The impact of climate change on wine production is becoming increasingly pronounced due to its lingering effects on the environment and the resulting repercussions it may possibly have. UCSB Bren School professor Lee Hannah and staff researcher Patrick Roehrdanz conducted the first-ever global analysis of the impact of climate change on wine production and conservation.

Understanding climate change and its potential impacts is critical to understanding viticulture — the science behind the cultivation of grapevines. The researchers chose to study wine grapes specifically for their sensitivity to climate; in the past, viticulture has been used as an indicator to measure climate change. Not only does climate change impact viticulture, it also brings up concerns regarding conservation conflicts in freshwater ecosystems and land use.

An increase in temperature has a profound effect on viticulture, with warm and dry summers and cool and wet winters being most preferable for growing wine grapes. However, prolonged high temperature can be detrimental to the quality of the grapes as well as the vine. High temperatures in growing season additionally bring forward the harvest date to an even hotter month, resulting in lower quality wine grapes. The resulting increase in evaporation due to a rise in temperatures reduces the soil moisture in the long term, with an estimated 20 to 30 percent in northern Europe and 30 to 50 percent in western Europe.

Consequently, the harvest dates between varieties may overlap due to the late varieties being more sensitive to warming, resulting in a compressed difference in quality among wine grapes. The rise in carbon dioxide has a significant effect on the fruit yield of vines in that its strong relationship with temperature offsets the fertilizer. Because carbon dioxide is utilized in photosynthesis, a rise in the chemical will lead to an increase in leaf area as well as its dry weight. The plants are not capable of adapting to the rise in carbon dioxide fast enough. In the short-term, the elevated carbon dioxide will increase the photosynthesis to water-use efficiency ratio, resulting in an initial benefit; however, long-term exposure will ultimately be detrimental to the quality of the fruit.

Such desirable climates result in high biodiversity, rendering them global hotspots. Sustaining vineyards requires the removal of native vegetation, plowing and fumigation of the soil. In response to the climate change, plants and animals are likely to change their habitat while wine suitability is simultaneously changing.

Current studies have shown that there has been a pattern of warming in the northern hemisphere during the past 20 years, but less pronounced in the southern hemisphere. Global circulation models, however, predict even greater warming for the northern hemisphere in the next 50 years, considerably altering the margins of suitability for grape growing as well as the distribution of varieties in Europe.

A way to compensate for such drastic climate change is to relocate the vineyards to cooler locations with lower latitudes and higher altitudes. As wine consumption gradually increases, the demand for high-quality grapes has become a pressing issue. The challenge is to maintain high productivity with minimal environmental damage.



A version of this article appeared on page 4 of April 23rd, 2013′s print edition of the Daily Nexus.