Global warming could hurt Cal Poly and other premium winegrowing regions of California in the next 30 years, said Noah Diffenbaugh, an assistant professor of environmental Earth system science at Stanford.
Diffenbaugh and other Stanford University climate scientists said by 2040, the amount of land suitable for growing wine grapes could shrink by 50 percent all because of global warming. The study appeared in the June edition of the Environmental Research Letters.
A slight shift in global temperatures, 1.8 degrees Fahrenheit, would affect the growing conditions of Napa, Santa Barbara, San Luis Obispo and other surrounding areas, Diffenbaugh said.
Keith Patterson, a wine and viticulture professor at Cal Poly, said while the slight increase in temperature might not mean much to the average person, it drastically affects grape production for wine.
“One to two degrees may not seem like much to you or me,” Patterson said. “But to grapes, it’s a big deal. It affects the whole ecosystem in which they grow.”
California is a prime location for growing wine with its ideal weather conditions. Most notably of which are San Luis Obispo, Santa Barbara and Napa with a combined yearly average temperature of 60 degrees Fahrenheit.
“These areas are perfect for grape growing because their mild climates have made them major sources of high-quality grapes, and because they represent both cool and warm growing conditions, having mild days and cool nights,” Diffenbaugh said.
With rising temperatures, however, those conditions could soon change, he said.
Patterson said climate is the main driving force of what goes into the decision-making process to produce certain grapes and wines.
Cal Poly grows pinot noir and chardonnay grapes, both of which are perfect for cool climate conditions, Patterson said. When the temperature rises, however, the grapes ripen at an accelerated rate.
“When grapes mature too quickly, they produce a wine with too much alcohol and not enough acid,” Patterson said. “Acids are what give wine that tart taste, and the alcohol helps to moderate the sourness. You want there to be an equal balance of both in the wine.”
Grapes can be grown in any climate, though some climates are better than others.
“The grapes in Fresno are not as good as the grapes we produce here,” Patterson said. “Their climate just really isn’t set up for it, it’s too warm.”
The hot temperatures in Fresno, a yearly average of 65 degrees Fahrenheit, make it difficult to produce high-quality grapes, he said. And extreme heat can be the enemy of good wine.
“Wine is an incredible substance, containing over 300 compounds,” Patterson said. “However, a slight change can affect everything. If the temperature alters the mix of even a single compound, that can make all the difference between a bottle that is worth $10 or $100.”
If compounds are manipulated, the taste, color and smell can be affected.
With temperatures scheduled to rise, some wineries are considering switching to grapes that are better suited for a warmer climate, Patterson said. But when vineyards have staked their reputations on certain wines, adapting to climate change is a tough sell.
“Our top selling wines are chardonnay and zinfandel,” said Ashlie Leslie of Sextant Wines, a local San Luis Obispo winery. “Obviously, if those wines were off the market, we’d take quite a hit.”
Cal Poly recently began growing a small patch of Spanish Tempranillo grapes, which are acclimatized to warmer weather. These grapes can be produced on a much larger scale. Much like Leslie, Patterson also said that it is more difficult to market new wines to buyers.
“It is almost impossible to change consumer taste,” Patterson said. “Most clients buy something they know they like, something that they are familiar with. The price is too steep for them to expand and pick a wine that they don’t like. Change comes slowly with swaying people towards trying other wines.”
Patterson said it takes an innovator to change how the consumer thinks.
“When the hip-hop crew got started, Cristal Champagne sales skyrocketed just because P. Diddy was drinking it in a music video,” he said. “It all has to do with marketing. We know we make good wine; we just need to market better and get people to expand their horizons.”
The next 30 years will set the stage for how the wine-growing industry needs to adapt, Diffenbaugh says. While there is an expectation for higher temperatures, it is impossible to know how things are going to play out.
“It’s risky for a grower to make decisions that consider climate change, because those decisions could be expensive and the climate may not change exactly as we expect,” he said. “But there’s also a risk in decisions that ignore global warming, because we’re finding that there are likely to be significant changes in the near future.”
While there is a lot of uncertainty, the best thing to do is prepare for all the possible scenarios, Patterson said.
“We are in uncharted territory. It is basically the great unknown as to what the future holds.”
This article was written by Tony Easton.