of long-term energy exchange between the ground surface and atmosphere and is therefore a condition of ground climate 2 . The difference in the macro-scale distribution of permafrost is controlled by the climate 3 ; however, the difference in the local conditions, such as the topography, vegetation, snow cover, soil and geological conditions, can significantly modify the thermal impacts of the climate 4-6 and result in local-scale anomalies in permafrost distribution 3 . One of the local-scale factors influencing permafrost distribution is dominantly surface cover, e.g. vegetation, snow cover, and water 7 . Many studies have presented the thermal effects of local-scale surface cover on the active layer processes, e.g., the hydrothermal regimes and ground freezing-thawing in the active layer, active layer thickness, and thermal states of permafrost 3,[8][9][10][11] . However, little focus has been placed on the hydrothermal impacts of desertification (sand layer or dune formation over the frozen ground) on the thermal regimes of soils in the active layer and the underlying permafrost.Permafrost underlies approximately 70% of the land area of the Qinghai-Tibet Plateau (QTP), the highest and most extensive plateau permafrost on Earth 12-14 . Observational evidence demonstrates that warming, thawing and degrading of the plateau permafrost has occurred during the past few decades 11,13,[15][16][17][18][19] . The effect of permafrost degradation in the Qinghai-Tibet Plateau dries the ground surfaces because the active layer usually thickens, the permafrost table lowers and vegetation becomes more fragmented and sparse. The result is an increase in wind action, enhanced deflation and Aeolian deposition, and increased potential risk of desertification 16,[20][21][22] . Since the 1960s, grassland deterioration and desertification have occurred in some parts of the QTP 23-25 and N...

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“…The total volume and extent of the sea ice are decreasing (Walsh, 2008) leading to an increase of river runoff (Peterson et al, 2002) and a decrease in the surface layer salinity of the Arctic Ocean (ACIA, 2005). An additional consequence is the accelerating permafrost melting (Nelson, 2003) and coastal erosion (Rachold et al, 2000). The increasing delivery of organic carbon is suspected to enhance the mineralization process carried out by heterotrophic bacteria in the estuarine and coastal Arctic Ocean (Meon and Amon, 2004) and thus release a large amount of CO 2 into the atmosphere (Kling et al, 1991).…”

Section: Potential Impact Of Global Changementioning

confidence: 99%

Diversity of Arctic pelagic <i>Bacteria</i> with an emphasis on photoheterotrophs: a review

2014

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Abstract. The Arctic Ocean is a unique marine environment with respect to seasonality of light, temperature, perennial ice cover, and strong stratification. Other important distinctive features are the influence of extensive continental shelves and its interactions with Atlantic and Pacific water masses and freshwater from sea ice melt and rivers. These characteristics have major influence on the biological and biogeochemical processes occurring in this complex natural system. Heterotrophic bacteria are crucial components of marine food webs and have key roles in controlling carbon fluxes in the oceans. Although it was previously thought that these organisms relied on the organic carbon in seawater for all of their energy needs, several recent discoveries now suggest that pelagic bacteria can depart from a strictly heterotrophic lifestyle by obtaining energy through unconventional mechanisms that are linked to the penetration of sunlight into surface waters. These photoheterotrophic mechanisms may play a significant role in the energy budget in the euphotic zone of marine environments. Modifications of light and carbon availability triggered by climate change may favor the photoheterotrophic lifestyle. Here we review advances in our knowledge of the diversity of marine photoheterotrophic bacteria and discuss their significance in the Arctic Ocean gained in the framework of the Malina cruise.

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(Un)frozen in Time

Cited by 124 publications

References 14 publications

Ecosystem vulnerability of China under B2 climate scenario in the 21st century

Ecosystem vulnerability of China under B2 climate scenario in the 21st century

No protection of permafrost due to desertification on the Qinghai–Tibet Plateau

Diversity of Arctic pelagic <i>Bacteria</i> with an emphasis on photoheterotrophs: a review

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(Un)frozen in Time

Cited by 124 publications

References 14 publications

Ecosystem vulnerability of China under B2 climate scenario in the 21st century

Ecosystem vulnerability of China under B2 climate scenario in the 21st century

No protection of permafrost due to desertification on the Qinghai–Tibet Plateau

Diversity of Arctic pelagic &lt;i&gt;Bacteria&lt;/i&gt; with an emphasis on photoheterotrophs: a review

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Diversity of Arctic pelagic <i>Bacteria</i> with an emphasis on photoheterotrophs: a review