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Napa doesn’t seem to be warming, despite some predictions


If the predictions in this just-released study are true, then Napa Valley will be too hot for fine winemaking in a generation or so. That being the case, today’s young bloggers, who hope to make money writing about wine someday, might find it in their interests to take up residence in Billings or Fort St. John, and focus on the budding wine industries of Montana and British Columbia.

I believe in climate change, but I do think that the term “global warming” is misleading. It doesn’t seem to be getting warmer everywhere. My own opinion, for what it’s worth, is that coastal California–which includes Napa and Sonoma–is getting cooler, at least in the summers, because the interior West is getting warmer, creating a vast thermal low pressure system that sucks in air from the west. And, as we all know, to our west is a large, cold body of water. The Sacramento Valley may be heating up, but our little coastal strip seems safe.

Indeed, the San Francisco Chronicle, citing meteorological analyses, reported in 2011 that “California’s coastal regions appear to be getting more rain and cold weather while inland areas such as Fresno are getting hotter.”

The reason? “If you have more warm days in the Central Valley, you are going to have a stronger sea breeze so you will cool off the coastal areas. That certainly does not contradict any of the models about global warming. This is what is to be expected.”

Is the eastern Pacific Ocean cooling or warming? I don’t know, but neither do climatologists. As far as I can determine, the cyclical effects of El Nino and La Nina are the biggest drivers of the ocean’s temperature. The former warms it, the latter cools it. At any rate, I don’t think anyone expects the eastern Pacific to warm up dramatically enough to impact California viticulture anytime soon.

  1. Steve,

    Interesting topic, and my comment is a bit off-topic from that.

    While Montana doesn’t have much of a wine industry (nearly all the grapes used in the Treasure State’s small number of wineries come from Washington’s Columbia Valley), British Columbia’s wine industry has been fascinating to watch for the better part of 20 years. In fact, an area in the southern Okanagan Valley known as the Black Sage Bench gets more heat units than Napa Valley. The big issue is it’s all packed into a 110-day growing season, which is pretty intense and more prone to fall frosts than Washington.

    I was speaking with one of the top winemakers in February, who pointed out that temperatures in the Okanagan Valley of British Columbia have actually dropped slightly in the past decade. I’ll leave it up to the scientists to decide what that means.

  2. A winemaker related this to me a few years ago and it does make perfect sense. How far that marine influence persists depends on geography. It would be interesting to know if there are any studies showing change in diurnal temperatures within the coastal growing regions based on the effects of GW. (Adam Lee?). Attending a traditional outdoor film series under the oaks in Rutherford always requires goose down as it gets into the low to mid fifty range in July.

  3. I am the proud recipient of two semi-frantic emails from my eastern-U. S. relatives, who saw the referenced report in the NYT complete with woeful predictions that CA would become a desert in a couple of generations.

    Clearly, the researchers behind the report and the NYT people who wrote about it have no idea, none, about how the coastal climate here works. Whether or not we make Fresno to Reading into Arizona, we are extremely unlikely to destroy the grape growing areas here that are strongly coastally influenced.

    Indeed, there is even a line of thinking that the Delta region of CA (Yolo, Sacramento, San Jaoquin and Stanislaus counties) could also become cooler as marine influences get stronger because of the heating up of the rest of the Central Valley.

    The climatologists do not know, and clearly we in the wine biz do not know either, but the dire warnings in the recent study seem very much contradicted by the way the climate actually works here along the coast.

  4. The lack of predicted warming in the Napa Valley is also being mirrored worldwide. Despite a sustained production of anthropogenic greenhouse gases, the mean global air temperature has not risen for the last fifteen years. At the end of March the global extent of sea ice was above the long-term average and higher than it was in March of 1980. Worldwide hurricane and cyclone activity is near a forty-year low. The failure of the dozens of climate models that predicted otherwise are under scrutiny, not by skeptics often maligned as “deniers”, but by the very scientists who created the models.

    There is no doubt however that humans have had a negative impact on climate and the environment. We have done worse things than burning fossil fuels. We are causing 2/3 of the earths landmass to desertify. And we can reverse it if we choose. Check out this TED talk.

  5. Carlos T says:

    Interesting, i like this kind of topic. To whom it may concern england is producing great sparkling (i guess most of you know about it). I have tasted some and i can testify they are extremely well produced. Give them more time and they will learn how to make much better wines. 15 years ago this idea was more than a delusion.

    Germania, good old Germania, is producing more and more reds (still light ones), but the “bodier” (if this word exists in english) stuff is up next.

  6. Kurt Niznik says:

    Don’t forget that after the ENSO cycle, a big influence on eastern Pacific ocean temperatures is the Pacific Decadal Oscillation. Right now we are in a “cool phase” in the eastern pacific. The projected influence is supposed to be cooler and drier weather for the pacific coast. The PDO cycles seem to run about 30 years.

  7. Other models suggest: warmer temperatures, more evaporation from the oceans, more energy in the atmosphere (leading to more frequent and more violent storm systems), thicker fog penetrating further inland, coastal glaciers expanding. Who know what will really happen, but I would not be buying vineyard land in Montana or Okanagan. Areas on the margins, already subject to extreme weather events, don’t seem like a good bet if the weather gets more unstable.

  8. I took a vineyard tour with a winery owner in Walla Walla last September, and had an interesting discussion of growing seasons and climate change concerning Washington wines. “Let’s face it,” he said. “It was too cold to grow good grapes in these parts 100 or even 50 years ago”. Global warming has made a thriving wine industry possible by minimizing hard winter freezes.

    What continued warming in the Columbia Valley in Washington will do to the wine industry may not be so favorable.

  9. Hey Steve,

    Despite all the noise, there is little evidence support long-term climate change in the Napa Valley. Here is a link to a recent NVV press release provides some good insight on the subject.

  10. Just curious as to whether you have any basis of scientific fact or research to support your opinion about the general rise or drop in temperature in Napa. Although it’s probably a stretch to assume it will turn to a desert wasteland, and be devoid of grapevines, it does seem like that study has a fair amount of sensible conclusions drawn from extensive research by nine scientists who know more than you or I.

  11. Mike, obviously I’m not a scientist. But I do read as much as I can on this topic, and I also talk to a lot of people.


  1. NEWS FETCH – April 11, 2013 | Wine Industry Insight - [...] Heimoff: Napa doesn’t seem to be warming, despite some predictions [...]

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