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Degradation of buried ice and permafrost in the Veleta cirque (Sierra Nevada, Spain) from 2006 to 2013 as a response to recent climate trends
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Orientador(es)
Resumo(s)
The Veleta cirque is located at the foot of the
Veleta peak, one of the highest summits of the Sierra Nevada
National Park (southern Spain). This cirque was the source
of a glacier valley during the Quaternary cold periods. During
the Little Ice Age it sheltered a small glacier, the most
southerly in Europe, about which we have possessed written
records since the 17th century. This glacier still had ice
residues until the mid-20th century. This ice is no longer
visible, but a residue persists along with discontinuous permafrost
trapped under strata of rock blocks that make up an
incipient rock glacier.
From 2006 to 2013, this rock glacier was monitored by
measurement of the temperature of the active layer, the degree
of snow cover on the ground, movements of the body
of the rock glacier and geophysical prospection inside it.
The results show that the relict ice and trapped permafrost
have been steadily declining. The processes that explain this
degradation occur in chain, starting from the external radiation
that affects the ground in summer, which is when
the temperatures are higher. In effect, when this radiation
steadily melts the snow on the ground, the thermal expansive
wave advances into the heart of the active layer, reaching the
ceiling of the frozen mass, which it then degrades and melts.
In this entire linked process, the circulation of meltwaters ful-fils
a highly significant function, as they act as heat transmitters.
The complementary nature of these processes explains
the subsidence and continuous changes in the entire clastic
pack and the melting of the frozen ceiling on which it rests.
This happens in summer in just a few weeks.
All these events, in particular the geomorphological ones,
take place on the Sierra Nevada peaks within certain climate
conditions that are at present unfavourable to the maintenance
of snow on the ground in summer. These conditions
could be related to recent variations in the climate, starting
in the mid-19th century and most markedly since the second
half of the 20th century.
The work and results highlight the climate sensitivity of
the peaks of the Sierra Nevada to the effect of climate change
and its impact on the dynamics of ecosystems, which is a
benchmark for evaluating the current evolution of landscapes
of Mediterranean high mountains.
Descrição
Palavras-chave
buried ice permafrost Sierra Nevada Spain
Contexto Educativo
Citação
Gómez-Ortiz, A., Oliva, M., Salvador-Franch, F., Salvà-Catarineu, M., Palacios, D., de Sanjosé-Blasco, J. J., Tanarro-García, L. M., Galindo-Zaldívar, J., & Sanz de Galdeano, C. (2014). Degradation of buried ice and permafrost in the Veleta cirque (Sierra Nevada, Spain) from 2006 to 2013 as a response to recent climate trends. Solid Earth, 5, 979-993, https://doi.org/10.5194/se-5-979-2014.
Editora
Copernicus Publications