17
Air-Vegetation Interface: An Example
of the Use of Historical Data on Grape
Harvests
Valérie Daux
Historical data provide clues, often precise, of climate phenomena experienced by societies. The example below
illustrates the scientific approach applied to records of grape
harvest dates in order to quantitatively estimate the evolution
of temperature in a region.
The vine is a hardy perennial Mediterranean plant, well
adapted to hot dry weather conditions. Temperature is a key
environmental factor which triggers its various phenological
stages. Buds appear when daytime temperatures reach at
least 10 °C for an extended period, usually in April. Flowering dates occur about two months later (usually June),
when the daily temperatures cumulatively reach a certain
threshold. The date of the onset of ripening, veraison (in
August), is dependent on the date of flowering and the
subsequent temperatures. Finally, the grape reaches maturity
about thirty days after veraison, most often in September.
Harvesting takes place when the grapes are perfectly ripe.
The time between veraison and harvesting is fairly constant;
it depends on the temperature, on the phytosanitary status of
the vineyard and the amount of rainfall. The time periods
given for the different phenological stages are approximate
and vary according to grape varieties and regions.
Harvest dates, since they depend mainly on the temperatures during the growth and maturation of the vine, can be
regarded as thermal indicators. Variations in harvest dates
over the past centuries reflect historical variations in spring
and summer temperatures.
Historical Series of Harvest Dates
In the Middle Ages, the official opening dates of harvest
were set by informed feudal decision. After the Revolution,
this tradition was theoretically abandoned; each owner could
commence the harvest at will. However, the use of an official
date was maintained in most parishes, for reasons of security
and public order. After 1791, it was the mayor, advised by
the vineyard owners, who fixed the date of the beginning of
the harvest. The actual date of harvesting could take place
some days after this date. The official and real dates of
harvesting have been recorded in different registers
depending on the place and time: these might be in monastic
records, chapters of canons, hospital records (such as those
from the Hospices de Beaune, Burgundy, France), municipal
registers or private records (by the vineyards). During the
‘Medieval Climate Optimum’ (around 10th to thirteenth
centuries), vineyards were planted at latitudes as far north as
the shores of the Baltic or the south of England. Conversely,
due to the cooling of the ‘Little Ice Age’ (from the 14th to
the nineteenth centuries), most northern vineyards collapsed,
and the vine growing season was shortened so much that the
harvests were difficult even in some southern vineyards.
The series of published harvest dates are mostly composite series constructed from multiple sets of dates from
different sites of the same vineyard. Ideally, the composite
series should be established from local series of harvesting
dates of the same grape variety, to avoid introducing bias
related to a phenology which may vary by grape variety. The
longest and most comprehensive series published to date is
that of the vineyards of Burgundy (Fig. 17.1). This is a
composite series constructed from data from multiple sites in
the Côtes de Beaune and perhaps also from the Côtes de
Dijon. The grapes harvested in that area since the fourteenth
century are mostly pinot noir and chardonnay.
Reconstruction of Spring-Summer
Temperatures Based on Grape Harvesting
Dates
Grape harvesting data from the twentieth century, from
different vineyards and varieties, were compared with
regional meteorological data (Daux et al. 2007).
V. Daux (&)
Laboratoire des Sciences du Climat et de l’Environnement,
LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, 91190
Gif-sur-Yvette, France
e-mail: valerie.daux@lsce.ipsl.fr
© Springer Nature Switzerland AG 2021
G. Ramstein et al. (eds.), Paleoclimatology, Frontiers in Earth Sciences,
https://doi.org/10.1007/978-3-030-24982-3_17
205
Air-Vegetation Interface: An Example
of the Use of Historical Data on Grape
Harvests
Valérie Daux
Historical data provide clues, often precise, of climate phenomena experienced by societies. The example below
illustrates the scientific approach applied to records of grape
harvest dates in order to quantitatively estimate the evolution
of temperature in a region.
The vine is a hardy perennial Mediterranean plant, well
adapted to hot dry weather conditions. Temperature is a key
environmental factor which triggers its various phenological
stages. Buds appear when daytime temperatures reach at
least 10 °C for an extended period, usually in April. Flowering dates occur about two months later (usually June),
when the daily temperatures cumulatively reach a certain
threshold. The date of the onset of ripening, veraison (in
August), is dependent on the date of flowering and the
subsequent temperatures. Finally, the grape reaches maturity
about thirty days after veraison, most often in September.
Harvesting takes place when the grapes are perfectly ripe.
The time between veraison and harvesting is fairly constant;
it depends on the temperature, on the phytosanitary status of
the vineyard and the amount of rainfall. The time periods
given for the different phenological stages are approximate
and vary according to grape varieties and regions.
Harvest dates, since they depend mainly on the temperatures during the growth and maturation of the vine, can be
regarded as thermal indicators. Variations in harvest dates
over the past centuries reflect historical variations in spring
and summer temperatures.
Historical Series of Harvest Dates
In the Middle Ages, the official opening dates of harvest
were set by informed feudal decision. After the Revolution,
this tradition was theoretically abandoned; each owner could
commence the harvest at will. However, the use of an official
date was maintained in most parishes, for reasons of security
and public order. After 1791, it was the mayor, advised by
the vineyard owners, who fixed the date of the beginning of
the harvest. The actual date of harvesting could take place
some days after this date. The official and real dates of
harvesting have been recorded in different registers
depending on the place and time: these might be in monastic
records, chapters of canons, hospital records (such as those
from the Hospices de Beaune, Burgundy, France), municipal
registers or private records (by the vineyards). During the
‘Medieval Climate Optimum’ (around 10th to thirteenth
centuries), vineyards were planted at latitudes as far north as
the shores of the Baltic or the south of England. Conversely,
due to the cooling of the ‘Little Ice Age’ (from the 14th to
the nineteenth centuries), most northern vineyards collapsed,
and the vine growing season was shortened so much that the
harvests were difficult even in some southern vineyards.
The series of published harvest dates are mostly composite series constructed from multiple sets of dates from
different sites of the same vineyard. Ideally, the composite
series should be established from local series of harvesting
dates of the same grape variety, to avoid introducing bias
related to a phenology which may vary by grape variety. The
longest and most comprehensive series published to date is
that of the vineyards of Burgundy (Fig. 17.1). This is a
composite series constructed from data from multiple sites in
the Côtes de Beaune and perhaps also from the Côtes de
Dijon. The grapes harvested in that area since the fourteenth
century are mostly pinot noir and chardonnay.
Reconstruction of Spring-Summer
Temperatures Based on Grape Harvesting
Dates
Grape harvesting data from the twentieth century, from
different vineyards and varieties, were compared with
regional meteorological data (Daux et al. 2007).
V. Daux (&)
Laboratoire des Sciences du Climat et de l’Environnement,
LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, 91190
Gif-sur-Yvette, France
e-mail: valerie.daux@lsce.ipsl.fr
© Springer Nature Switzerland AG 2021
G. Ramstein et al. (eds.), Paleoclimatology, Frontiers in Earth Sciences,
https://doi.org/10.1007/978-3-030-24982-3_17
205