Friday, October 16, 2009

How Does Climate Change Affect Grape Growing?

Yesterday was Blog Action Day for Climate, so I thought I’d add some much needed information on the impact of warmer weather on wine making to the debate. And there is much debate over this issue, even if the media is slow to recognize it.

Obviously changes in climate are of prime interest to wine makers and grape growers. The shifting of temperatures can have some impact on the growing cycle and even the choice of grape varieties best suited to these changes. Since there has actually been a gradual cooling over the past several years, no immediate changes need to be made, but what about long range plans?

We do have one historical example to draw upon, and that is found in the Medieval Warm Period (MWP) from approximately 900 AD to 1300 AD. The MWP was warmer than our warmest years in the late 20th century, so it provides a good basis of comparison. During that warming period grape growing and wine making was common in England, along with a longer growing season in France. The added warmth was also increasing the amount of rainfall. There was more rainfall in the Middle East including North Africa than can be observed now.

In fact, during this period the great cathedrals were being built, commerce and trade flourished, and fewer people died from extreme cold conditions, which historically are harder on humans than warmer periods. The enrichment of CO2 from the warmer weather would also benefit plants, crops, and vines. The higher concentration of CO2 is a result of warmer temperatures gradually heating the oceans which release more CO2 as a result.

Although the general circulation models (GCM) used in climate studies had predicted warmer temperatures, the observable record from weather balloons and satellite data suggests otherwise, casting doubt on the reliability of computer-generated projections. While there is much dispute over the amount of warming, what causes it, and how much warming we might see, the prospects for wine making and grape growing in the foreseeable future appear to be bright.

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