To paraphrase Shakespeare, in the vineyards of the world, something worrisome this way comes. Over the last decade, global warming has started affecting those narrow zones best suited for growing wine grapes.
Warmer temperatures are a mixed blessing for winemakers. In colder climates like Bordeaux and Burgundy, more heat can increase sugars in the grapes.
Richard Snyder, a biometeorology specialist at the University of California, Davis, speaking at last year's Unified Wine & Grape Symposium, said a three degrees centigrade increase in temperature would create more carbon dioxide in the air, aiding photosynthesis and prolonging frost-free growing seasons.
The bad news, said Snyder, is that higher temperatures can bring more droughts to the Mediterranean and California.
Unlike so-called broad acre crops such as soybeans and wheat, wine grapes are a "niche crop that can only been grown in certain areas," says Gregory V. Jones, professor and research climatologist in the Department of Environmental Studies at Southern Oregon University.
"The issue today is, when we talk of global warming, we talk about humans' contribution, which is occurring at a much faster rate than in recorded history. What we used to consider a one-in-50-year drought is now more commonplace. The extreme heat of 2012 in the U.S. was a one-in-1,600- year event," he says.
Axel Heinz, director of production for Super Tuscan wine Ornellaia, said the prolonged European heat wave in the summer of 2003 was what alerted first producers to what was going on.
"The weather is now getting more and more extreme and unpredictable with sudden heat spikes, long lasting drought periods and violent and unpredictable rainfalls," he said.
Such spikes are forcing winemakers to adapt. Heinz has observed an accelerating trend of increased sugar levels leading to higher alcohol levels in the past five years.