Influence of the blended ship log book and station SLP data set on Mediterranean temperature & precipitation back to 1750 June Jürg Luterbacher and collaborators Oeschger Centre for Climate Change Research and Institute of Geography University of Bern, Bern, Switzerland

2 Introduction, why is the Mediterranean of importance? CCA between the blended SLP data and Mediterranean winter climate  main patterns, trends and crossvalidation CCA between the blended SLP data and Mediterranean winter climate  main patterns, trends and crossvalidation Future scenarios Conclusions Outline

3 Case study 2: Circulation dynamics and the influence on the Mediterranean over the last centuries Garcia Herrera et al. 2005; Blending Ship log book data and station pressure Küttel et al. 2008

4 Network, Winter SLP 1817 after Tambora (April 1815) and Verification statistics LL H Very good quality

5 European Winter temperature and SLP anomalies 1817 Luterbacher et al. 2007; Fischer et al. 2007; Küttel et al

6 Tambora (April 1815), produced the “year without a summer 1816” Luterbacher et al. 2007; Fischer et al. 2007; Küttel et al

7 > The area is a ‘Hot-Spot’ for which potential climate change impacts on the environment and other activity sectors are particularly pronounced > Local/regional feedbacks (e.g. soil moisture-precipitation feedback), changes in atmospheric circulation and modes of natural variability are of importance > Importance of hydrological cycle, winter precipitation is crucial  Water resources & water quality  Agriculture & environment  Economics & social development & behaviour Why is the Mediterranean of importance?

8 Importance of winter precipitation compared to the annual rainfall (in %) Xoplaki 2002

9 Data and Methods Independent reconstructions > Gridded temperature , Mediterranean land areas (Luterbacher et al. 2004, Climatic Research Unit) > Gridded precipitation , Mediterranean land areas (Pauling et al. 2006, Climatic Research Unit) > Gridded SLP , combined station pressure and CLIWOC/ICOADS data (Allan and Ansell, 2006; Küttel et al. 2008) Method > Canonical Correlation Analysis (CCA)  selection of optimally correlated patterns between SLP and Mediterranean temperature & precipitation

10 CCA1 (SLP – temperature/precipitation ) dryer and warmer (North), wetter and cooler (South) wetter and cooler (North), drier and warmer (South) + warm & dry cool & wet Xoplaki et al. 2008, work in progress

11 CCA2 (SLP – temperature/precipitation ) dry and warm, pos NAOI wet and cool, neg NAOI warm & dry Xoplaki et al _

12 Mediterranean winter precipitation and temperature trends GISS/NASA Precipitation Temperature Overall drying trendOverall warming trend

13 Cross-validation; importance of SLP to explain Winter precipitation and temperature variability Xoplaki et al Precipitation Temperature Good skill: northern parts and Iberia Good skill: northern and eastern parts

14 Impacts of recent climate change in the Mediterranean (deforestation, desertification, drought, fires …)

15 A1B-Scenario for Winter (with respect to ) Giorgi and Lionello 2008 Sea Level Pressure TemperaturePrecipitation + 2 hPa + 1–2°C - 10–30%

16 Conclusions > New dataset allows dynamical studies on the large scale influence on European climate back to AD 1750 > Crossvalidated results indicate good predictive skill in the north and west (precipitation) and north and east (temperature) > Recent dry and warm winter conditions over the entire Mediterranean are not unique in the context of the past 250 years  Regional differences > Recent trend towards drier and wamer conditions seems to be exceptional > The combined influence of two atmospheric patterns (NAO, East Atlantic / Western Russia) account significantly for the recent drier and warmer trend > Scenarios indicate a trend towards more high pressure situations (similar patterns found through CCA)  drier and warmer winter conditions  Implications on environment, economy and society

17 Thank you very much for your attention!

18 Famous volcanic eruptions; influence on seasonal and continental climate? Agung, 1963 El Chichón, 1982 Krakatau, 1883 Toba, 71,000 BP Pinatubo, 1991 Santorini, 1628 BC Etna, 44 BC St. Helens, 1980 Tropical volcanoes and European climate

19 Network, Winter SLP 1750 and Verification statistics (Reduction of Error, RE) Küttel et al H L H Very good quality

20 Reconstruction Skill Azores Winter Küttel et al. 2008