Long-term variability of the Mediterranean Sea surface temperature (1856-2000).

The mean sea surface temperature anomalies (SSTA) of the Mediterranean Sea during the past 150 years (1856-2000) are analysed. The first empirical orthogonal function (EOF) of the covariance matrix of the SSTA explains more than 45% of the variance, suggesting that the temporal variation of the Mediterranean Sea is largely in phase over the whole basin. The mean variability of Mediterranean SSTA from 1856 to 2000 superposes a main irregular oscillation (period of 60-70 years and mean amplitude of 0.4-0.5 degreesC) and a weak long-term positive trend (equivalent to an increase of +0.1 degreesC per century). The last warm phase, which is strongest in the western basin, is not warmer than the decade 1935-1945 or the ending part of the 1960s. The mean temporal evolution of the North Hemisphere is close to the variation of the Mediterranean Sea, except that the long-term increase is more intense in the North Hemisphere. (C) 2003 Academie des sciences. Publie par Editions scientifiques et medicales Elsevier SAS. Tous droits reserves.