Different wine grape varieties require different amounts of heat to mature. That heat is usually measured in degree days - the sum of the number of degrees over 50 •F on average for every day between April 1 and October 31, the typical growing season for grapes. The graph below allows you to select a grape growing county and then shows the number of degree days accumulated over the last century and a quarter along with a line of best fit for the county selected.
Find the equation of the line of best fit for each location.
Region I
(< 2500)
Chardonnay
Pinot Noir
Gewürztraminer
Riesling
Region II
(2500 - 3000)
Cabernet Sauvignon
Merlot
Sauvignon Blanc
Region III
(3000 - 3500)
Zinfandel
Barbera
Gamay
Region IV
(3500 - 4000)
Malvasia
Thompson Seedless
Region V
(> 4000)
Thompson Seedless
other table grapes
1) Explain specifically what the slopes and y-intercepts of the two graphs tell you about the changes that have occurred in the two counties over the last century and a quarter.
2) Cabernet Sauvignon grapes have historically been grown in the cooler regions of Napa County. What does the change in the average number of degree days in the county suggest for the future of this grape variety in the county? Do some research related to the price of Napa Cabernet wine compared to the Zone III varieties listed in the table and discuss the possible economic impact.
3) Do some research about the primary grape variety in three other regions. How might temperature change affect the wine culture and economy there?
Degree day accumulations based on monthly mean temperature data from PRISM Climate Group: Historical Past (1895-1980), (Corvallis, Oregon: Oregon State University, 2017), downloaded December 12, 2017.
Data related to grape cultivation regions from Albert Winkler, General Viticulture, (Berkeley: University of California Press, 1965).