SIPCLIP - Temperatura, regime de precipitação e condições do solo no Sudoeste da Península Ibérica num clima mais quente: índices do passado/ Temperature, precitpitation regime and soil conditions in Southwestern Iberian Peninsula under a warmer climate - Insight from the past
Ref.: PTDC/AAC-CLI/100916/2008
Budget (Total/UALG-CIMA): 183.806,00€ / 144.606,00€
Starting date: February 1st., 2010
Ending date: January 31st, 2013
Coordinator: Cristina Veiga-Pires
Domain: Alterações ambientais e climáticas- Alterações climáticas
The documenting of pre-instrumental climate changes is required to better assess the implications of human’s activities on climate and for modelling its future evolution under both natural and anthropogenic forcings.
Moreover, global warming is a challenging topic not anymore at the planet scale but mostly at a regional scale since Global warming seems to induce many different regional scenarios. The present project relies thus on this necessity to provide information on past regional climates to better constrain their complex interactions with global climate. Accordingly, the present project aims to acquire new information to document past climatic conditions in the South-western Iberian Peninsula, based on the analysis of cave speleothems. Speleothems are useful records for paleoclimatic reconstruction because: i) they can be dated through U-Th disequilibrium based techniques reaching ages much older that the ones reached by 14C dating [4,5]; ii) they have visible growth phases and layers enabling to obtain contemporaneous samples and to develop independent chronology [6]; and iii) their chemical origin allows to obtain information on some past climate and environmental conditions such as temperature, precipitation regime and soil conditions based on stable isotope analyses on the carbonated phase (d18O, d13C, D47).
Accordingly, the present project aims to provide, for the first time in Algarve and in Portugal:
i) - a precise chronological control on the timing of major first
order shifts in d18O paleo-precipitation (Objective 1), which can be interpreted as changes in atmospheric circulation patterns as well as changes in ocean vapour sources of d18O;
ii) - soil conditions and changes during a long period of time
based on d13C (Objective 2) that can be associated with switches in the proportions of C3 versus C4 plants existing in the Mediterranean climate of the studied region;
iii) - Carbonate growth temperatures from the stalagmites with the
“clumped isotope” D47 paleothermometer (Objective 3) and therefore to determine the mean annual atmospheric temperature since the Last Interglacial.
However, those three main objectives can only be reached with a good knowledge of the present day cave environments (including their distribution, genesis, physical conditions relative to the above atmospheric conditions, and drip water characteristics) and a very good control on the chronology of the studied stalagmites. The first of these two essential steps will be in charge of the University of Algarve team namely with Geographic Information Systems and Hydrologic surveys together with the Speleologist Association that has the field knowledge and know-how to access the caves. The second of these two essential steps will rely on the combination of U-Th dating, with the expertise existing at the GEOTOP-UQAM-McGill Research Centre, and growth layer image treatment for automatic counting and width measurement with a program developed at CIMA Research Centre. Finally, stable isotope compositions in stalagmites will be obtained at two different laboratories for comparison and calibration purposes, namely at the GEOTOP-UQAM-McGill Research Centre (Canada) and at the Institute of Materials’ Science (Greece). By the end of the project, the team should be able to submit the first Portuguese record of atmospheric conditions (precipitation and temperature) for the last geologic period warmer than the present (Eemian period) to international research group on climate (IGBP, PAGES, PEP, etc..) and contribute thus to a better understanding of Climate Changes.
