As you raise a glass of decent red with your next Sunday roast, spare a thought for the carbon emissions required to cook the joint. When it comes to global warming, we all think of flooding arable land and saving the habitats of the polar bears and the penguins, because they are the stories churned out by the popular news machines. But spare a thought for the grape.

Stanford University have considered the grape in sufficient detail to publish a scientific article in Earth & Environment. They applied a computer model of climate change over the next three decades to four of North America’s premium wine producing counties in California, Oregon and Washington. The prediction assumes that there will be a 23% increase in greenhouse gases and that the average global temperature will rise by 1degree Celcius. Of course, all computer models based on assumption are prone to change. Data assumes a trend continues at a steady rate, and there is no allowance for single, unpedictable (even catastrophic) events.

Of the four counties selected, the most well known is Napa Valley, home of the cabernet sauvignon and pinot noir grapes. The current climate has historically had an average temperature of less than 20 degrees Celcius and fewer than 30 very hot days. The climate prediction not only increases the average temperature by one degree but also increases the number of very hot days to almost 40. The current land use in Napa would have to change as more than half of the existing land used for grapes would be unsuitable for the current varieties. Either grape production would have to move, or the variety of grape grown would have to change.

Grapes grown at the higher temperatures tend to provide lower quality wine, and therefore are of less value. Maintaining the quality of grape would mean moving vineyards to areas where the effects of global warming are likely to be less dramatic. So what are the grape growers and wine producers to do? Plan now while production is good and make a substantial financial investment to protect wine quality of the future, or gamble that the global warming predictions are wrong because they are only based on models that extrapolate a trend thus far. Maybe it is time to lay down the favorite pinot noir now – just in case.