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- Postglacial landscape changes and cryogenic processes in the Picos de Europa (Northern Spain): reconstructed from geomorphological mapping and microstructures on quartz grainsPublication . Nieuwendam, Alexandre; Ruiz-Fernández, Jesús; Oliva, Marc; Lopes, Vera; Cruces, Anabela; da Conceição Freitas, MariaA 5.4m long sediment core was collected from Belbín, a karstic depression dammed by a moraine in a mid-altitude environment in the Western Massif of the Picos de Europa of the Cantabrian Mountains, northern Spain. 14C AMS dating of the basal sediments in the core suggests that the maximum glacier advance during the last glacial cycle preceded the global Last Glacial Maximum and occurred prior to 37.2 ka cal BP. Four environmental stages are reconstructed from analysis of the sediment core and in particular the surface microstructures on quartz sand grains: (1) 37.2–29.4 ka was characterised by intense periglacial activity with deposition of slope deposits; (2) 29.4–22.6 ka saw the gradual infilling of the depression with sediment; (3) 22.6–8.1 ka was associated with a palaeolake; and (4) since 8.1 ka, terrestrialisation of the palaeolake commenced, and human impact related to fire activity started around 4.9 ka. Microstructures on the surface of quartz grains suggest different intensity patterns of frost weathering processes in response to Late Quaternary climate oscillations.
- Ground temperature and permafrost distribution in Hurd Peninsula (Livingston Island, Maritime Antarctic): an assessment using freezing indexes and TTOP modellingPublication . Ferreira, Alice; Vieira, Goncalo; Ramos, Miguel; Nieuwendam, AlexandreThe Western Antarctic Peninsula region shows mean annual air temperatures ranging from −4 to −2 °C. Due to its proximity to the climatic threshold of permafrost, and evidence of recent changes in regional air temperatures, this is a crucial area to analyse climate-ground interactions. Freezing indexes and n-factors from contrasting topographic locations in Hurd Peninsula (Livingston Island) are analysed to assess the influence of snow cover on soil's thermal regime. The snow pack duration, thickness and physical properties are key in determining the thermal characteristics and spatial distribution of permafrost. The Temperature at the Top Of the Permafrost (TTOP) model uses freezing and thawing indexes, n-factors and thermal conductivity of the ground, as factors representing ground-atmosphere interactions and provides a framework to understand permafrost conditions and distribution. Eight sites were used to calculate TTOP and evaluate its accuracy. They encompass different geological, morphological and climatic conditions selected to identify site-specific ground thermal regime controls. Data was collected in the freezing seasons of 2007 and 2009 for air, surface and ground temperatures, as well as snow thickness. TTOP model results from sites located between 140 and 275 m a.s.l were very close to observational data, with differences varying from 0.05 to 0.4 °C, which are smaller than instrumental error. TTOP results for 36 m a.s.l confirm that permafrost is absent at low altitude and thermal offsets for rock areas show values between 0.01 and 0.48 °C indicating a small effect of latent heat, as well as of advection.
- Glacial and Periglacial Landscapes of the Serra da EstrelaPublication . Vieira, Gonçalo; Nieuwendam, AlexandreThe Serra da Estrela is a granite-dominated plateau mountain located in Central Portugal, reaching an elevation of 1993 m. Its position in the western part of the Iberian Central System, elongated morphology in an SW–NE direction, generates an important barrier to the moist Atlantic air masses when they move into Iberia’s interior. This orographic rainfall effect is important today, as it was in the Pleistocene, generating high amounts of precipitation, which in the Pleistocene were key for glacier development. The presence of a plateau above 1400 m and a regional equilibrium line altitude at about 1650 m were key for the development of a plateau ice field, very sensitive to small climate oscillations, but responsible for the development of several radiating valley glaciers. The effects of this glacial system on the landscape were remarkable, with the development of numerous landforms and deposits, which are rare in such a geographical setting. The main geomorphological highlights are the erosional landscape of the western plateau, as well as the glaciated section of the Zêzere valley, which under the action of 11.3 km long and over 340 m thick glacier, developed impressive glacial features. The periglacial action occurred mainly in the non-glaciated parts of the plateaus and valley slopes and testify the significance of frost action all over the mountain, with the presence of permafrost at the plateaus and sites above about 1300 m.
- Spatial and temporal variability of periglaciation of the Iberian PeninsulaPublication . Oliva, Marc; Serrano, E.; Gómez-Ortiz, A.; González-Amuchastegui, M.J.; Nieuwendam, Alexandre; Palacios, D.; Pérez-Alberti, A.; Pellitero-Ondicol, R.; Ruiz-Fernández, J.; Valcárcel, M.; Vieira, Goncalo; Antoniades, D.Active periglacial processes are currently marginal in the Iberian Peninsula, spatially limited to the highest mountain ranges. However, a wide variety of periglacial deposits and landforms are distributed in low and mid-altitude environments, which shows evidence of past periods of enhanced periglacial activity. The purpose of this paper is to summarize the present knowledge of past periglacial activity in the Iberian Peninsula. The chronological framework takes four main stages into account: the last glaciation, deglaciation, Holocene and present-day processes. This study focuses on the highest massifs (Pyrenees, Cantabrian Range, NW ranges, Central Range, Iberian Range, Sierra Nevada) as well as other lower elevation environments, namely the central Iberian Meseta. During the last glaciation the periglacial belt extended to much lower altitudes than today, reaching current sea level in the NW corner of the Iberian Peninsula. A wide range of geomorphological landforms and sedimentary records is indicative of very active periglacial processes during that phase, in some cases related to permafrost conditions (i.e., block streams, rock glaciers). Most of the inactive landforms and deposits in low and mid-elevations in Iberia are also related to this phase. The massive deglaciation of the Iberian massifs was caused by a gradual increase in temperatures. The deglaciation phase was only interrupted by a short period with colder conditions (the Younger Dryas) that reactivated periglacial processes in the formerly glaciated cirques of the highest lands, specifically with the widespread development of rock glaciers. During the Holocene, periglacial processes have been only active in the highest ranges, shifting in altitude according to temperature regimes and moisture conditions. The Little Ice Age saw the reactivation of periglacial activity in lower elevations than today. Currently, periglacial processes are only active in elevations exceeding 2500 m in the southern ranges and above 2000e2200 m in the northern massifs, higher in Sierra Nevada, in the south of Iberian Peninsula.
- Active layer thermal regime at different vegetation covers at Lions Rump, King George Island, Maritime AntarcticaPublication . Almeida, Ivan C. C.; Schaefer, Carlos Ernesto G.R.; Fernandes, Raphael B.A.; Pereira, Thiago T.C.; Nieuwendam, Alexandre; Pereira, Antônio BatistaClimate change impacts the biotic and abiotic components of polar ecosystems, affecting the stability of permafrost, active layer thickness, vegetation, and soil. This paper describes the active layer thermal regimes of two adjacent shallow boreholes, under the same soil but with two different vegetations. The study is location in Lions Rump, at King George Island, Maritime Antarctic, one of the most sensitive regions to climate change, located near the climatic limit of Antarctic permafrost. Both sites are a Turbic Cambic Cryosol formed on andesitic basalt, one under moss vegetation (Andreaea gainii, at 85 m a.s.l.) and another under lichen (Usnea sp., at 86 m a.s.l.), located 10 m apart. Ground temperature at same depths (10, 30 and 80 cm), water content at 80 cm depth and air temperature were recorded hourly between March 2009 and February 2011. The two sites showed significant differences inmean annual ground temperature for all depths. The lichen site showed a higher soil temperature amplitude compared to the moss site, with ground surface (10 cm) showing the highest daily temperature in January 2011 (7.3 °C) and the lowest daily temperature in August (−16.5 °C). The soil temperature at the lichen site closely followed the air temperature trend. Themoss site showed a higherwater content at the bottommost layer, consistent with the water-saturated, low landscape position. The observed thermal buffering effect under mosses is primarily associatedwith highermoisture onsite, but a longer duration of the snowpack (not monitored) may also have influenced the results. Active layer thickness was approximately 150 cm at low-lyingmoss site, and 120 cm at well-drained lichen site. This allows to classify these soils as Cryosols (WRB) or Gelisols (Soil Taxonomy), with evident turbic features.
- Cryogenic processes and fire activity in a high Atlantic mountain area in NW Iberia (Picos de Europa) during the Mid–Late HolocenePublication . Ruiz-Fernández, Jesús; Nieuwendam, Alexandre; Oliva, Marc; Lopes, Vera; Cruces, Anabela; Freitas, Maria Conceição; Janeiro, Ana I.; López-Sáez, José AntonioMid-Late Holocene environmental changes in the Cantabrian Mountains are a consequence of both climate variability and human activity. A 182cm-long sedimentary sequence was collected from Belbín depression, Western Massif of Picos de Europa (Cantabrian Mountains, NW Spain), in order to reconstruct Holocene environmental dynamics and the factors triggering landscape changes in the area. Using multi-proxy analysis of the uppermost 60cm of the sediments (texture, organic matter content, quartz grains microstructures, charcoal deposition) together with three (14)C AMS dates, a sequence of alternating warmer and colder phases has been inferred for the last ca. 6.7kycalBP. Warm stages are defined by low to moderate chemical weathering of the quartz grain particles with relative increases of the C/N ratio, while colder phases show a moderate to intense physical weathering of the quartz grains and lower C/N ratios. Warmer temperatures were recorded in Belbín area between: 6.7-5, 3.7-3, 2.6-1.1, 0.87-0.51 and since 0.01kycalBP. A colder regime occurred between 5-3.7, 3-2.6, 1.1-0.87 and 0.51 to 0.01kycalBP. The increasing organic matter content during the Late Holocene may be associated with increasing temperatures. The charcoal particles do not show a higher or lower concentration during prevailing colder or warmer conditions, and therefore may be linked to human-induced fire management of the landscape. The most intense period with fire activity occurred between 3.5 and 3kycalBP during the Bronze Age.
- Brief communication: future avenues for permafrost science from the perspective of early career researchersPublication . Fritz, M.; Deshpande, B. N.; Bouchard, F.; Högström, E.; Malenfant-Lepage, J.; Morgenstern, A.; Nieuwendam, Alexandre; Oliva, Marc; Paquette, M.; Rudy, A. C. A.; Siewert, M. B.; Sjöberg, Y.; Weege, S.Accelerating climate change and increased economic and environmental interests in permafrost-affected regions have resulted in an acute need for more directed permafrost research. In June 2014, 88 early career researchers convened to identify future priorities for permafrost research. This multidisciplinary forum concluded that five research topics deserve greatest attention: permafrost landscape dynamics, permafrost thermal modeling, integration of traditional knowledge, spatial distribution of ground ice, and engineering issues. These topics underline the need for integrated research across a spectrum of permafrost-related domains and constitute a contribution to the Third International Conference on Arctic Research Planning (ICARP III).