Terroir climate change


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Terroir climate change

  1. 1. 3 Historic and future climate variability and climate change: effects on vocation, stress and new vine areas Cra viticoltura_libro 1_capitolo 3.indd 1 03/06/10 15:48
  2. 2. Cra viticoltura_libro 1_capitolo 3.indd 2 03/06/10 15:48
  3. 3. CLIMATE, GRAPES, AND WINE: STRUCTURE AND SUITABILITY IN A VARIABLE AND CHANGING CLIMATE G.V. Jones(1) (1) Department of Environmental Studies Southern Oregon University 1250 Siskiyou Blvd Ashland, Oregon Email: gjones@sou.edu ABSTRACT Climate is a pervasive factor in the success of all agricultural systems, influencing whether a crop is suitable to a given region, largely controlling crop production and quality, and ultimately driving economic sustainability. Climate’s influence on agribusiness is never more evident than with viticulture and wine production where climate is arguably the most critical aspect in ripening fruit to optimum characteristics to produce a given wine style. Any assessment of climate for wine production must examine a multitude of factors that operate over many temporal and spatial scales. Namely climate influences must be considered at the macroscale (synoptic climate) to the mesoscale (regional climate) to the toposcale (site climate) to the microscale (vine row and canopy climate). In addition, climate influences come from both broad structural conditions and singular weather events manifested through many temperature, precipitation, and moisture parameters. To understand climate’s role in growing winegrapes and wine production one must consider 1) the weather and climate structure necessary for optimum quality and production characteristics, 2) the climate suitability to different winegrape cultivars, 3) the climate’s variability in wine producing regions, and 4) the influence of climate change on the structure, suitability, and variability of climate. KEYWORD Climate – grapes – wine – temperature – climate change – climate variability INTRODUCTION As a component of terroir, climate arguably exerts the most profound effect on the ability of a region or site to produce quality grapes and therefore wine. Worldwide, the average climatic conditions of wine regions determine to a large degree the grape varieties that can be grown there, while wine production and quality are chiefly influenced by site-specific factors, husbandry decisions, and short-term climate variability (Jones and Hellman, 2003). Historically there have been numerous temperature-based metrics (e.g., heat summation, degree-days, mean temperature of the warmest month, average growing season temperatures, etc.) that have been used for establishing optimum climates for the range of winegrape cultivars (Gladstones, 1992; (Tonietto and Carbonneau, 2004; Jones, 2006). This is not to say that precipitation or any other weather/climate factor is not important, but that temperature is the most influential factor in overall growth and productivity of winegrapes. At the global scale the general bounds on climate 3 - 3 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 3 03/06/10 15:48
  4. 4. suitability for viticulture are found between 12-22°C for the growing season in each hemisphere (Jones, 2007; Fig. 1). As seen in Fig. 1 the 12-22°C climate bounds depict a largely midlatitude suitability for winegrape production, however many sub-tropical to tropical areas at higher elevations also fall within these climate zones. Furthermore, any general depiction of average temperatures will also include large areas that have not been typically associated with winegrape production. This is evident in Fig. 1 where large areas of eastern Europe, western Asia, China, the mid-western and eastern United States, southeastern Argentina, southeastern South Africa, and southern Australia fall within the 12-22°C thresholds. While many of these regions may have the growing season temperatures conducive to growing winegrapes, other limiting factors such as winter minimum temperatures, spring and fall frosts, short growing seasons, and water availability would limit much of the areas mapped to the average conditions. Furthermore, while the vast majority of the world’s wine regions are found within these average growing season climate zones, there are some exceptions. For example, there are defined winegrape growing areas in the United States (Texas, Oklahoma, and the Mississippi delta region), Brazil (São Francisco Valley), and South Africa (Lower Orange River in the Northern Cape) that are warmer than 22°C during their respective growing seasons. However, these regions have different climate risks, have developed viticultural practices to deal with the warmer climates (e.g., two crops per year, irrigation, etc.), or produce table grapes or raisons, and do not necessarily represent the average wine region. Figure 1: Global wine regions, general climate zones, climate variability mechanisms, and their areas of known influences as described in the text. The wine regions are derived from governmentally defined boundaries (e.g., American Viticultural Areas in the United States, Geographic Indicators in Australia and Brazil, and Wine of Origin Wards in South Africa) or areas under winegrape cultivation identified with remote sensing (e.g., Corine Land Cover for Europe) or aerial imagery (e.g., Canada, Chile, Argentina, and New Zealand). The general climate zones are given by the 12-22°C growing season (Apr-Oct in the Northern Hemisphere and Oct-Apr in the Southern Hemisphere) average temperatures derived from the WorldClim database (Hijmans et al. 2005). ENSO – El Niño Southern Oscillation, PDO – Pacific Decadal Oscillation, NAO – North Atlantic Oscillation, IOD – Indian Ocean Dipole, AO – Arctic Oscillation, AAO – Antarctic Oscillation, SST – Sea Surface Temperatures. 3 - 4 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 4 03/06/10 15:48
  5. 5. Further refining the climate suitability for many of the world’s most recognizable cultivars, Jones (2006) shows that high quality wine production is more realistically limited to 13-21°C average growing season temperatures (Fig. 2). The climate-maturity zoning in Fig. 2 was developed based upon both climate and plant growth for many cultivars grown in cool to hot regions throughout the world’s benchmark areas for those winegrapes. While many of these cultivars are grown and produce wines outside of the bounds depicted in Fig. 2, these are more bulk wine (high yielding) for the lower end market and do not typically attain the typicity or quality for those same cultivars in their ideal climate. Furthermore, growing season average temperatures below 13°C are typically limited to hybrids or very early ripening cultivars that do not necessarily have large-scale commercial appeal. At the upper limits of climate, some production can also be found with growing season average temperatures greater than 21°C, although it is mostly limited to fortified wines, table grapes and raisons (up to 24°C). Figure 2: Climate-maturity groupings based on relationships between phenological requirements and growing season average temperatures for high to premium quality wine production in the world's benchmark regions for many of the world’s most common cultivars. The dashed line at the end of the bars indicates that some adjustments may occur as more data become available, but changes of more than +/- 0.2-0.5°C are highly unlikely (Jones, 2006). An example of cool climate suitability is found with the widely recognized Pinot Noir variety, which is typically grown in regions that span from cool to lower intermediate climates with growing seasons that range from roughly 14.0-16.0°C (e.g., Burgundy or Northern Oregon). The coolest of these is the Tamar Valley of Tasmania, while the warmest is the Russian River Valley of California. Across this 2°C climate niche, Pinot Noir produces the broad style for which is it known with the cooler zones producing lighter, elegant wines and the warmer zones producing more full-bodied, fruit-driven wines. While Pinot Noir can be grown outside the 14.0-16.0°C 3 - 5 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 5 03/06/10 15:48
  6. 6. growing season average temperature bounds it typically is unripe or overripe and readily loses its typicity. As examples of intermediate to warmer climate cultivars, the noble winegrapes Cabernet Franc and Cabernet Sauvignon, are clearly two of the most widely recognized in the world. The spread of these two cultivars worldwide has produced an assortment of wine styles from quite diverse regions. Fig. 2 shows this wide diversity with both Cabernet Franc and Cabernet Sauvignon having roughly 3.5°C climate ranges, nearly double that of Pinot Noir. Cabernet Franc can be grown in intermediate to warm climates (15.4-19.8°C) as evidenced by its quality production in the Loire Valley of France. Cabernet Sauvignon on the other hand is grown in regions that span from intermediate to hot climates with growing seasons that range from roughly 16.8-20.2°C (e.g., Bordeaux or Napa). The lower climate limit for Cabernet Sauvignon suitability is found in Hawke’s Bay, New Zealand while the upper climate limit is found in Robertson, South Africa. While the average climate structure in a region determines the broad suitability of winegrape cultivars, climate variability influences issues of production and quality risk associated with how equitable the climate is vintage to vintage. Climate variability in wine regions influences grape and wine production through cold temperature extremes during the winter in some regions, frost frequency and severity during the spring and fall, high temperature events during the summer, extreme rain or hail events, and broad spatial and temporal drought conditions. Climate variability mechanisms that influence wine regions are tied to large scale atmospheric and oceanic interactions that operate at different spatial and temporal scales. The most prominent of these is the large scale Pacific sector El Niño-Southern Oscillation (ENSO), which has broad influences on wine region climates in North America, Australia and New Zealand, South Africa, South America, and Europe (Jones, 2010; Fig. 1). While each of the known climate variability mechanisms reveals some temporal periodicity, increases in climate variability for many wine regions have been observed. Increases in climate variability in a given region would bring about greater risk associated with climate extremes, which in turn would strain the economic viability of wine production in any region. Both observations and models indicate that climates experience changes in both the mean and the variability of temperatures in wine regions and elsewhere (Jones, 2007). For example, if the change response of a warming climate was only in the mean, then there would be less cold weather and more hot and record hot weather. On the other hand, increases in the temperature variance alone would result in more cold and hot weather and record conditions. However, evidence points to increases in both the mean and variance which would bring about less change for cold weather events and much more hot weather and record hot weather (IPCC, 2007). For example, Schär et al. (2004) demonstrate that the European summer climate might experience a pronounced increase in year-to-year variability in response to greenhouse-gas forcing. Such an increase in variability might be able to explain the unusual European summer 2003, and would strongly affect the incidence of heat waves and droughts in the future. Evidence of changing climate variability in wine regions was also found by Jones (2005) and Jones et al. (2005a) where the coefficient of variability in the growing season climates throughout the western US and many other wine regions globally has increased over the last 50 years. Jones et al. (2005a) also found that model projections through to 2050 show a continued increase in the coefficient of variability in 20 of 27 wine regions globally. From the discussion above on the climate structure, suitability, and variability associated with regional to global wine production it is clear that viticultural regions are located in relatively 3 - 6 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 6 03/06/10 15:48
  7. 7. narrow geographical and climatic ranges. In addition, winegrapes have relatively large cultivar differences in climate suitability further limiting some winegrapes to even smaller areas that are appropriate for their cultivation. These narrow niches for optimum quality and production put the cultivation of winegrapes at greater risk from both short-term climate variability and long-term climate changes than more other more broad acre crops (Jones, 2007). At the global scale, trends in wine region climates have resulted in warmer growing season climates that have allowed many regions to produce better wine, while future climate projections indicate more benefits for some regions and challenges for others. The observed growing season warming rates for numerous wine regions across the globe during 1950-2000 averaged 1.3°C (Jones et al. 2005a), with the warming driven mostly by changes in minimum temperatures, with greater heat accumulation, a decline in frost frequency that is most significant in the dormant period and spring, earlier last spring frosts, later first fall frosts, and longer frost-free periods (Jones, 2005). However, climate model projections by 2050 for the same wine regions predict growing season warming of an additional 1.5-2.5°F on average with spatial analyses showing the potential for relatively large latitudinal shifts in viable viticulture zones with increasing area on the poleward fringe in the Northern Hemisphere (NH) and decreasing area in the Southern Hemisphere (SH) due to the lack of land mass (Jones, 2007). Within regions, spatial shifts are projected to be toward the coast, up in elevation, and to the north (NH) or south (SH). Furthermore, climate variability analyses have shown evidence of increased frequency of extreme events in many regions, while climate models predict a continued increase in variability globally. In addition, phenological changes observed over the last 50 years for numerous locations and varieties globally indicate that grapevines have responded to the observed warming with earlier events (bud break, bloom, véraison, and harvest) and shorter intervals between events that range from 6-17 days depending on variety and location (Jones et al. 2005b). To place viticulture and wine production in the context of climate suitability and the potential impacts from climate change, Fig. 2 provides the framework for examining today’s climate- maturity ripening potential for premium quality wine varieties grown in cool, intermediate, warm, and hot climates (Jones, 2006). From the general bounds that cool to hot climate suitability places on high quality wine production, it is clear that the impacts of climate change are not likely to be uniform across all varieties and regions, but are more likely to be related to climatic thresholds whereby any continued warming would push a region outside the ability to produce quality wine with existing varieties. For example, if a region has an average growing season temperature of 15°C and the climate warms by 1°C, then that region is climatically more conducive to ripening some varieties, while potentially less for others. If the magnitude of the warming is 2°C or larger, then a region may potentially shift into another climate maturity type (e.g., from intermediate to warm). While the range of potential varieties that a region can ripen will expand in many cases, if a region is a hot climate maturity type and warms beyond what is considered viable, then grape growing becomes challenging and maybe even impossible. CONCLUSIONS Overall, winegrapes are a climatically sensitive crop whereby quality production is achieved across a fairly narrow geographic range. In addition, winegrapes are grown largely in mid-latitude regions that are prone to high climatic variability that drive relatively large vintage differences in quality and productivity. However, while understanding the climate structure and variability in 3 - 7 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 7 03/06/10 15:48
  8. 8. wine regions worldwide provides more exacting varietal selections and vintage to vintage production management, the projected rate and magnitude of future climate change will likely bring about numerous potential impacts for the wine industry, including – added pressure on increasingly scarce water supplies, additional changes in grapevine phenological timing, further disruption or alteration of balanced composition in grapes and wine, regionally-specific needs to change the types of varieties grown, necessary shifts in regional wine styles, and spatial changes in viable grape growing regions. While uncertainty exists in the exact rate and magnitude of climate change in the future, it would be advantageous for the wine industry to be proactive in assessing the impacts, invest in appropriate plant breeding and genetic research, be ready to adopt suitable adaptation strategies, be willing to alter varieties and management practices or controls, or mitigate wine quality differences by developing new technologies. BIBLIOGRAPHY Gladstones, J., 1992. Viticulture and Environment: Winetitles, Adelaide, Australia. 310 pp. Hijmans, R. J., S. E. Cameron, J. L. Parra, P. G. Jones and A. Jarvis. 2005. Very high resolution interpolated climate surfaces for global land areas. International Journal of Climatology 25: 1965-1978. IPCC 2007. Alley R. et al. Climate Change 2007: The Physical Science Basis. Summary for Policymakers. Contribution of the Working Group I to the Fourth Assessment of the Intergovernmental Panel on Climate Change. IPCC Secretariat (http://www.ipcc.ch/). Jones, G.V. and E. Hellman. 2003. Site Assessment: in “Oregon Viticulture” Hellman, E. (ed.), 5th Edition, Oregon State University Press, Corvallis, Oregon, p 44-50. Jones, G.V., 2005. Climate change in the western United States grape growing regions. Acta Horticulturae (ISHS), 689:41-60. Jones, G.V., M.A. White, O.R. Cooper, and K. Storchmann. 2005a. Climate Change and Global Wine Quality. Climatic Change, 73(3): 319-343. Jones, G.V., E. Duchêne, D. Tomasi, J. Yuste, O. Braslavksa, H. Schultz, C. Martinez, S. Boso, F. Langellier, C. Perruchot, and G. Guimberteau. 2005b. Changes in European Winegrape Phenology and Relationships with Climate, GESCO Proceedings, August 2005. Jones, G.V. 2006. Climate and Terroir: Impacts of Climate Variability and Change on Wine. In Fine Wine and Terroir - The Geoscience Perspective. Macqueen, R. W., and L. D. Meinert, (eds.), Geoscience Canada Reprint Series Number 9, Geological Association of Canada, St. John's, Newfoundland, 247 pages. Jones, G.V. 2007. Climate Change and the global wine industry. Proceedings from the 13th Australian Wine Industry Technical Conference, Adelaide, Australia. Jones, G.V., Ried, R., and A. Vilks 2010. A Climate for Wine. In “The Geography of Wine”, edited by P. Dougherty. Springer Press, (in press). Schär, C., P.L. Vidale, D. Lüthi, C. Frei, C. Häberli, M.A. Liniger, and C. Appenzeller. 2004. The role of increasing temperature variability for European summer heat waves. Nature, 427, 332- 336. Tonietto, J. and A. Carbonneau. 2004. A multicriteria climatic classification system for grape- growing regions worldwide. Agric. Forest Meteorol. 124, 81-97. 3 - 8 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 8 03/06/10 15:48
  9. 9. THE IMPACT OF GLOBAL WARMING ON ONTARIO’S ICEWINE INDUSTRY D.Cyr(1) and T.B. Shaw(2) (1) Department of Finance, Operations and Information Systems & Cool Climate Oenology and Viticulture Institute, Brock University St. Catharines Ontario, Canada, L2S 3A1 dcyr@brocku.ca (2) Department of Geography &Cool Climate Oenology and Viticulture Institute Brock University, St. Catharines Ontario, Canada, L2S 3A1 Corresponding author: tshaw@brocku.ca 905-688-5550, Ext. 3866 ABSTRACT Ontario’s wine regions lie at the climatic margins of commercial viticulture owing to their cold winters and short cool growing season. The gradual warming of northern latitudes projected under a human-induced climate change scenario could bring mixed benefits to these wine regions. On the one hand, climate change could moderate the severity of winter temperatures and extend the growing season and on the other, it could be jeopardize the production of internationally renowned icewines for which Canada is famous. This paper examines the trends in winter temperatures over the last forty years for the Niagara Peninsula wine region in Ontario. The study analyzes the occurrences of temperatures ≤ -8o C in the months of November, December, January and February in which the frozen grapes are normally picked. The results of trend analysis showed a high degree of variability along with a weak declining trend in the number of picking days. Two major risks to icewine grapes are prolonged warm and wet conditions that could lead to rot and secondly, destruction of the crop by bird predators. The study also discussed the potential use of weather contracts to mitigate these risks. Key Words: climate change, Ontario, icewine, impacts, weather contracts INTRODUCTION Ontario’s main wine regions comprise the Niagara Peninsula and the adjacent regions of Lake Erie Northshore, Pelee Island and Prince Edward County. Although the Great Lakes moderate their climates throughout the year, these areas are often incorrectly perceived as being on the climatic limits of successful commercial viticulture, owing to their snowy winters and short cool growing seasons. Endowed with a favourable range of mesoclimates, topographies and soils, wine production has evolved slowly under a scrupulous system of site selection matched by suitable cold-tolerant international grape varieties. Still and sparkling wines of quality and distinction are produced in a wide range of styles mainly for the Canadian market. However, it is the icewine that uniquely combines the regions’ climatic, viticulture and oenological attributes that first brought international recognition to the Canadian wine industry. Although cold winters are the norm for this semi-continental climate, global warming could threaten the stability of icewine production. On one hand, these regions are likely to benefit from a warmer climate that could extend the growing season and moderate the severity of winter temperatures. On the other, the production of the internationally renowned icewines could be jeopardized by unpredictably warmer spells 3 - 9 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 9 03/06/10 15:48
  10. 10. 2 during the first half of winter, when frozen grapes are typically harvested, after having experienced a number of freeze-thaw cycles. Climate Change and Viticulture The Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report in 2007 stated that there has been anthropogenic warming over the last 50 years averaged over each continent. The temperature increase is widespread over the globe, but is greater at higher northern latitudes. Average Arctic temperatures have increased at almost twice the global average rate in the past 100 years. Observed decreases in snow and ice extent are also consistent with warming. All of North America is projected to warm during this century, and the annual mean warming is likely to exceed the global mean warming in most areas. In northern regions, warming is likely to be largest in winter. It is very likely that cold days, cold nights and frosts could become less frequent over most land areas, while hot days and hot nights could become more frequent. Also predicted are is a very likely decrease in snow season length and snow depth in most of Europe and North America. (IPCC, 2007). There exits now several studies that have analyzed the impacts of climate change and variability on viticulture (Kenny and Harrison, 1992; Stock et al., 2004; Jones and Goodrich, 2008), while others have examined temperatures trends (including the growing season average, maximum and minimum temperatures) the climatic characteristics of particular wine regions, grapevine phenology, grape composition and yield, and the resulting wine quality (Jones and Davis, 2000; Bindi et al.,1996). Several studies have projected a continued warming trend in the growing season, more frequent extreme temperatures, early budburst and an increase in the frost-free- period (Easterling et. al., 2000; Kramer, 1994; Duchene and Schneider, 2004). In Canada, most northern agricultural regions are expected to experience warmer conditions, longer frost-free seasons and increased evapotranspiration. The national average temperature for the winter 2009/2010 was 4.0°C above normal, based on preliminary data, which makes this the warmest winter on record since nationwide records began in 1948. The previous record was 2005/2006 which was 3.9°C above normal. The climate is gradually becoming wetter and warmer in southern Canada throughout the twentieth century and in all of Canada during the latter half of the century. In southern Canada, spring temperatures have increased, greatly shortening the period of freezing temperatures suitable for snowfall while daily minimum temperatures, indicators of night-time temperatures, have increased significantly over the past century (Zhang et.al, 2002). The severity of winters has determined the distribution of perennial fruit and vine crops, but warmer winters are not altogether beneficial. Winter damage could actually increase in eastern Canada, due to reduced cold hardening during the fall, an increase in the frequency of winter freeze-thaw events, and a decrease in protective snow cover. Conversely, vine and orchard crops are expected to benefit from a decreased risk of winter damage. However, milder winter temperatures would reduce cold stress, while a decrease in late spring frosts would lower the risk of bud damage in many regions. Nonetheless, an increase in winter free-thaw events would decrease the hardiness of the trees, and increase their sensitivity to cold temperatures in late winter (Natural Resources Canada, 2002). Also damaging to perennial crops are temperature fluctuations within the winter season (repeated freeze-thaw cycles) and the annual variability that are characteristic of the climate of the Great Lake Region. Fig. 1 shows winter departures from the normal temperature with an increasing but highly fluctuating trend. 3 - 10 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 10 03/06/10 15:48
  11. 11. 3 Winter Departures and Long-Term Trends for the Great Lakes Region 1948-2010 -3 -2 -1 0 1 2 3 4 5 1948 1950 1952 1954 1956 1958 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Year DegreeC Figure. 1: Winter departures and long term trends in the Great Lakes region 1948 - 2010 Icewine The first icewine (Eiswein) is believed to have been made in Germany around 1794 in Franconia with the advent of early freezing temperatures before the grape crop could be harvested. Nonetheless, winemakers harvested and pressed the frozen grapes and fermented the juice to produce a sweet wine. Germany continued to produce icewine in an unregulated fashion until 1982 when it was formally granted its own quality category in the German Wine Law. Unlike the Canadian winters, the already moderate European winters now becoming increasingly warmer with climate change make icewine production in Germany and Austria highly risky. In Ontario, icewines are made principally from the Vidal, Riesling, Cabernet Franc and Gewürztraminer grapes that must harvested in a frozen state at temperatures ≤ -8o C after November 15. The temperatures at picking time are limited from -8o C to -14o C, which also determines the maximum and minimum amount of juice that can be extracted. The optimum harvesting temperature is between -10o and -12o C. The ideal parameters for the pressed juice are between 38o and 42o Brix, between 120 and 150 L per ton according to the variety, titratable acidity of 10-12 g/l tartaric acid and pH between 3.1 and 3.3 (Ziraldo and Kaiser, 2007). According to the Vintners Quality Alliance Ontario (VQA), the finished wine must have a Brix of 35o or more, residual sugar of 125 g/l and a minimum alcohol content of 7 percent but not exceeding 14.9 percent by volume. Riesling and Vidal icewines exhibit typically rich aromas and flavours that are characteristic of ripe tropical fruits such as lychee, papaya and pineapple. The sweet but firm acidity of icewines, attributed to malic acid dominance, make them perfectly balanced. This paper examines the trends in winter temperatures over the last forty years for the Niagara Peninsula Wine Region of Ontario that is also Canada’s major producer of 3 - 11 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 11 03/06/10 15:48
  12. 12. 4 icewines. The study analyzes the occurrences of temperatures ≤ -8o C in the months of November, December, January and February in which the frozen grapes are normally picked. Even though the grapes may be partially frozen on several occasions at higher minimum temperatures, the temperature at harvest must fall to -8o C in order to be certified as icewine according to the Vintners Quality Alliance (VQA) standards. The ideal conditions should include dry and moderately cold conditions over a two week period with partial freezing, followed by a real freeze with daytime temperatures between -10o C to - 12o C in the months of December and January. DATA AND METHODS To achieve the above objectives, the study examined daily climatic data for a representative climatic station located at Vineland in the Niagara Peninsula wine region of Ontario. This climatic station has a long history of reliable data going back to the 1880s and is located in an area that has remained essentially rural. This study utilized data for the 1977 to 2008 period retrieved from the Environment Canada’s Online Climate Database. Data from this official source typically undergo rigorous quality checks before being released for public use. This period of analysis contains no missing records. The study examined the daily minimum temperatures for the months of December, January and February and the latter half of November. It included any day with minimum temperature ≤ -8o C, the legally recognized lower threshold temperature that ensures that the grape is fully frozen on the vine for icewine. The analysis of the occurrences of days with the threshold minimum temperatures for harvesting icewine grapes does not account for the length of the freeze event. For example, an event with ≤ -8o C could have lasted under an hour while another event could have lasted for several hours. Records of hourly values suitable for icewine only began about fifteen years ago for the Niagara Peninsula wine region and less than ten years for the Lake Erie North Shore. In absence of long-term hourly values and for the purpose of this study, we defined an icewine event as one in which there were two consecutive days with minimum temperatures ≤ -8o C. To determine any evidence of long-term trend and variability in the data, we analyzed the time series using simple linear regression. We analyzed the total number of events for individual months and the combined total for each winter season. RESULTS AND DISCUSSION Optimal Harvesting Period November 15 marks the start of the official harvesting date of grapes for icewines. However, the record over the last forty years showed a total of twelve days experienced minimum temperatures ≤ -8o C. Only one year (1989) had four consecutive days with ≤ -8o C that were suitable for harvesting frozen grapes. An early harvest date means higher yields, since loss to predators, a longer hanging time and spoilage due to warmer temperatures can reduce yields and quality. Fig. 2 and 3 show the most suitable period for harvesting frozen grapes. It begins roughly from the beginning of the second week in January and extends to approximately the middle of February. This period has a slightly >50% chance of the occurrence of freezing temperatures ≤ -8o C. 3 - 12 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 12 03/06/10 15:48
  13. 13. 5 Figure 2. Average daily minimum temperatures for December to February for the period 1970-2007 Figure 3. Probability of daily minimum temperatures ≤ -8o C for the period 1970-2007 Trends in Freezing Temperatures Some winegrowers will harvest at -8o C, while others may await lower temperatures over a longer. An analysis of the frequency of days (Fig. 4) with freezing temperatures ≤ -8o C for the December to February period shows a high degree of inter-annual variability with a weak declining trend for the 1970-2007 period. Values range from a high of 50 in 1978 to a low of 11 in 2002 duration. 3 - 13 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 13 03/06/10 15:48
  14. 14. 6 Figure 4. Frequency of days with ≤ -8o C between December and February for the 1970-2007 period Trends in Icewine Events We defined an icewine event as one with at least two consecutive days with ≤ -8o C. Trend analysis in Fig. 5 shows high inter-annual variability along with a declining trend for the three coldest months. The sharpest decline is observed in February followed by January and December, respectively. Figure 5. Temporal distribution of icewine events (picking days) for the months of December, January and February for the 1970-2007 period 3 - 14 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 14 03/06/10 15:48
  15. 15. 7 MANAGING THE RISKS OF GLOBAL WARMING In addition to the declining trend observed in the number of picking days, Fig. 5 also appears to provide some indication of increased inter-year volatility, particularly in the months of January and February, from 1990 onward. This is consistent with the results of Cyr and Kusy (2007) who, in a study of estimated annual hours of icewine harvesting time, find some evidence of increased volatility from the early 1990’s onward. Although adaptation strategies in terms of viticulture, to mitigate crop loss due to the impact of increasingly warm and wet conditions may be developed, the increased volatility can create uncertainty in terms of the year-to-year expenditures associated with such methods. Cyr and Kusy (2007) considered the potential use of weather contracts for hedging such economic risks, particularly with respect to icewine harvesting. Although weather derivative contracts first began trading in the mid 1990s the availability of such contracts for hedging specialized weather risks has only developed substantially in recent years. This growth is partly due to the increased awareness of the risks resulting from global warming and the potential role of weather contracts in mitigating some of them (Chicago Mercantile Exchange, 2009). Many issues still remain problematic in terms of the use of weather contracts however, including the identification of appropriate statistically models for estimating future weather variability as well as other issues critical to the pricing of such contracts. In addition the practical application of such contracts requires an assessment of the correlation of specific weather events faced by a producer to those associated with a nearby weather station employed as the basis of the contracts. CONCLUSIONS Like many agricultural sectors, the viticulture industry is highly sensitive to the weather. Major risks at the production level are attributed to occurrences of extreme events and random variability in key weather variables. The study analyzes the occurrences of temperatures ≤ -8o C in the months of November, December, January and February in which the frozen grapes are normally picked. The results of trend analysis showed a high degree of inter-annual variability along with a weak declining trend over the last forty years in the number of days suitable for harvesting the frozen grape. Two major risks to icewine grapes are firstly, prolonged warm and wet conditions that could lead to rot and secondly, the destruction of the crop by bird predators. In the short-term, producers can hedge their risks by buying weather contracts, while modelling long-term changes in the regional climate could help to determine appropriate adaptive strategies. References BINDI, M., FIBBI, L., GOZZINI, B., ORLANDINI, S., AND MIGLIETTA, F. Modelling the impact of future climate change scenarios on yield and yield variability of grapevine, Climate Research, 7, 213-224. BRKLACICH, M., BRYANT, C., VEENHOF, B AND BEAUCHESNE, A. (1998): Implications of global climatic change for Canadian agriculture: a review and appraisal of research from 1984 to 1997; in Responding to Global Climate Change: National Sectoral Issue, (ed.) G. Koshida and W. Avis, Environment Canada, Canada Country Study: Climate Impacts and Adaptation, v. VII, p. 219-256. 3 - 15 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 15 03/06/10 15:48
  16. 16. 8 CHICAGO MERCANTILE EXCHANGE GROUP/STORM EXCHANGE. 2009. Best Practices for the Agricultural Community (Webniar Series). Accessed on September 19th 2009 at http://www.cmegroup.com/education/events/forms/storm_webinar_series.html. CYR, D. AND KUSY, M. 2007. Canadian Icewine production: A case for the use of weather derivatives, Journal of Wine Economics, 2, 1-23 DUCHENE, E and SCHNEIDER, C. 2005. Grapevine and climatic changes: a glance at the situation on Alsace, Agronomy and Sustainable Development, 25, 93-99. EASTERLING D.R. et. al. 2000. Observed variability and trends in extreme climate events: A brief review, Bulletin of American Meteorological Society, 81, 417-425. INTERNATIONAL PANEL ON CLIMATE CHANGE (IPCC) 2007. IPCC Fourth Assessment Report. http://www.ipcc.ch HAEBERLI, W., FRAUENFELDER, R. , KAAB, A and WAGNER, S .2004. Characteristics and potential climatic significance of miniature ice caps, Journal of Glaciology, 50 (168) 129-136. JONES, G.V. and DAVIS, R.E. 2000. Climate influences on grapevine phenology , grape composition, and wine quality for Bordeaux, France, American Journal of Enology and Viticulture, 51, 249-261 JONES, G.V. and GOODRICH, G.B. 2008. Influence of climate variabilityon wine regions in the Western United States and on wine quality in the Napa Valley, Climate Research, 35, 241-254. KENNY, G.J. and HARRISON, P.A. 1992. The effects of climate variability and change on grape suitability in Europe, Journal of Wine Research, 3, 163-183. KRAMER, K. 1994. A modelling analysis of the effects of climatic warming on the probability of spring frost damage to tree species in the Netherlands and Germany, Plant , Cell and Environment, 17, 367-377. NATURAL RESOURCES CANADA. 2002. Climate Change Impacts and Adaptation: A Canadian Perspective : Impacts on Agriculture, Ottawa, Ontario. STOCK, M., GERSTENGARBE, F., KARTSCHALL, T. and WERNER, P. 2004. Reliability of Climate Change Impact Assessments for ViticultureInternational Scoiety for Horticulture Science, 68 (9). ZHANG, X., VINCENT, L.A, HOGG, W.D. NIITSOO, A. 2002. Temperature and precipitation trends in Canada during the 20th century, Atmosphere-Ocean, 38, 395-429. VINTNERS QUALITY ALLIANCE ONTARIO: www.vqaontario.com ZIRALDO, D and KAISER, K. 2007. Ice Wine: Extreme Wine Making, Key Porter Books Limited, Toronto, Ontario. 3 - 16 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 16 03/06/10 15:48
  17. 17. L’EFFET DU CLIMAT VITICOLE SUR LA TYPICITÉ DES VINS ROUGES Caractérisation au Niveau des Régions Viticoles Ibéro-Americaines J. Tonietto(1) , V. Sotés(2) , M.C. Zanus(1) , C. Montes(3) ,E.M. Uliarte(4) , L. Antelo(5) , P. Clímaco(6) A. Peña(7) , C.C. Guerra(1) , C.D. Catania(4) , E. Kohlberg(8) , G. E. Pereira(1) , J.R. da Silva(9) , J.V. Ragoût(10) , L.V. Navarro(10) , O. Laureano(9) , R. de Castro(9) , R.F. del Monte(4) , S.A. del Monte(4) , V.D. Gómez-Miguel(2) , A.Carbonneau(11) . (1) EMBRAPA Uva e Vinho, Rua Livramento, 515 - 95700-000 - Bento Gonçalves, Brésil, tonietto@cnpuv.embrapa.br ;(2) UPM - Universidad Politécnica de Madri, Espagne ; (3) CEAZA - Centro de Estudios Avanzados en Zonas Áridas, Chili ; (4) INTA - EEA Mendoza, Argentine ;(5) PFCUVS-FAUTAPO, Desarrollo de Mercados, Bolivie ; (6) INIA/INRB, Estação Vitivinícola Nacional, Portugal ;(7) Universidad de Chile ; (8) Expert Oenologue, Bolivie ; (9) ISA-UTL - Instituto Superior de Agronomia, Portugal ; (10) Expert Oenologue, Espagne ; (11) AGRO Montpellier, France. RÉSUMÉ Il n’existe presque pas d’études qui caractérisent l’effet du climat viticole sur la typicité des vins en considérant les différents types de climats à l’échelle mondiale. Cette étude fait partie d’un projet CYTED de zonage vitivinicole. L’objectif a été de caractériser l’effet du climat viticole sur la typicité des vins sur une macro région viticole du monde. La méthodologie a été appliquée à un ensemble de 45 régions viticoles situées sur 6 pays Ibéro-Américains : Argentine, Bolivie, Brésil, Chili, Espagne et Portugal. Le climat viticole de chaque région viticole a été caractérisé para les 3 indices climatiques viticoles du Système CCM Géoviticole : IH (Indice Héliothermique de Huglin), (IF) Indice de Fraîcheur des Nuits) et IS (Indice de Sécheresse). Les principales caractéristiques sensorielles observées de façon fréquente sur des vins rouges représentatifs élaborés avec des raisins-de-cuve de chacune des ces 45 régions viticoles ont été décrites pour des œnologues de chaque pays, an utilisant la méthodologie proposée par Zanus & Tonietto (2007). L’évaluation sensorielle réalisée concerne l’intensité de perception de la Couleur (Cou), de l’Arôme Total (Ar), de l’Arôme – fruit mûr (Ar-Fm), de la Concentration (Con), de l’Alcool (Al), des Tanins (Tan), de l’Acidité (Ac) et la Longueur en bouche (Lon). Les données ont été soumises à l’analyse des corrélations pour l’ensemble des variables et à l’ACP. L’étude indique qu’une partie de la typicité des vins est déterminée par le climat viticole des régions et que les indices du Système CCM Géoviticole sont pertinents pour relier aux caractéristiques sensorielles des vins. Le déterminisme de l’IH, de l’IS et de l’IF à été mis en évidence. MOTS CLÉS : climat viticole, indice climatique, Système CCM, vin, typicité. ABSTRACT THE EFFECT OF VITICULTURAL CLIMATE ON RED WINE TYPICITY A Characterization on Iberoamerican Grape-Growing Wine Regions There are many studies in the world that characterize the effect of the climate on grape composition and wine typicity concerning particular viticultural regions and climates. However, there are not studies, in a worldwide scale, that characterize this effect considering different climate types. This study is part of a CYTED project in vitivinicultural zoning. The objective was to characterize the effect of viticultural climate on the wine typicity on a macro viticultural region of the world. The methodology employed in this investigation used 45 grape-growing regions in 6 Iberoamerican countries: Argentina, Bolivia, Brazil, Chile, Portugal and Spain. The viticultural climate of each region was characterized by the 3 13 - 17 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 17 03/06/10 15:48
  18. 18. viticultural climate index of the Géoviticulture MCC System (Tonietto & Carbonneau, 2004): HI (Heliothermal index), CI (Cool night index) and DI (Dryness index). The main sensory characteristics observed frequently in representative red wines produced with grapes of each of these 45 grape-growing regions were described by enologists in the respective countries, using the methodology of Zanus & Tonietto (2008). The sensory evaluation concerned to the intensity of perception of Color (Cou), Total Aroma (Ar), Aroma - ripe fruit (Ar-Rf), Body – palate concentration (Con), Alcohol (Al), Tannins (Tan) and Acidity (Ac). The Persistence in mouth (Lon) was also evaluated. The data were submitted to a correlation matrix for the variables and to a Principal Component Analysis (PCA). The results showed significant correlation effect for: HI – positive with Al and negative with Ac; DI – positive with Ac and negative with Al and Ar-Rf; CI – negative with Cou, Tan, Lon, Ar and Con. The results confirm the effect of the temperatures on increasing alcohol and reducing acidity perception of red wines. The soil water availability shows that higher values of DI contributes to rise the acidity perception and to diminish alcohol and aroma (ripe fruit) perception. The effect of nycto-temperatures during ripening was confirmed influencing several sensory characteristics of the wines: the cooler the night temperatures during maturation (lower CI values) the higher is the perception of color, aroma, palate concentration, tannins and the persistence in mouth. Part of the wine typicity of the regions was determined by the viticultural climate. Others are related with varieties, viticultural and wine making processes, among others in each region. KEYWORDS : viticultural climate, climatic index, MCC System, wine, typicity. INTRODUCTION Il existe plusieurs études dans le monde qui caractérisent l’effet du climat sur la composition physique et chimique du raisin-de-cuve et sur la typicité des vins dans des régions et climats viticoles particuliers. Mais il n’existent pas d’études à l’échelle mondiale qui caractérisent cet effet en considérant les différents types de climats mondiaux. Cette étude fait partie d’un projet CYTED - Programme Ibéro-Américain de Science et Technologie pour le Développement, de zonage vitivinicole (Cyted, 2003 ; Sotés & Tonietto, 2004). L’objectif a été de caractériser l’effet du climat viticole sur la typicité des vins sur la macro région viticole Ibéro-Américaine. MATERIEL ET MÉTHODE La méthodologie a été appliquée à un ensemble de 45 des principaux régions viticoles situées sur 6 pays Ibéro-Américains : Argentine (Catania et al., 2007), Bolivie, Brésil, Chili, Espagne et Portugal. Le climat viticole de chaque région viticole a été caractérisé par les 3 indices climatiques viticoles du Système CCM Géoviticole (Tonietto, 1999 ; Tonietto & Carbonneau, 2004) : IH (Indice Héliothermique de Huglin), IF (Indice de Fraîcheur des Nuits) et IS (Indice de Sécheresse). Les indices ont été calculés en utilisant les moyennes climatiques interannuelles d’un poste météorologique représentatif du climat viticole de chaque région. Les caractéristiques sensorielles moyennes observées de façon fréquente sur les principaux vins rouges secs (jusqu’à l’âge de 12 mois après fermentation alcoolique) élaborés avec le (s) cépage (s) le plus représentatif (s) de chacune des 45 régions viticoles ont été décrites, basée sur les connaissances empiriques, par des œnologues experts en évaluation sensorielle de chaque pays, an utilisant la méthodologie proposée par Zanus & Tonietto (2008). La caractérisation sensorielle réalisée concerne l’intensité de la perception des descripteurs suivants des vins, qui sont très influencés par le climat viticole : Couleur (Cou), Arôme Total (Ar), Arôme – fruit mûr (Ar-Fm), Concentration (Con), Alcool (Al), Tanins (Tan) et Acidité (Ac). La Longueur en Bouche (Lon) a été également évaluée. Les experts ont utilisé un 23 - 18 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 18 03/06/10 15:48
  19. 19. formulaire de caractérisation sensorielle (Tableau 1), avec une échelle de perception sensorielle de l’intensité, qui varie de l’intensité baisse (1) à l’intensité haute (5), classé selon la variabilité d’intensité observée sur les vins à l’échelle mondiale. Tableau 1. Formulaire de caractérisation sensorielle des vins rouges des régions viticoles. Les données ont été soumises à l’analyse des corrélations pour l’ensemble des variables et à l’Analyse en Composantes Principales (ACP). RÉSULTATS ET DISCUSSION Le Tableau 2 montre les moyennes et l’écart-type des indices climatiques viticoles du Système CCM et des variables sensorielles des 45 régions viticoles. Le IH a présenté une valeur moyenne de 2.398, avec la valeur minimale de 1.700 et la valeur maximale de 3.294 ; le IF a présenté une valeur moyenne de 13,3°C, avec une valeur minimale de 8,1°C et une valeur maximale de 21,0°C ; et le IS a présenté une valeur moyenne de –71 mm, avec une valeur minimale de –276 mm et une valeur maximale de 200 mm, excepte pour les climats très frais. On observe une très bonne représentation de la variabilité observée au niveau de la viticulture mondiale. Les valeurs moyennes sur l’ensemble des variables sensorielles se situent entre 3,0 (Ac) et 3,7 (Al). L’écart-type sur l’ensemble des variables sensorielles se situe entre 0,67 (Al) et 0,81 (Ar-Fm et Ac). Tableau 2. Moyenne et l’écart-type des indices climatiques du Système CCM et variables sensorielles pour l’ensemble des 45 régions viticoles de l’étude. Le Tableau 3 présente les coefficients de corrélation des indices climatiques du Système CCM et variables sensorielles pour l’ensemble des 45 régions viticoles de l’étude, avec le niveau de significance statistique. 3 IH IF IS Cou Ar Ar-Fm Conc Al Tan Ac Lon Moyenne 2398 13,3 -71 3,7 3,6 3,6 3,6 3,7 3,4 3,0 3,6 Ecart-type 363,69 2,87 114,73 0,88 0,72 0,81 0,75 0,67 0,72 0,81 0,75 Baisse Haute Couleur - intensité Arôme - intensité Arôme - fruit mûr - intensité Concentration - intensité Alcool - intensité Tanins - intensité Acidité - intensité Longueur en bouche Descripteur sensoriel Tendance de l'intensité 3 - 19 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 19 03/06/10 15:48
  20. 20. Tableau 3. Coefficients de corrélation des indices climatiques du Système CCM et variables sensorielles pour l’ensemble des 45 régions viticoles de l’étude. * Significatif au niveau de 5% de probabilité. ** Significatif au niveau de 1% de probabilité. Les résultats montrent une corrélation significative entre indices climatiques viticoles et les variables sensorielles pour : IH – positive avec Al et négative avec Ac ; IS – positive avec Ac et négative avec Al et Ar-Fm ; IF – négative avec Cou, Ar, Con, Tan et Lon. La Figure 1 présente le cercle des corrélations de l’Analyse en Composantes Principales (ACP) des indices climatiques du Système CCM et variables sensorielles pour l’ensemble des 45 régions viticoles de l’étude. Les composantes principales 1 et 2 expliquent 64,67% de la variabilité. L’ACP renforce les résultats du Tableau 3. Figure 1. Cercle des corrélations de l’Analyse en Composantes Principales (ACP) des indices climatiques du Système CCM et variables sensorielles pour l’ensemble des 45 régions viticoles de l’étude. 4 IH IF IS Cou Ar Ar-Fm Con Al Tan Ac Lon CP 1 : 38,46% d’inertie -1,0 0,0 1,0 -1,0 0,0 1,0 Positionnement des variables sur le cercle des corrélations CP2:26,21%d’inertie Variable IH 1,00 - - - - - - - - - - IF 0,53 ** 1,00 - - - - - - - - - IS -0,34 * 0,12 1,00 - - - - - - - - Cou -0,23 -0,49 ** -0,09 1,00 - - - - - - - Ar 0,15 -0,33 * -0,21 0,43 ** 1,00 - - - - - - Ar-Fm 0,17 -0,27 -0,46 ** 0,46 ** 0,66 ** 1,00 - - - - - Con -0,11 -0,34 * -0,03 0,74 ** 0,52 ** 0,50 ** 1,00 - - - - Al 0,49 ** 0,11 -0,55 ** 0,13 0,26 0,37 * 0,23 1,00 - - - Tan -0,18 -0,39 ** -0,01 0,75 ** 0,26 0,26 0,72 ** 0,01 1,00 - - Ac -0,59 ** -0,26 0,44 ** 0,40 ** -0,21 -0,02 0,36 * -0,47 ** 0,48 ** 1,00 - Lon -0,09 -0,41 ** -0,23 0,59 ** 0,71 ** 0,63 ** 0,62 ** 0,20 0,37 * 0,06 1,00 IH IF IS Cou Tan Ac LonAr Ar-Fm Con Al 3 - 20 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 20 03/06/10 15:48
  21. 21. Les résultats confirment l’effet des températures (IH) sur l’augmentation, surtout de la perception l’alcool et sur la réduction de la perception de l’acidité des vins rouges. La réserve en eau du sol montre que les valeurs les plus élevées de IS contribuent, surtout, à augmenter la perception de l’acidité et à réduire la perception de l’alcool et de l’intensité de l’arôme (fruit mûr). L’effet des nycto températures en période de maturation du raisin sur plusieurs caractéristiques sensorielles des vins a été mis en évidence : les nuits fraîches en période de maturation (les valeurs les plus baisses de IF), favorisent la perception de la couleur, des tannins, de l’arôme, de la concentration et de la longueur en bouche. Evidement que la caractérisation sensorielle de chaque région n’est pas seulement l’expression de l’effet climatique. Bien au contraire, elle intègre également la grande variabilité associé aux différents cépages et ses interactions avec le milieu physique, aux systèmes viticoles et à l’ensemble des pratiques œnologiques adoptées par chaque région. De toute façon, l’utilisation des résultats obtenues et d’autres dans l’avenir en reliant l’effet du climat sur la typitité des vins peut servir aussi pour avoir une idée de la typicité espéré pour des vins à produire dans des nouvelles régions potentielles pour la viticulture et pour avoir une idée quantifiée du changement de typicité des vins des régions productrices en fonction du changement climatique. CONCLUSIONS L’étude indique qu’une partie de la typicité des vins est déterminée par le climat viticole des régions et que les indices du Système CCM Géoviticole sont pertinents pour les relier aux caractéristiques sensorielles des vins. L’effet de l’Indice Héliothermique et de l’Indice de Sécheresse à été confirmé sur les variables sensorielles, surtout sur l’alcool, sur l’acidité et sur l’intensité de l’arôme. Le déterminisme de l’Indice de Fraîcheur des Nuits sur la perception sensorielle des vins – couleur, arôme, tannins, persistance, à été mis en évidence. REMERCIEMENTS On voudrait remercier tout d’abord au CYTED pour avoir possibilité le développement du projet qui est à l’origine de ce travail et a toutes les institutions de recherche et développement des pays impliqués. À la FINEP – Financiadora de Estudos e Projetos, pour l’appuie à la consécution du travail au Brésil. Egalement, aux diverses institutions qu’ont fourni les bases des données climatiques des régions viticoles de l’étude et aux œnologues experts de tous les pays pour l’évaluation sensorielle des vins des régions viticoles. BIBLIOGRAPHY Catania, C.D.; Avagnina de del Monte, S.; Uliarte, E. M.; F. del Monte, R.; Tonietto, J. 2007. El clima vitícola de las regiones productoras de uvas para vinos de Argentina. In: Tonietto, J.; Sotés, V. (Ed.). Caracterização climática de regiões vitivinícolas ibero-americanas. Bento Gonçalves: Embrapa Uva e Vinho. p.9-55. Disponible à : <http://www.cnpuv.embrapa.br/ccm>. Cyted. 2003. Metodologías de zonificación y su aplicación a las regiones vitivinícolas Iberoamericanas. Madrid. 20p. (Proyecto de Investigación Cooperativa; Coodinacion de Vicente Sotés Ruiz - UPM, España). Sotés, V.; Tonietto, J. 2004. Climatic zoning of the Ibero-American viticultural regions. In: Joint International Conference on Viticultural Zoning, 2004, Cape Town. Proceedings. Cape 5 3 - 21 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 21 03/06/10 15:48
  22. 22. Town, South Africa, South African Society for Enology and Viticulture-OIV-GESCO. p. 202. CD-ROM (Viticultural Terroir Zoning 2004). Tonietto, J. 1999. Les macroclimats viticoles mondiaux et l'influence du mésoclimat sur la typicité de la Syrah et du Muscat de Hambourg dans le sud de la France : méthodologie de caractérisation. (Thèse Doctorat). École Nationale Supérieure Agronomique de Montpellier - ENSA-M. 233p. Tonietto, J.; Carbonneau, A. 2004. A multicriteria climatic classification system for grape- growing regions worldwide. Agricultural and Forest Meteorology, 124/1-2, 81-97. Zanus, M. C.; Tonietto, J. 2007. Elementos metodológicos para a caracterização sensorial de vinhos de regiões climáticas vitivinícolas. In: Tonietto, J.; Sotés, V. (Ed.). Caracterização climática de regiões vitivinícolas ibero-americanas. Bento Gonçalves: Embrapa Uva e Vinho, p.57-64. Disponível em: <http://www.cnpuv.embrapa.br/ccm>. 6 3 - 22 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 22 03/06/10 15:48
  23. 23.     (1) (1) (1) Department of Environment and Soil Science. University of Lleida. Alcalde Rovira Roure 191, 25198, Lleida, Spain cramos@macs.udl.es; j.martinez@macs.udl.cat    This study present a detailed analysis of the rainfall and temperature changes in the Penedès region in the period 19959 200809, in comparison with the trends observed during the last 50 years, and its implications on phenology and yield. Temperature increases are higher than in previous time periods, which together with the irregular rainfall distribution throughout the year give rise to significant water deficits for vine development. Water deficits are being exacerbated during the last years by the increase of temperatures which imply an increase of evapotranspiration. The dates at which each phenological stage starts and the length of the different phenological stages are affected by temperature (accumulated degreedays and daily air temperature difference), precipitation and water accumulated into the soil. Winegrape yield was also influenced by soil water availability.   Evapotraspiration Mediterranean climate E Spain phenology trendsyield   Climate change and its potential impacts on viticulture and viniculture have become increasingly important as a consequence of changes in earth surface characteristics associated with the increase in greenhouse gases and changes in global temperatures, radiation budget and hydrological cycles. Vines, one of the most extensive crops in some parts of the Mediterranean Spanish area, which are cultivated under rainfed conditions, may therefore be one of the crops that suffer the consequences of climate change. According to Olesen and Bindi (2002), in the current production areas the yield variability (fruit production and quality) may be higher in the future than it is at present. However, some areas may suffer negative effects such as water stress due to a reduction in water availability and shortening of the ripening period, with harvest occurring during time with high temperatures, which may have negative impacts on wine quality (Duchêne and Schneider, 2005). Examples of impacts of temperature changes, frost occurrence and growing season lengths on grape productivity are found in the literature (Jones et al., 2005). The Mediterranean climate is characterized by dry and warm summers and two wet seasons (spring and autumn), in which most rainfall is recorded, but there is high variability from year to year. Some authors indicate decreasing precipitation trends for the Mediterranean (Karl, 1998) and significant changes in extreme events concentrated in a small number of events such as more frequent and extreme droughts, increases in cool season precipitation, and warm season drying (Easterling et al. 2000). This study presents an analysis of temperature and precipitation and their 3 - 23 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 23 03/06/10 15:48
  24. 24. possible impacts on grape development in the Alt Penedès (NE Spain), which is dry farming area with a long tradition on vine cultivation but with significant changes during the last decades.      The Alt Penedès region, located in the northeast Spain, is part of the Penedès Tertiary DepressionThe main soil types in the area are                (MartínezCasasnovas and Ramos, 2009). Calcilutites (marls) are the main lithological material, with occasional sandstones and conglomerates and due to labours carried out in the field to facilitate labour mechanization, soil profiles have been disturbed, leaving on top of the surface materials which are poor in organic matter and very week soil structure. This affects water intake and further redistribution, with an important limitation of water availability for the vine. The climate is Mediterranean, with a mean annual temperature of 15ºC and a mean annual rainfall of 550 mm, mainly concentrated in spring (April to June) and autumn (September to November). Highintensity rainstorms are particularly frequent in autumn. The Alt Penedès area has a long tradition of vineyard cultivation under the Penedès and Cava Designation of Origins (DO). Vineyards are the main land use, representing 80% of the cultivated area, about 17500 ha (CRDOP, 2008), (about 67% of the DO surface) 82% of them planted with white varieties, being the most representative: Xarelo (31%), Macabeo (25.7%), Parellada (18.6%) and Chardonnay (5%). Among the red varieties Cabernet Sauvignon (4.3%) and Merlot (7.3%) are the most extended (CRDOP, 2008). At present, about 50% of vineyards have been transformed into new vineyards, in which almost all labours are mechanised. For this study four observatories distributed in the area and two vineyards close to them are considered to asses the effects of climate trends on production and phenology.   Precipitation and temperature data were recorded in Vilafranca del Penedès (VP) (41.434º; 1.419E; 230 m) from 1952 to 2009 and in Sant Sadurní d’Anoia (SSA) (41,208º; 1.791E; 164 m), La Granada (LG) (41.367º; 1.724E; 238 m) and Els Hostalets de Pierola (EHP) (41.526º; 1.805E; 312 m) from 1996 to 2009. Daily rainfall, maximum and minimum temperatures and evapotranspiration were analysed for the growing season (AprilSeptember) and for each phenological stage (budbreakbloom [], bloomveraison [V] and ripening [R]). Additionally, several bioclimatic indexes such as accumulated effective temperature [Tef(Tm 10ºC)] and Huglin [HI] and Winkler [WI] indexes were analyzed. Dates at which each phenology stage started was examined in two vineyards planted with Xarelo: beginning of budbreak, early bloom (beginning of flowering, grapes colour change and grapes ripe for harvesting. In the text, the different stages are identified as: dormant period (D): time between 1srt Novemberbudbreak start; budbreakbloom (); bloomveraison (V); ripening (veraisonharvest: R), post harvest (PH): time between harvest and 31st October. The length of each phenological period was evaluated for each year. Crop yield was also evaluated in the same vineyards. The ratio between precipitation and crop evapotranspiration, estimated using the crop coefficients proposed by the FAO (Allen et al., 1998), was evaluated as well as the relationship between temperature and the related indexes and the date at which the different phenological events took place. Results related to Xarelo variety are presented. In addition, the relationship between grape production and temperature and water 3 - 24 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 24 03/06/10 15:48
  25. 25. availability was analysed. For these analysis, a step multiple regression analysis (forward variable selection) was performed using the Statgrapics 5.1 software.   Table 1 shows the mean values of climate parameters related to the growing season (GS) recorded in four observatories in the area during the period (19962009). The mean temperature (TGSM) ranged between 18.7 and 22.2ºC, with mean maximum temperature (TGSMax) ranging between 23.8 and 25.9 and mean minimum temperatures (TGSMin) ranging between 12.4 and 13.7ºC. During the last decades, increasing mean, maximum and minimum temperature trends were observed in the growing season in this study area (Ramos et al., 2008). Growing season mean temperatures increased in about 0.04ºC/year in VP, during the last 50 years, which implies and increase of about 2.2 ºC in the period (19522006). If we focus on the last 14 years (19962009), the trend of the mean temperature is similar (0.038 ºC/year), but the minimum temperature seems to increase much more than in previous decades (ranging between 0.105 and 0.149ºC/year depending on the observatory). Other bioclimatic indices which also showed significant increasing trends during the past decades such as the Winkler index (trend=7.81GDD/year) or the Huglin index (7.24GDD/year), show now higher values in VP (20.9 and 22.2 DDD/year), although lower values are found in other observatories (e.g. (8.23 and 11.2 GDD/year, respectively in EHP and 6.5 GDD/year in LG). While the mean WI index value during the past decades (1860 GDD) places this region in Winkler region III (Ramos et al., 2008), it is observed that at present the mean values are clearly in region IV. This means the need of adapting some varieties to this new situation. Particularly, some of the most extended varieties in the region could be affected (Parellada or Chardonnay). One of the direct consequences of the temperature increase is the higher evapotranspiration rates. During the last 14 years evapotraspiration rates showed a significant positive trend in all observatories. However, those ratios were on average 9.3 mm/year in SSA, 11.1 mm/year in and EHP and about 3 mm/year in VP and LG, observatory where the average evapotranspiration was already higher. This increase means an annual evapotraspiration increase ranging between 1 and 2.3%.        The rainfall characteristics of the Mediterranean climate, with high variability from year to year and within the year, makes difficult to confirm precipitation trends. At annual scale no significant trends may be confirmed, but higher variability may be observed: rainfall increases in winter and autumn and decreases in spring, mainly affecting the bloomveraison stage. A significant decrease ranging between 4.6 and 5.9 mm/year was observed in that period, which represent about 10% of the rainfall recorded during that crop stage. The irregular distribution of the rainfall and its decrease during the growing period makes, that very often, the vines suffer deficits which may not be covered by the water reserves accumulated into the soil profile. Using the data belonging to one of the observatories included in this analysis (EHP) an analysis of the water availability for the crop during the last years was done. In this analysis the relationship between rainfall and evapotranspiration in each crop stage as well as the accumulated water from the previous stage was considered. 3 - 25 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 25 03/06/10 15:48
  26. 26. Figure 1a shows the water available (P ETc) from the dormant period to the end of crop cycle. In only five (1996, 1997, 2002, 2004 and 2007) of the 14 years included in the analysis, precipitation exceed evapotranspiration needs during the whole growing cycle. In four years more (1999, 2000, 2004 and 2008) precipitation recorded during the dormant period helped to cover water needs during the budbreakbloom stage, but during the rest of the year, the plant suffer significant water deficits. However, there were some years, dry years or years with very irregular distribution, in which the accumulated precipitation was not enough to cover evapotraspiration in any stage of the whole growing season (2001 and 2005). Even more, taking into account the rainfall intensity and the limited soil infiltration capacity in many cases, water restrictions are even higher. A specific study carried out in two vineyards planted with Xarelo, one of the varieties most commonly extended in the area, shows how water deficits recorded, not only during the ripening period but in earlier stages, are even higher. We can see how water deficits during the bloom to veraison and during the ripening period were significantly increased in almost all years (Fig. 1b). These water deficits are affected for both irregular distribution and higher temperatures, which gave rise to higher evapotranspiration rates. Under these results we could understand the difficulty of extracting general conclusions. Even in the case that total precipitation does not change so much, it is clear that a decrease of precipitation during some stages of the crop have additional effects.  Table 1: Mean temperature and precipitation indices and trends covering the growing period in four observatories of the study area (19962009) Vilafranca del Penedès Trend/ year La Granada Trend /year Sant Sadurní D’Anoia Trend/ year Els Hostalets de Pierola Trend/ year TGSM 19.8±0.9 0.102* 19.4±0.5 22.2±3.3 18.7±0.9 0.038 TGSMax 24.0±1.3 0.105* 25.9±0.8 25.2±0.9 0.106 23.8±0.8 0.149* TGSMin 13.5±0.9 0.108* 13.7±0.4 0.072* 12.4±0.7 0.084 12.9±0.9 0.068 WI 2104±140 20.9* 2119+180 6.5 * 2120+180 35.2 2066+160 11.9* HI 2813±150 22.2* 2573±170 12.8 2575±170 27.5 2385±130 8.23* PGS 336±110 322±100 322±120 350±150 ETcGS 414±18 2.7 * 482±20 3.8 * 322±120 9.32 * 366±100 11.1 * PBB 68±50 81±60 87±60 79±60 PBV 47±30 5.34* 34.2±30 4.84 * 36±30 4.6 * 76±70 5.9 * PR 103±38 125±20 96±45 90.6±70 * means significant differences at 95% level      According to the Consell Regulador de la Denominació d’Origen Penedès, the ranks of the vintage from the region are given as good, very good and excellent for both white and red wines. In 12 out of the last 15 years the vintage qualification was very good plus one more excellent (CRDOP, 2010). From this point we could think that there is not a serious impact of climate or water availability on the sector despite different authors having already pointed out the impacts that climate change could have on wine quality (Duchêne and Schneider, 2005; White et al., 2006; Makra et al., 2009). However, water availability may have a direct impact on yield with a significant economic impact for the sector. In order to evaluate the relationship between grape production and temperature and water stored into the soil, a step multiple regression analysis (forward variable selection) was performed. Although several variables related to temperature and soil water have influence on yield when they are tested isolated (negative effect: effective temperature corresponding to D+BB period [(Tef_D+BB), to BV period (Tef_BV) or to the whole growing 3 - 26 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 26 03/06/10 15:48
  27. 27. season (Tef_WGS); positive effect: accumulated water during D+BB period (WA_D+BB)], if all these variables are combined in a multiple regression analysis, the only significant value was the accumulated water during the budbreakbloom stage, which represents about 47% of total variance (Tab. 2). Fig. 1. Water availability during each stage of the growing period (BB: budbreakbloom; BV: bloomveraison; R: ripening) of a vineyard planted with Xarelo): a) precipitation – evapotranspiration in each stage: b) precipitationrunoff evapotranspiration in each stage On the other hand, variables related to phenology such as the dates at which different phenological stages start are also influenced by water availability as well as by temperature. In particular, a significant correlation was found for this variety between the data at which veraison starts and the effective temperature during the bloomveraison period (negative correlation, which represents about 29% of total variance), and between that variable and the water available during the same period (positive correlation, representing about 38% of the variance) (Tab. 2) Tab. 2. Fit parameters for Xarelo grapevine yield and some phenological dates in relation to effective temperature during the bloomveraison period (Tef_BV)) and soil water available during budbreakbloom (WA_BB) and during bloomveraison (WW_BV) periods Variety variable parameter R2 (%) FRatio PValue Xarelo Yield (kg/ha) Constant WA_BB 17.97 43.47 6.92 0.04 Veraison data Tef_BV WA_ BV 0.106 0.081 28.78 37.95 4.04 6.11 0.07 0.02   The high variability of the Mediterranean climate together with the high intensity rainfall and the increasing temperature trends give rise to significant water deficits for vine development in the Penedès region, in which vineyards have been cultivated for centuries without irrigation. Significant water deficits have been observed not only in dry years but also in years with total rainfall above the mean value in the area. Water deficits during the growing season may be in part supplemented by water accumulated during the dormant period, but in most years water balance is negative for the whole growing period. Water deficits are being exacerbated during the last years by the increase of temperatures, which results in an increase of evapotranspiration. Winegrape yield and the dates at which each phenological stage starts are affected by temperature (accumulated degreedays) and by soil water availability. -250 -200 -150 -100 -50 0 50 100 150 200 250 300 96 97 98 99 00 01 02 03 04 05 06 07 08 09 Wateravailable(mm) BB BV R -250 -200 -150 -100 -50 0 50 100 150 200 250 300 Wateravailable(mm) BB BV R 96 97 98 99 00 01 02 03 04 05 06 07 08 09 -250 -200 -150 -100 -50 0 50 100 150 200 250 300 96 97 98 99 00 01 02 03 04 05 06 07 08 09 Wateravailable(mm) BB BV R -250 -200 -150 -100 -50 0 50 100 150 200 250 300 Wateravailable(mm) BB BV R 96 97 98 99 00 01 02 03 04 05 06 07 08 09 a b -250 -200 -150 -100 -50 0 50 100 150 200 250 300 96 97 98 99 00 01 02 03 04 05 06 07 08 09 Wateravailable(mm) BB BV R -250 -200 -150 -100 -50 0 50 100 150 200 250 300 Wateravailable(mm) BB BV R 96 97 98 99 00 01 02 03 04 05 06 07 08 09 -250 -200 -150 -100 -50 0 50 100 150 200 250 300 96 97 98 99 00 01 02 03 04 05 06 07 08 09 Wateravailable(mm) BB BV R -250 -200 -150 -100 -50 0 50 100 150 200 250 300 Wateravailable(mm) BB BV R 96 97 98 99 00 01 02 03 04 05 06 07 08 09 a b 3 - 27 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 27 03/06/10 15:48
  28. 28. The lack of water resources in the area makes very difficult or excessively expensive to implement irrigation systems in the fields, and because of that vineyards may be seriously affected if temperature continues increasing. Water deficits, driven by the irregularly rainfall distribution and the increase of evapotranspiration in the stages in which vine water needs should not be restricted, may challenged the sustainability of some vineyards in the area. On the other hand, yield may be reduced due to higher water stress under a scenario of climate change.  This work was developed in the framework of the AMB1995158, AMB980481, REN2002 0042, AGL200500091AGR, AGL2009,085 research projects financed by the Spanish Ministry of Science and Innovation, developed in the same study area. Authors want to thank the farmer of the field for the information given about his vines.   CRDOP (Consejo Regulador Denominación de Origen Penedès), 2008. Anuario estadstico 200 2008. Generalitat de Cataluña, Barcelona 24 pp CRDOP (Consejo Regulador Denominación de Origen Penedès), 2010. Anyades D.O. Penedès (Vintages D.O. Penedès). http://www.dopenedes.es/includes/estadistiques/anyades _do _penedes_cat.pdf Duchêne E., Schneider C., 2005. Grapevine and climatic changes: A glance at the situation in Alsace.  24: 999 Easterling DR., Meehl GA., Parmensan C., Chagnon SA., Karl T., Mearns LO., 2000. Climate extremes: observation, modelling and impacts.  289: 2068204. Jones GV., 2005. Climate change in the western United States grape growing regions.  . 689: 41–60 Jones GV., White MA., Cooper OR., Storchmann K., 2005. Climate change and global wine quality.  : 194. Karl TR., 1998. Regional Trends and Variations of Temperature and Precipitation. In Watson, R.T., Zyinyowera M.C. and Moss R.H. (eds),  . IPCC. Cambridge University Press. pp. 4114. Makra L., Vitányi B., Gál A., Mika J., Matyasovszky I., Hirsch T. 2009. Wine Quantity and Quality Variations in Relation to Climatic Factors in the Tokaj (Hungary) Winegrowing Region. 60: 1221. MartnezCasasnovas JA., Ramos MC., 2009. Soil alteration due to erosion, ploughing and levelling of vineyards in north east Spain.  25: 18192. Olesen JE., Bindi M., 2002. Consequences of climate change for European agricultural productivity, land use and policy. European Journal of Agronomy 16: 29262. Soil Survey Staff, 2006. Soil survey staff, keys to soil taxonomy. Department of Agriculture Soil Conservation Service, Washington D.C. U.S. White MA., Diffenbaugh NS., Jones GV., Pal JS., Giorgi F., 2006. Extreme heat reduces and shifts United States premium wine production in the 21st century. PNAS 10 (0): 1121 11222. 3 - 28 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 28 03/06/10 15:48
  29. 29. EFFETTI DEL CAMBIAMENTO CLIMATICO EUROPEO SULLE EPOCHE DI VENDEMMIA IN ABRUZZO B. Di Lena(1), (2) , L. Mariani(3) , F. Antenucci(2) , O. Silvestroni(1) (1) Dip. Scienze Ambientali e delle Produzioni Vegetali, Università Politecnica delle Marche, Via Brecce bianche, 60131 Ancona. (2) Regione Abruzzo – Arssa - Centro Agrometeorologico Regionale, C.da Colle Comune, 66020 Scerni (Chieti). (3) Università di Milano- Dipartimento di Produzione Vegetale, Via Celoria, Milano Riassunto I dati termo-pluviometrici del periodo 1971-2009 registrati da alcune stazioni della regione Abruzzo sono stati analizzati adottando alcuni semplici indici climatici e bioclimatici. E’ stato valutato il verificarsi di cambiamenti climatici così come le loro ripercussioni sulle date di inizio vendemmia. La data di vendemmia è risultata significativamente influenzata dalle disponibilità termiche e in particolare dalle Ore Normali di Caldo (NHH) cumulate nel periodo marzo-giugno. L’analisi statistica dei trend temporali dell’ accumulo di NHH in marzo-giugno ha individuato una discontinuità climatica che ricade nel 1984 per la collina litoranea centrale, nel 1997 per la collina litoranea meridionale e nel 1998 per la collina interna del pescarese. Questi punti di discontinuità sono risultati in buon accordo con i punti di discontinuità delle date di inizio raccolta e possono pertanto rappresentare lo spartiacque tra la precedente e l’attuale fase climatica. Quest’ultima si caratterizza per un anticipo della data di raccolta rispettivamente di 10 giorni per la collina litoranea meridionale , 15 per la collina litoranea centrale e 14 per la collina interna. Parole chiave Vitis vinifera, fenologia, ore normali di caldo Abstract Thermo-pluviometric data registered in the period 1971-2009 by three hillside stations of the Abruzzi located in maritime areas (central and southern part of the region) and in the internal zone were analyzed adopting some simple climatic and bioclimatic indices. Occurrence of climate change was evaluated as well as its influence on harvest dates. Harvest dates were significantly influenced by thermal availability, mainly when it was measured by Normal Heat Hours referred to the period March-June (NHH march-june). The statistical analysis of the temporal trends of NHH march-june has identified change-points occurred in a lapse of time from 1984 to 1998. The first abrupt change happened in central maritime area (1984), followed in 1997 and 1998 seasons by change-points respectively registered in southern maritime area in the internal zone. These NHH march-june break-points were in a good relationship with harvest date break-points and seem to well represent the watershed between the previous and the current climatic phase. This latter is characterized by an advance in harvest date around 10 days in southern maritime area and averaging 14-15 days in central maritime area and internal zone. Key-words Vitis vinifera, climate change, harvest date 3 - 29 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 29 03/06/10 15:48
  30. 30. Introduzione Le recenti annate caratterizzate da siccità primaverile-estiva hanno alimentato il dibattito sui probabili impatti dei cambiamenti climatici in specifici areali viticoli e molto interesse è stato rivolto alle loro possibili ripercussioni sulla fenologia della vite e sulle date di vendemmia. Riteniamo che un tale dibattito non possa prescindere dagli aspetti di scala in virtù dei quali i cambiamenti climatici a livello di macroclima, che nelle medie latitudini del pianeta sono di norma il frutto di riconfigurazioni nella circolazione generale, si propagano al mesoclima (clima di areali viticoli relativamente ampi) e da questo al microclima (clima del singolo vigneto). Da questo angolo di visuale un elemento cruciale per la viticoltura europea è rappresentato dal brusco cambiamento climatico dovuto al mutato regime del grande vortice polare e di conseguenza delle grandi correnti occidentali (westerlies) che ha interessato le medie latitudini dell’emisfero boreale negli anni ’80 del 20° secolo (Werner et al., 2000) e che per l’areale europeo viene efficacemente descritto dal comportamento della NAO (North Atlantic Oscillation), indice circolatorio a macroscala che dal 1981 manifesta una sensibile anomalia positiva (Mariani, 2008). Le più immediate conseguenze a livello europeo di tale brusco cambiamento climatico sono state l’affievolirsi dell’apporto invernale di masse d’aria polare continentale (PC, la gelida aria siberiana) e l’aumentato apporto di masse d’aria subtropicale marittima (STm). Da tali fenomeni è disceso un aumento delle temperature medie annue di circa 0,5-1°C nelle parti più settentrionali dell’areale viticolo europeo (tipo Cfb di Koeppen) e di 1-1,5°C nelle parti più meridionali dello stesso (tipo Csa di Koeppen). Meno univoci sono invece da considerare gli effetti sul quadro pluviometrico, anche se è noto che le fasi a NAO positivo si caratterizzano per una maggiore aridità negli areali a clima Csa (Trouet et al., 2009). Fra le conseguenze più evidenti di tali fenomeni rientra l’anticipo di 6-25 giorni delle principali fasi fenologiche della vite (fioritura, invaiatura e vendemmia) segnalato da Jones et al. (2005) per alcuni vitigni coltivati in diversi siti. Per cogliere le modalità con cui il cambiamento climatico europeo degli anni ’80 si è manifestato nelle diverse aree viticole italiane in è necessario spingere l’analisi fino alla mesoscala, considerando singolarmente territori non molto estesi, come quello dell’Abruzzo, una regione ad orografia complessa dove la viticoltura è diffusa sia nella zona della collina litoranea che in quella della collina interna. Per questa Regione, l’analisi di alcuni indici statistici e bioclimatici ricavati da serie storiche di dati termo-pluviometrici giornalieri del periodo 1965-2007, ha evidenziato, durante il ciclo vegetativo, una diminuzione delle precipitazioni nella fascia costiera e un aumento delle temperature nelle aree interne (Silvestroni et al., 2008). La stessa indagine ha evidenziato lungo la fascia collinare litoranea un aumento dell’indice di Huglin nel decennio antecedente al 2007. Alla luce di questi presupposti il presente lavoro è stato mirato a cogliere gli effetti del cambiamento climatico sulle date di inizio vendemmia, analizzando in particolare le informazioni provenienti dai registri di tre importanti cantine abruzzesi e riferite al periodo 1974-2009 con lo scopo di porre in luce: - le relazioni tra date di inizio vendemmia della cv. Montepulciano e alcuni indici climatici e bioclimatici ricavati da serie storiche di dati termo-pluviometrici. - l’eventuale presenza di discontinuità nelle serie storiche delle date di inizio vendemmia (“change points”) e degli indici bioclimatici applicando opportune metodologie statistiche (Bai e Perron, 1998 e 2003). 3 - 30 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 30 03/06/10 15:48
  31. 31. Materiali e Metodi Lo studio delle serie storiche di date di inizio vendemmia della cv. Montepulciano nella Regione Abruzzo, è stato effettuato utilizzando le informazioni ricavate dai registri delle cantine di Scerni, Vacri e Loreto Aprutino. Per le prime due, localizzate rispettivamente nella collina litoranea meridionale e centrale della provincia di Chieti, è stato considerato il periodo 1974-2009, mentre per l’ultima localizzata nella collina interna della provincia di Pescara è stato analizzato il periodo 1977-2009 (Fig.1). La valutazione delle relazioni esistenti fra indici climatici e bioclimatici da un lato, e serie storiche delle date di inizio vendemmia dall’altro, è stata effettuata utilizzando i dati termo-pluviometrici giornalieri del Servizio Idrografico Regionale. Il data set era composto dai valori delle temperature massime e minime e delle precipitazioni giornaliere. La temperatura media giornaliera è stata ottenuta facendo la semisomma dei valori delle temperature massime e minime. Prima di procedere ai normali controlli di consistenza interna e persistenza temporale delle serie storiche sono state verificate le informazioni sulle stazioni di rilevamento, che non hanno subito, nel periodo considerato, modifiche tecniche e di posizione tali da inficiare l’attendibilità dei dati rilevati. In particolare per la collina litoranea meridionale sono stati impiegati i dati della stazione di Scerni, per la collina litoranea centrale quelli di Chieti, e per la collina interna quelli di Penne (Fig. 1) Nel periodo aprile ottobre sono stati determinati: la temperatura media (ottenuta facendo la media dei valori medi giornalieri), il numero di giorni con temperature massime superiori a 30°C, le precipitazioni totali e la media delle escursioni termiche giornaliere (espresse come differenza fra temperature massime e minime). Nel periodo aprile settembre sono stati determinati per le tre località i tre indici proposti da Tonietto e Carbonneau (2004) per la classificazione degli areali viticoli secondo un approccio multicriteriale: Indice eliotermico di Huglin, Indice di Freschezza della notte (media delle temperature minime del mese di settembre) e Indice di Siccità (stima della disponibilità potenziale di acqua nel suolo). Nello stesso periodo sono state determinate anche le ore normali di caldo (NHH) e la sommatoria delle temperature attive considerando quale soglia termica 10°C. Le NHH hanno consentito di valutare quantitativamente l’efficacia di ore trascorse a temperature diverse, evidenziando l’accumulo complessivo di risorse termiche utili per il processo indagato. Il valore della funzione normalizzata è pari a 0 sia con valori termici inferiori a 7°C (Cardinale minimo - Cmin) che maggiori di 35°C (Cardinale massimo - Fig.1 – Localizzazione degli areali oggetto dello studio  Stazione meteorologica  Cantina 3 - 31 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 31 03/06/10 15:48
  32. 32. Cmax) mentre è pari a 1 se la temperatura assume il valore ottimale di 26°C (Cardinale ottimale - Copt). L’equazione adottata è quella descritta da Wang e Engel (1998): Fvn(T) =(2(T-Cmin) *(Copt-Cmin)  *(T- Cmin) 2 )/(Copt –Cmin) se Tmin <=T<=Tmax e Fvn(T) =0 se T<Cmin e T>Cmax ove :  = ln(2/ln((Cmax-Cmin)/(Copt-Cmin))) Ai fini del calcolo delle NHH, le temperature orarie sono state ottenute dalle temperature massime e minime applicando l’algoritmo di Parton e Logan (1981). Per il mese di settembre, assunto come periodo di pre-vendemmia, sono state inoltre calcolate le precipitazioni totali e la media delle escursioni termiche giornaliere. Le relazioni tra le serie storiche delle date di inizio vendemmia (espresse come numero di giorni a decorrere dal 1 aprile) e gli indici climatici e bioclimatici sono state determinate con l’approccio statistico della regressione lineare semplice. La presenza di discontinuità nell’andamento delle serie storiche (Todaro e Migliardi, 2000, 2003 e 2004) è stata indagata utilizzando l’algoritmo di analisi di “change point”, presente nella libreria Strucchange del software R - http://www.r-project.org (Bai e Perron, 1998 e 2003). Risultati e discussione La caratterizzazione climatica, basata sui valori medi degli indici climatici e bioclimatici, ha mostrato una elevata similarità delle località di Scerni e Chieti, situate rispettivamente nella collina litoranea meridionale e centrale dell’Abruzzo. La località di Penne, situata nella collina interna, si è distinta dalle altre per la maggiore entità delle precipitazioni, per i valori più contenuti delle temperature medie, della sommatoria delle temperature attive, delle ore normali di caldo e dell’Indice di Huglin. In questo areale si sono riscontrate anche minori condizioni di siccità (Tab.1). Tab. 1 Statistiche descrittive degli indici climatici e bioclimatici. Collina litoranea meridionale Scerni Collina litoranea centrale Chieti Collina interna PenneINDICI CLIMATICI E BIOCLIMATICI media dev.st media dev.st media dev.st aprile-ottobre Temperatura media (°C) 19,9 0,8 20,1 0,7 19,6 0,8 Numero giorni Tmax >30°C 28,8 15,5 34,3 14,8 30,6 13,4 Precipitazioni totali totali (mm.) 378 127,7 385 122,0 477 115,4 Media escursioni termiche giornaliere (°C) 8,0 1,0 8,3 1,3 8,4 0,8 aprile-settembre Indice di Huglin 2364 187,2 2423 179,2 2322 190,3 Indice di Siccità (mm.) -120 44,1 -121 49,5 -85 44,7 Indice di Freschezza della notte (°C) 16,7 1,4 16,8 1,4 15,9 1,4 Ore normali di caldo 3038 159,1 3045 119,1 2941 144,4 Sommatoria temperature attive 1924 169,0 1972 140,9 1868 163,8 settembre Media escursioni termiche giornaliere (°C) 7,9 1,2 8,1 1,5 8,6 0,9 Percipitazioni totali (mm.) 59 40,9 61 38,9 68 42,8 L’analisi delle serie storiche delle date di inizio vendemmia della cv. Montepulciano, eseguita con l’approccio della regressione lineare semplice (Tab.2), ha portato a stimare un progressivo sensibile anticipo di questa operazione colturale, che nell’arco di 35 anni, si sarebbe attestato attorno a 16-18 giorni nella collina litoranea, valore del tutto analogo a quello calcolato per Loreto Aprutino, situato nella collina interna. 3 - 32 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 32 03/06/10 15:48
  33. 33. Gli effetti del cambiamento climatico sulle date di inizio vendemmia sono stati indagati ricorrendo nuovamente allo studio della regressione lineare semplice con gli indici climatici e bioclimatici già riportati in Tabella 1. Le date di inizio vendemmia sono risultate significativamente correlate, in tutti i tre areali, con le temperature medie del periodo aprile- ottobre, l’Indice di Huglin, la sommatoria delle temperature attive e le ore normali di caldo. I coefficienti angolari negativi evidenziano che all’aumento degli indici suddetti ha fatto riscontro un anticipo della data di inizio vendemmia (Tab.3). Tab. 2 Serie storiche di date di inizio vendemmia della cv. Montepulciano. Coefficienti angolari delle rette di regressione (β) e loro significatività.( ** = P0.01) Areale Periodo β Anticipo in giorni Collina litoranea meridionale (Scerni) 1974-2009 -0.52 ** 18 Collina litoranea centrale ( Vacri) 1974-2009 -0.46 ** 16 Collina interna (Loreto Aprutino 1977-2009 -0.56 ** 17 Tab. 3 Relazioni tra gli indici climatici e bioclimatici e le date di inizio vendemmia. Coefficienti angolari delle rette di regressione (β) e coefficienti di determinazione (R2 ). (ns = non significativo; * = P0.05; ** = P0.01),. Variabile Y (data inizio vendemmia) Collina litoranea meridionale Scerni Collina litoranea centrale Vacri Collina interna Loreto Aprutino Variabile X (indici climatici e bioclimatici) β R2 β R2 β R2 aprile-ottobre Temperatura media (°C) -5,73 ** 0,35 -5,40 ** 0,27 -6,64 ** 0,32 Numero giorni Tmax >30°C -0,12 ns 0,06 -0,21 * 0,16 -0,35 ** 0,22 Precipitazioni totali totali (mm.) 0,01 ns 0,02 0,02 * 0,12 0,03 * 0,17 Media escursioni termiche giornaliere (°C) 2,89 * 0,12 -1,69 ns 0,01 -1,10 ns 0,01 aprile-settembre Indice di Huglin -0,02 ** 0,22 -0,02 ** 0,30 -0,03 ** 0,27 Indice di Siccità (mm.) 0,04 ns 0,05 0,04 ns 0,07 0,07 ns 0,11 Indice di Freschezza della notte -1,47 ns 0,07 0,93 ns 0,03 1,24 ns 0,03 Ore normali di caldo (NHH) -0,04 ** 0,56 -0,03 ** 0,29 -0,03 ** 0,23 Sommatoria temperature attive -0,03 ** 0,36 -0,03 ** 0,29 -0,03 ** 0,31 settembre Media escursioni termiche giornaliere (°C) 2,97 ** 0,20 -1,15 ns 0.05 -0,45 ns 0,01 Percipitazioni totali (mm.) -0,03 ns 0,03 -0,02 ns 0,01 0,03 ns 0,01 ore normali di caldo (NHH) parziali Marzo-Aprile -0.04 ** 0.19 -0.04 ** 0.20 -0.05 ** 0.23 Marzo- Giugno -0.04 ** 0.45 -0.03 ** 0.39 -0.03 ** 0.30 Maggio-Giugno -0.05 ** 0.44 -0.06 ** 0.39 -0.05 ** 0.22 Luglio-Settembre -0.04 * 0.14 0.02 ns 0.03 0.06 ns 0.01 Da un esame approfondito della Tabella 3 emerge che la variabilità a carico delle date di inizio vendemmia sembra strettamente connessa alle variazioni stagionali riscontrate per le ore normali di caldo (NHH), come testimoniano i valori del coefficiente di determinazione R2 , che risultano superiori a quelli degli altri indici calcolati per i due siti della collina litoranea. Un ulteriore approfondimento del potere descrittivo delle NHH rispetto alle date di vendemmia ha riguardato la loro suddivisione in alcuni sottoperiodi dell’anno, perché, in base alla legge del minimo di Liebig, le risorse termiche possono rappresentare un fattore limitante soprattutto nei periodi in cui il loro livello è particolarmente basso o presenta elevata variabilità interannuale, come in primavera. Il restringimento del periodo di accumulo di NHH alla sola stagione primaverile 3 - 33 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 33 03/06/10 15:48
  34. 34. (periodo Marzo-Giugno) ha permesso di mantenere alto il coefficiente di determinazione, che è addirittura aumentato in due areali su tre. La variabilità temporale delle NHH per il periodo marzo – giugno è stata pertanto indagata allo scopo di individuare eventuali discontinuità attribuibili a cause climatiche. In tutte le zone si è registrata una buona corrispondenza tra i change point delle serie storiche delle date di inizio vendemmia e quelle delle ore normali di caldo del suddetto periodo (Fig. 2). Nella collina litoranea meridionale la data di inizio vendemmia è mediamente passata dal 28 settembre dell’arco temporale 1974-1991 al 18 settembre del periodo successivo. L’anticipo della vendemmia è parso connesso con l’aumento delle ore normali di caldo, salite da 1313 del periodo 1974-1997 a 1454 del periodo 1998-2009. Nella collina litoranea centrale la data di inizio vendemmia è stata progressivamente anticipata dal 9 ottobre dell’arco temporale 1974-1982, al 30 settembre del periodo 1983-1991, e al 24 settembre degli ultimi anni. In questo areale si è verificato un significativo incremento delle ore normali di caldo che sono salite da 1290 del periodo 1974-1984 a 1415 in quello successivo. Nella collina interna l’incremento delle ore normali di caldo e l’anticipo della data di inizio vendemmia si sono manifestati solo negli ultimi anni. Le ore normali di caldo sono passate da 1257 del periodo 1977-1998 a 1406 del periodo 1999-2009 mentre l’inizio della vendemmia è stato anticipato dal 14 ottobre dell’arco temporale 1977-2002 al 30 settembre degli ultimi anni. Fig. 2 Analisi del change point applicata alle ore normali di caldo del periodo marzo giugno e alle date di inizio vendemmia. Le linee tratteggiate verticali indicano i change points mentre le linee orizzontali poste in basso in ogni figura indicano l’intervallo di confidenza al 90%. Le linee spesse orizzontali rappresentano la media dei periodi. Conclusioni Fin dalla sua fondazione avvenuta nel 1816 ad opera di Alexander von Humboldt (Mariani, 2002), la climatologia si propone di individuare areali o periodi storici climaticamente omogenei , con lo scopo finale di fornire strumenti di supporto per le scelte gestionali. A tale approccio si ispira in 3 - 34 VIII INTERNATIONAL TERROIR CONGRESS Cra viticoltura_libro 1_capitolo 3.indd 34 03/06/10 15:48