California faces up to last of the summer wines

IN California, the grape harvest has arrived early. Among the vineyards of Ridge, high above the Napa Valley, winemaker Paul Draper instructed his team to begin picking on 17 August. It was four weeks ahead of schedule - the earliest in the winery’s 43-year history.

Ridge is not an isolated case. Across the state winemakers and vignerons are reacting to an unprecedented March heatwave in which temperatures soared to 83F (28C). For the first time there is talk of a major "shift" in wine growing seasons.

It took California little more than two generations to establish itself as one of the world’s most important producers of fine wine. Now, nearly 200 years after Franciscan Missionaries planted the first vineyards on the outskirts of Los Angeles there are ripples of concern that California’s lucrative fine wine industry might be coming to an end.

New research by scientists at Stanford University shows the California wine industry is doomed by the end of this century, with global warming causing increased heatwaves and disrupting irrigation.

In the first study to specifically forecast the impact of global warming on an American state, scientists from the Carnegie Institute’s department of global ecology in Stanford, the Union of Concerned Scientists, the National Centre for Atmospheric Research, predicted that California "cannot save itself".

Using computer projection models, Carnegie’s Christopher Field, who led the study, said that if California continues to consume energy and burn fossil fuels at its present rate, the summer temperature by 2100 will have increased by 10C.

Dr Field said: "What we found was that as soon as the warming began to get in the upper end of our projections, most of California that is currently producing what you might refer to as fine wine - the coastal area, Napa Valley and Sonoma - become impaired for wine quality."

Although California is a hot state, scorched by the sun, it is cooled by the ice-cold California Current that flows down the coast at around half a mile an hour. It is the sharply hilly region between California’s coast ranges which recreates the lush conditions of the great wine making regions found in France.

In the Spring Mountain District of the Napa Valley sits Cain Five vineyards. A blend of all five classical Bordeaux varieties, Cain Five has come to represent everything modern Californian fine wine has become. Retailing at 390 a case, it is collected around the world, rivalling the great French wines in terms of price and quality.

Christopher Howell, winemaker at Cain Five, said that he takes the problem of climate change, and especially global warming, "very seriously indeed".

Mr Howell said: "The reason winegrowers don’t talk more about this is that it seems that there is nothing that we can do. With a change of 10C, the Cain Five would become even more of a collector’s item than it already is. As we know it, the Cain Five could not exist. At the very least, the varieties would change; at the worst there would be no Cain Vineyard at all."

This is a sentiment echoed by Dr Field, who said that any increase in temperature would affect the near perfect growing season in these regions, severely impairing wine quality.

He said: "We were interested in the effects of summer time temperature on the quality of grape varieties used to make fine wine. We found that most high quality grape varieties need to mature through a long, slow summer. If the maturation is exceeded too much you get a very low quality wine."

Paul Draper, winemaker at Ridge Vineyards, agreed. Established in 1959, Ridge has grown into one of the state’s most revered wines. Mr Draper said that a rise of 10C would not be the end of Ridge as they lie in one of the cooler areas, but it would affect the style to the detriment of quality.

"A warmer climate would quite quickly translate into wines of poorer quality," he said. "Over-ripeness simply makes generic wine, quality wine needs a long growing season.

"I am worried about the issue, particularly as our government shows no interest in changing its energy consumption patterns."

Recent figures show that the Californian wine industry has grown 40 per cent in the last four years and is now worth an annual 25.3 billion to the state, providing 207,550 full-time jobs, with employment rising annually by 9 per cent. Recently, it was reported that California was challenging France as the UK’s second largest wine supplier.

But Dr Field’s findings suggest that California may be going through a "golden economic period", with the disruption of the winemaking industry damaging cash flow in the future. The Central Valley, the workhorse of the state, could be too hot to grow wine at all leaving the fine wine areas left to produce the bulk wine. In short the economic effects would be catastrophic.

In Napa Valley, home to Mondavi, Heitz and Sterling wineries, widely regarded as California’s finest wine growing region, a tonne of Cabernet Sauvignon grapes is typically worth over $4,000.

In Fresno, in the Central Valley, an area known for its bulk wine, a tonne of Cabernet Sauvignon grapes is worth only about $250.

John McLaren, the UK director of the California Wine Institute, said that one solution might be to shift production to the cooler slopes and experiment with different grape varieties.

He said: "If you were talking about a small region with one micro-climate then it would be concerning but in such a big state there are multiple micro-climates anyway.

"Vintners are exploring the cooler climate areas of California. Now if they were to rise by 5 or 6 degrees than what is planted there at the moment, white wine grapes such as Riesling and Sauvignon Blanc might be replaced with big, red wine grapes like Syrah and Grenache."

Yet given it takes on average 70 years for a vine to start producing the quality of yield needed for a fine wine it would mean that wine makers would have to start plantings in the next decade. It is, according to Dr Field, impractical to do so at present.

He said: "California has a variety of different micro-habitats and it maybe that the cooler north sides of the slopes are still appropriate for growing wine, but it is important to remember that many times the quality of the yield increases over many decades and it is not practical to just keep shifting your vineyards around every two decades when the climate changes." Climate change is not new or unique to California. Between 1950 and 1999, the average annual global temperature has risen by 1.26C. In traditionally cool regions, the increased temperature wrought by global warming has provided better ripening conditions and more consistency from one year to the next.

In the Rhine and Mosel areas of Germany, two grape-growing regions with cool climates, grape quality has improved in recent years. Southern England has also benefited, a thriving winemaking region, it now produces world class sparkling wine.

It is these factors that gives Christopher Howell at Cain Five a glimmer of hope to cling onto.

He said: "The good news is, that over recorded history, wine-growing seems to have continually succeeded throughout the Mediterranean Basin, Egypt, Greece, Rome, Spain, France and this, through several significant climate changes."