Vintners in the Burgundy region of France have been tracking their harvests since the 14th century, and they know as well as anyone the importance of picking their grapes at just the right moment to produce the best possible glass of Pinot noir.
Now, a team of scientists has found a way to look at sea surface temperatures in the North Atlantic and pinpoint that optimal harvest date six months in advance.
“If you’re a decision-maker in Burgundy involved with the wine industry … you could look early during the year, you could see what kind of patterns we have with the sea surface temperature, what kind of winter we had, and you could prepare yourself for a timing of the harvest date end of August, beginning of September,” says Yves M. Tourre, a senior research scientist at Lamont-Doherty Earth Observatory. Tourre spends most of his time at work for Meteo-France, the French national meteorological service, in Toulouse.
A warmer temperature during the growing season — April to the end of August — means earlier harvest. A preceding colder winter means a late bud-breaking and a delayed harvest.
The study, published April 28 in Climate Research, added a note of caution: Tourre’s team, along with other experts, concluded that the combination of natural climate variability and human-induced global warming could force the Pinot noir grape, with a narrow climatic niche, to disappear, possibly replaced by other varieties, in some parts of Burgundy.
French vintners – like agricultural producers around the world – are increasingly wary of the effects of changing climate. According to a report from Agence France Press, experts at a conference earlier this year warned that the climate in Bordeaux, perhaps the country’s most famous wine region, will by 2050 no longer favor Cabernet and Merlot, the chief varietals of the region’s red wines.
Another study published May 5 in Science says that global warming has reduced crop yields in some countries and could have been a factor in food price increases in recent years. The same study, co-written by Wolfram Schlenker of Columbia’s Department of Economics and School of International and Public Affairs, noted some areas have shown small gains in production from temperature increases.
The French scientists, led by Tourre, studied temperature records for Western Europe dating back to the 17th century, and records of grape harvest dates that stretch back to 1370, maintained by monks and others who carried on the venerable tradition of winemaking. They also looked at well-known climate fluctuations over the Atlantic Ocean, such as the Atlantic Multi-Decadal Oscillation, which modulates the weather patterns in Western Europe.
Their study found a remarkably tight relationship between sea surface temperature trends, European climate and the timing of the grape harvest. Basically, changes in climate affect the amount of solar energy, percentage of water content in growing grapes, and consequently the optimal grape harvest date.
“Pinot noir is an amazing grape,” Tourre says. “The number of days between bud break and harvest is near 135 days.” He said the impact of natural climate variability is aside from any worries people may have about global climate change.
Climate shifts have already affected high-profile crops in other regions of the world. In Latin America, warmer temperatures and more intense and unpredictable rains – which some scientists have linked to global warming – have reduced coffee yields.
In Indonesia, heavy rains destroyed chili crops and caused the price of the hot peppers, a culinary staple, to spike to $10-11 per kilogram, making them more expensive than beef, the Canadian Press reported.
The Times of India noted that tea production in Assam – where 52 percent of the country’s tea is produced – dropped by 15 million kilograms, and it tasted weaker than the traditionally strong brew the area is known for. That and other changes in the harvests of various crops are attributed to more frequent extreme weather events, the news organization said.