Emmanuel Garnier

Chapter 1 Mediterranean climate variability over the last centuries: A review

Publisher Summary This chapter discusses a necessary task for assessing to which degree the industrial period is unusual against the background of pre-industrial climate variability. It is the reconstruction and interpretation of temporal and spatial patterns of climate in earlier centuries. There are distinct differences in the temporal resolution among the various proxies. Some of the proxy records are annually or even higher resolved and hence record year-by-year patterns of climate in past centuries. Several of the temperature reconstructions reveal that the late twentieth century warmth is unprecedented at hemispheric scales and is explained by anthropogenic, greenhouse gas (GHG) forcing. The chapter discusses the availability and potential of long, homogenized instrumental data, documentary, and natural proxies to reconstruct aspects of past climate at local- to regional-scales within the larger Mediterranean area, which includes climate extremes and the incidence of natural disasters. The chapter describes the role of external forcing, including natural and anthropogenic influences, and natural, internal variability in the coupled ocean–atmosphere system at subcontinental scale.

An open database of grape harvest dates for climate research: Data description and quality assessment

V. Daux, I. Garcia de Cortazar-Atauri, P. Yiou, I. Chuine, E. Garnier, E. Le Roy Ladurie, O. Mestre, and J. Tardaguila LSCE/IPSL, laboratoire CEA/CNRS/UVSQ, UMR8212, Gif/Yvette, France Université Versailles-Saint Quentin en Yvelines, Versailles, France INRA-Agroclim, Avignon, France CEFE, UMR5175, Montpellier, France CRHQ UMR CNRS Université de Caen, Caen, France Institut Universitaire de France, Paris, France Collège de France, Paris, France Météo-France, Toulouse, France Universidad de la Rioja, Logroño, Spain

Climate reconstructions from grape harvest dates: Methodology and uncertainties

Several studies have used grape harvest date (GHD) as a proxy for temperature variations of the last centuries in Europe. However, the use of grape harvest dates to reconstruct climate is not straightforward, with four possible causes of major flaws. In this study we identify and evaluate the accuracy of GHD as a proxy to past temperature anomalies, uncertainties in the model used to relate temperature to GHD, identity of the grape varieties cultivated in the past, type of wine produced in the past and cultural practices used in the past. Our analyses are based on several phenological and crop models, and on the most complete data set on grape vine phenology and harvest quality. We show that the two methodologies currently used — linear regression models and process-based phenological models — can be accurate, but process-based phenological models ascertain robustness to be applied confidently in different vineyards and different periods. However, we show that several factors can induce a bias in temperature reconstructions using process-based models. We demonstrate the importance of historical information on the studied areas such as the varieties cultivated, the style of wine produced, the quality sought, the agricultural practices, in order to build the most robust model.

The earliest daily barometric pressure readings in Italy: Pisa AD 1657–1658 and Modena AD 1694, and the weather over Europe

The earliest daily barometric pressure readings were taken during the Maunder Minimum of Solar activity (1645—1715). In Italy, observations were made at Pisa over the years 1657—1658 by V. Viviani and A. Borelli, and at Modena during the year 1694 by B. Ramazzini. These readings have been recovered, corrected and adjusted to modern units. The early instruments used and their problems have been thoroughly discussed. Barometer observations recorded by John Locke in Essex (UK) during the year 1694 have also been recovered and corrected. Daily observations were recorded during the same period in Paris by L. Morin; these have previously been published by Legrand and Le Goff (1992: Les observations météorologiques de Louis Morin. Monographie No. 6, Direction de la Météorologie Nationale, Ministère de l’Equipement, de Logement et des Transports, 41 pp.). However, cross-comparisons with the Locke and Ramazzini data have shown that the Paris series needed a further correction to take into account instrumental error. Using these three corrected series, it has been possible to reconstruct the atmospheric circulation over Europe for the year 1694. An indication of the state of the atmospheric circulation can also be made by using the earlier observations recorded in Italy. A common feature of the two periods studied (1657—1658 and 1694) is that winters were characterized by higher pressure compared with the reference period 1961—1990, while the summers generally experienced lower pressure. This latter conclusion indicates that the Azores High was late or not well developed, favouring low temperature and frequent rain in the late spring and early summer.