High-resolution patterns of palaeoenvironmental changes during the Little
Ice Age and the Medieval Climate Anomaly in the northwestern
Iberian Peninsula
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Abstract
A high resolution core (9.7 yr cm1) from the Chao de Veiga Mol raised bog (NW Iberian Peninsula) was analyzed
to identify plant macrofossils, estimate peat humification and calculate hydroclimatic indices based on current
bog species, with the overall aim of determining the climate conditions associated with evolution of the bog
during the Medieval Climate Anomaly and the Little Ice Age. These proxies, together with historical and climate
data, proved to be good indicators of the changes in bog surface wetness.
Analysis: of the core led to identification of 9 different periods: two corresponding to the so-called Medieval
Climate Anomaly (930 to 1345 AD, 1075–665 calibrated years before present cal. yr BP); four corresponding to
the Little Ice Age (1345 to 1905 AD; 665–105 cal yr BP); and three corresponding to the last century (1905 to
2000 AD). The findings revealed a generally dry climate that lasted until the 14th century, followed by a transition
to a long period with a more humid, but characteristically very variable climate, which ended at the
beginning of the 20th century and was followed by a rapid transition to more humid conditions and finally, a
change to drier conditions.
The Medieval Climate Anomaly was indicated by the abundance of dry-adapted mosses (Leucobryum glaucum,
Hypnum cupressiforme) and characterized by warm dry conditions and high levels of peat humification, with
alternating wet phases. The LIA period was dated by a large abundance of Sphagnum species (an indicator of
wetness) and a gradual increase in the humification index. However, four different climate phases were differentiated
in this period.
High-resolution reconstruction of the evolution of the CVM bog and the multiproxy approach have together
enabled a more detailed identification of climatic variations in this area, which are generally consistent with the
global models, as well as better definition of the elusive climatic oscillations in the last millennium and confirmation
of the importance of local modulation of global models.
The study provides new information and a detailed chronology of climatic events that will help to refine local
modulation of the climate evolution model in the still quite unexplored region of the NW Iberian Peninsula, a key
area for understanding the paleoclimatic dynamics in SW Europe.
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