Past and Future Drought Variability in the Mediterranean Basin
PROJECT SUMMARY (NSF-Grant ATM-GEO/ATM-Paleoclimate Program 0758486)
Severe midlatitude drought is simulated by state-of-the-art general circulation models (GCMs) as a consequence of anthropogenic climate change. However, the timing, magnitude, and spatial extent of future drought remain poorly constrained, and even observed zonal precipitation trends are not reproduced in model simulations. In the Mediterranean and Near East, meteorological data are sparse and not long enough to effectively capture the potential range of multidecadal to century-scale variability and the spatiotemporal response to radiative forcing. In view of existing uncertainties, longer records of natural hydroclimatology are necessary for assessing the causes of variability and trends in the instrumental record, and evaluating the accuracy of the forced response in forecast GCMs. The PI and co-workers have demonstrated that proxy records developed from tree rings offer a longer-term perspective on episodic drought in this region, and have identified the steps needed to achieve a significant advance in their quality and applicability.
These steps are described by the major objectives of the proposed project, namely:
- Complete development of the tree-ring proxy network necessary for multi-century drought reconstructions of the eastern Mediterranean and Near East (Turkey, Greece, Cyprus, and Lebanon), by geographically and temporally extending and enhancing the existing tree-ring dataset.
- Study patterns of large-scale spatiotemporal climate variations impacting the Middle East via integration of these newly-developed proxy data into spatially-complete gridded climate field reconstructions of drought for the entire Eurasian-Mediterranean Rim, and identify the relationship between regional drought, radiative forcing, and atmosphere-ocean dynamics.
Intellectual Merit:
The reconstruction of past drought variability will provide the long-term perspective necessary to detect and differentiate multidecadal variability and forced climate trends in the region, and will allow the characterization of the preferred timescale, duration, and magnitude of precipitation anomalies in response to radiative forcing and internal climatic variability. Gridded reconstructions permit the identification of the spatial ‘fingerprint’ of radiative forcing on regional patterns of climate variability. The new reconstruction will provide a testing and validation target for GCM simulations of drought in response to both radiative forcing and internal climate system variability, and such models can in turn be used to evaluate hypotheses concerning the causes of drought in the region. The development of gridded precipitation and drought field reconstructions in the eastern Mediterranean adds a critical region to the study of the dynamics of past and future midlatitude drying.
Broader Impacts:
The proposed work will improve and update climate history of the Mediterranean and Near East, and provide a baseline for assessing present and future drought. The oldest and most scientifically valuable forests are being quickly destroyed by population needs, expansion, and land use changes. The PI's excellent working relationships in the region will facilitate making a best use of this rapidly disappearing resource for paleoclimate investigations. Data generated by this work will continue to fill critical gaps in multiple regional and global climate databases valued by programs such as PAGES, CLIVAR, NOAA-OGP, and NASA-EOS. A collaborative meeting and orientation will be held in Tucson after the first field season for the exchange of methodologies, discussion of mutual research objectives, and detailed field planning with colleagues from the study region. University of Arizona undergraduate students will be trained in research methods, participate in fieldwork, and be given an opportunity to present results at professional meetings. Final results from the project will be used to enhance existing university courses.