Abstract
The controls that affect the structure and timing of terminations are still poorly understood. We studied a tufa deposit from the Iberian Peninsula that covers Termination II (T-II) and ...whose chronology was synchronized to speleothem records. We used the same chronology to synchronize ocean sediments from the North Atlantic to correlate major climate events in a common timescale. We identify two stages within T-II. The first stage started with the increase of boreal summer integrated solar insolation, and during this stage three millennial climate oscillations were recorded. These oscillations resulted from complex ocean–atmosphere interactions in the Nordic seas, caused by the progressive decay of Northern Hemisphere ice-sheets. The second stage commenced after a glacial outburst that caused the collapse of the Thermohaline Circulation, a massive Heinrich event, and the onset of the Bipolar Seesaw Mechanism (BSM) that eventually permitted the completion of T-II. The pace of the millennial oscillations during the first stage of T-II controlled the onset of the second stage, when the termination became a non-reversible and global phenomenon that accelerated the deglaciation. During the last the two terminations, the BSM was triggered by different detailed climate interactions, which suggests the occurrence of different modes of terminations.
Climate changes in the Iberian Peninsula since the Last Glacial Maximum are associated with distributional shifts of major Mediterranean and European temperate species. The dynamic relationship ...between climate and species in the past may be retrieved from the fossil records available in the Iberian Peninsula. We have used an extensive set of pollen records to reconstruct spatial layers (1 kyr interval) of January minimum temperature, July maximum temperature, and annual precipitation over the time period between 15 and 3 ka. A functional principal component analysis was used to summarise the spatial evolution of climate in areas that share similar climate trends. When compared between them, the identified four areas show different climate trends over the studied period and are coherent with the existence of multiple refugial areas within the Iberian Peninsula.
The site of El Portalón is the entrance to the Cueva Mayor karst system, located in the Sierra de Atapuerca (Burgos, Spain). This is an important Holocene archaeological site, which was excavated in ...the 1970s but from which little has been published. New excavations starting in 2000 have highlighted a deep stratigraphical sequence, with human occupations starting at the end of the Late Pleistocene. In this paper, we present for the first time, on the basis of the small-vertebrate assemblage, palaeoenvironmental and palaeoclimatic reconstructions of the Latest Pleistocene of the Sierra de Atapuerca, well known for its Early to Middle Pleistocene human-bearing localities. The small vertebrates of El Portalón comprise at least 25 species: 4 amphibians (
Alytes obstetricans,
Bufo bufo,
Bufo calamita and
Rana temporaria); 3 squamates (an indeterminate small-size lacertid, an indeterminate large colubrine and
Vipera sp.); 6 insectivores (
Sorex gr.
coronatus-araneus,
Sorex minutus,
Neomys fodiens,
Neomys anomalus,
Talpa europaea and
Galemys pyrenaicus); 2 bats (
Myotis myotis and
Myotis gr.
myotis-blythi); 10 rodents (
Microtus arvalis,
Microtus agrestis,
Microtus oeconomus,
Iberomys cabrerae,
Chionomys nivalis,
Terricola duodecimcostatus,
Arvicola sapidus,
Arvicola terrestris,
Apodemus sylvaticus and
Eliomys quercinus). These taxa, many of which are ecothermal (sensitive to temperature) show variations in their taxonomic diversity throughout the sequence. Although, with the exception of
M. oeconomus, they do not differ from the extant fauna of the Iberian Peninsula, they do so in the abundance of their taxonomic assemblage. When the small vertebrates are grouped and studied in terms of vertical trends through the sequence, it is possible to follow environmental and climatic changes. Results from the small-vertebrate associations indicate that the landscape had open habitats in the vicinity of the Atapuerca caves throughout the sequence, with wet locales in the surrounding area. Woodland and water stream meadows were more developed during “warm” periods (Is5, Is6/Is7 and Is3/Is4), whereas during “cold” periods (H3 and LGM) the environment was slightly more humid in response to winter precipitation and the opening of the landscape. These results are compared with pollen analysis and marine isotopic curves, giving a scenario for the palaeoclimatic and palaeoenvironmental changes that occurred during the Latest Pleistocene in the Sierra de Atapuerca.
Correlations between ecological and cultural changes occurred during a short period between the end of Subboreal and the beginning of Subatlantic in the Amblés Valley (Ávila, central Spain) are ...analyzed, taking into account palaeopalynological and archaeological data. Plant dynamics from pollen analyses, both from archaeological sites and peat bogs, have been interpreted in relation to human settlements and the transformation of economic practices. These provided a comprehensive hypothesis on human/climate interactions at the beginning of the 1st millennium cal BC. There was an ecological crisis in the region that lasted for a century (ca. 850–760
cal BC). This was especially sharp due to both the geographical constraints of the area and its previous agrarian history. This event implied a sudden and abrupt climatic change from xeric and warm conditions (Subboreal) to more humid and cooler ones (Subatlantic). Environmental stress derived from climatic crisis could be an important factor in the explanation of the historical process, whose main consequences were both the origin of the Iron Age peasant villages and the end of the ‘dehesa’ type landscape.
Se presentan los datos de carácter palinológico correspondientes a cinco turberas localizaclas en los sectores central y oriental del Sistema Central Español. Los objetivos de nuestro trabajo es ...poder reconstruir, en base al contenido en polen de dicho material, la evolución de la vegetación en el área y sus implicaciones de carácter paleoclimático. Las dataciones de 14C situan el inicio de esta evolución con anterioridad a los 6.000 años B.P. hasta la actualidad. El factor antrópico es la causa más importante en el desarrollo de la vegetación durante, al menos, los últimos 3.000 años.
A palynological and lithological continuous record from La Mancha Plain (South-central Iberian Peninsula, Spain) is presented. The obtained results have permitted the reconstruction of the climatic ...evolution in the area since the Late-glacial/Holocene transition. The end of the Late-glacial was characterized by a cold and arid climate and it concluded at about 9890±180
yr BP. In the Early Holocene a slight climatic amelioration began, being interrupted by a more arid phase around 8500
yr BP. The Holocene Climatic Optimum started from ca. 8000
yr BP and was characterized by higher temperatures and more humidity. During the Mid-Holocene–Late Holocene times a stage of marked aridity occurred towards 5000
yr BP that preceded the development of a dry mediterranean climate. Under this new climate a short-time arid phase took place around 2500
yr BP after which the mediterranean conditions became accentuated, with an increasing dry climate. This climatic evolution has affected the characteristics of the marshlands of Las Tablas de Daimiel National Park, originating changes in the sedimentary environment. This environment was mainly fluvial until the end of the Holocene Climatic Optimum and became lacustrine–palustrine from the beginning of the more arid conditions.
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