scholarly journals Late-Holocene changes in character and behaviour of land-terminating glaciers on James Ross Island, Antarctica

2012 ◽  
Vol 58 (212) ◽  
pp. 1176-1190 ◽  
Author(s):  
Jonathan L. Carrivick ◽  
Bethan J. Davies ◽  
Neil F. Glasser ◽  
Daniel Nývlt ◽  
Michael J. Hambrey
Keyword(s):  
Climate Change ◽  
Sediment Transport ◽  
Surface Structure ◽  
Antarctic Peninsula ◽  
Thermal Regime ◽  
Late Holocene ◽  
Negative Mass ◽  
Warming Climate ◽  
James Ross Island ◽  
Geometric Changes

AbstractVirtually no information is available on the response of land-terminating Antarctic Peninsula glaciers to climate change on a centennial timescale. This paper analyses the topography, geomorphology and sedimentology of prominent moraines on James Ross Island, Antarctica, to determine geometric changes and to interpret glacier behaviour. The moraines are very likely due to a late-Holocene phase of advance and featured (1) shearing and thrusting within the snout, (2) shearing and deformation of basal sediment, (3) more supraglacial debris than at present and (4) short distances of sediment transport. Retreat of ~100 m and thinning of 15–20 m has produced a loss of 0.1 km3 of ice. The pattern of surface lowering is asymmetric. These geometrical changes are suggested most simply to be due to a net negative mass balance caused by a drier climate. Comparisons of the moraines with the current glaciological surface structure of the glaciers permits speculation of a transition from a polythermal to a cold-based thermal regime. Small land-terminating glaciers in the northern Antarctic Peninsula region could be cooling despite a warming climate.

Effect of summer snow cover on the active layer thermal regime and thickness on CALM-S JGM site, James Ross Island, eastern Antarctic Peninsula

CATENA ◽  
2021 ◽  
Vol 207 ◽  
pp. 105608
Author(s):  
Filip Hrbáček ◽  
Zbyněk Engel ◽  
Michaela Kňažková ◽  
Jana Smolíková
Keyword(s):  
Snow Cover ◽  
Active Layer ◽  
Antarctic Peninsula ◽  
Thermal Regime ◽  
James Ross Island

scholarly journals Effect of ephemeral snow cover on the active layer thermal regime and thickness on CALM-S JGM site, James Ross Island, eastern Antarctic Peninsula

2021 ◽  
Author(s):  
Filip Hrbáček ◽  
Zbyněk Engel ◽  
Michaela Kňažková ◽  
Jana Smolíková
Keyword(s):  
Snow Cover ◽  
Active Layer ◽  
Antarctic Peninsula ◽  
Thermal Regime ◽  
Austral Summer ◽  
Monitoring Network ◽  
Active Layer Thickness ◽  
Ground Temperatures ◽  
James Ross Island ◽  
Ground Penetrating

Abstract. This study aims to assess the role of ephemeral snow cover on ground thermal regime and active layer thickness in two ground temperature measurement profiles on the Circumpolar Active Layer Monitoring Network – South (CALM-S) JGM site on James Ross Island, eastern Antarctic Peninsula during the high austral summer 2018. The snowstorm of 13–14 January created a snowpack of recorded depth of up to 38 cm. The snowpack remained on the study site for 12 days in total and covered 46 % of its area six days after the snowfall. It directly affected ground thermal regime in a study profile AWS-JGM while the AWS-CALM profile was snow-free. The thermal insulation effect of snow cover led to a decrease of mean summer ground temperatures on AWS-JGM by ca 0.5–0.7 °C. Summer thawing degree days at a depth of 5 cm decreased by ca 10 % and active layer was ca 5–10 cm thinner when compared to previous snow-free summer seasons. Surveying by ground penetrating radar revealed a general active layer thinning of up to 20 % in those parts of the CALM-S which were covered by snow of > 20 cm depth for at least six days.

Modelling ecosystem adaptation and dangerous rates of global warming

2019 ◽  
Vol 3 (2) ◽  
pp. 221-231 ◽  
Author(s):  
Rebecca Millington ◽  
Peter M. Cox ◽  
Jonathan R. Moore ◽  
Gabriel Yvon-Durocher
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Diffusion Rate ◽  
Individual Species ◽  
Genetic Evolution ◽  
Rates Of Change ◽  
Rapid Climate Change ◽  
Warming Climate ◽  
Intraspecies Competition ◽  
High Trait

Abstract We are in a period of relatively rapid climate change. This poses challenges for individual species and threatens the ecosystem services that humanity relies upon. Temperature is a key stressor. In a warming climate, individual organisms may be able to shift their thermal optima through phenotypic plasticity. However, such plasticity is unlikely to be sufficient over the coming centuries. Resilience to warming will also depend on how fast the distribution of traits that define a species can adapt through other methods, in particular through redistribution of the abundance of variants within the population and through genetic evolution. In this paper, we use a simple theoretical ‘trait diffusion’ model to explore how the resilience of a given species to climate change depends on the initial trait diversity (biodiversity), the trait diffusion rate (mutation rate), and the lifetime of the organism. We estimate theoretical dangerous rates of continuous global warming that would exceed the ability of a species to adapt through trait diffusion, and therefore lead to a collapse in the overall productivity of the species. As the rate of adaptation through intraspecies competition and genetic evolution decreases with species lifetime, we find critical rates of change that also depend fundamentally on lifetime. Dangerous rates of warming vary from 1°C per lifetime (at low trait diffusion rate) to 8°C per lifetime (at high trait diffusion rate). We conclude that rapid climate change is liable to favour short-lived organisms (e.g. microbes) rather than longer-lived organisms (e.g. trees).

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