subscribe: Posts | Comments      Facebook      Email Steve

More inaccurate herd reporting on Napa climate change


I was glad to see, via Terry Hall, the Napa Valley Vintners issue this clarification of the true state of climate change in Napa Valley.

They had to, because there’s been some sensationalistic reporting on that topic, in publications that should know better, including Reuters, which said “the results of climate change could [push Napa] beyond the acceptable band of temperatures required for…high quality varieties,” and The Huffington Post, according to which “By 2040 Northern California might have 50% less land suitable for growing premium wine grapes due to climate change.”

They were reporting on a short abstract in an online journal, Environmental Research Letters, whose bullet point is “We find that the projected warming over this period results in the loss of suitable winegrape area throughout much of California, including most counties in the high-value North Coast and Central Coast regions.” Others who jumped on this and wrote scary predictions about Napa’s future included Stanford University, the Santa Rosa Press Democrat, and the Los Angeles Times.

Maybe it’s asking too much for publications to put scientific studies into context. Journalists have neither the time nor the skills to do so. Newspapers that used to have science reporters have laid them off (with the commendable exception of the San Francisco Chronicle’s David Perlman). It’s much easier to run an attention-grabbing headline (“Warmer temperatures threaten California vineyards” — the L.A. Times) then to do actual research.

That’s why Terry Hall’s press release from yesterday (read it, please; it’s not very long) is so welcome. Terry knows, as do I and many others, that Napa Valley is not getting hotter. Anyone who lives here knows that we’re now in the seventh year of a cooling cycle, which has been notably accentuated the last three vintages. I’ve written about this endlessly in this blog: how truly hotter temperatures far inland are sucking more, not less, chilly Pacific air over the coast, which includes Napa Valley. (Terry specifically said Napa “is not considered a coastal region,” but I would dispute that. Historically, it has been considered coastal, “coastal” being synonymous with fog, which Napa Valley rightly celebrates.)

Terry called Napa “the poster child for the potential results of climate change” and he’s exactly right. Patiently, he explains the results of the Napa Valley Vintners’ own five-year study. He points out that “the results [of climate change] will not necessarily be a blanket effect, as climate change is not a ‘one size fits all’ phenomenon.” So true. Would that all reporting would be so diligent about the facts.

The NVV Study did find a little bit of local warming “over recent decades,” namely an increase of 1-2 degrees F., but only in overnight temperatures between January and August. That may be true, but it may not be. Survey findings are only as accurate as the data that were inputted, and, as we all know from reading, say, The Winemaker’s Dance, temperature and climate studies are notoriously inaccurate, especially when they go back for decades, when readings were even more unreliable than they are now.

So next time you read some panicky article on how Napa will be too hot for anything except Algerian varieties, don’t worry. Just pop open a bottle of Cabernet and read something else.

  1. We’re still waiting for summer to come and the kids are headed back to school.

    The increase in Napa Valley overnight temps is almost entirely caused by the urban heat effect, the release of heat absorbed by buildings and asphalt due to the expansion of urban areas within the Napa Valley. The weather stations of record for NOAA and NASA are at the Napa Airport, Napa Hospital, St. Helena City Hall, and the Old Faithful Geyser in Calistoga. The industrial parks, Napa College expansion, shopping centers, and tree removal account for changes at the first three. The Calistoga station is the puzzler, though locating a weather station next to a geyser seems a bit foolish from the get go. But if you go to you will see that most weatherstation locations are chosen with more attention to convenience than scientific accuracy. This means you locate them in a parking lot next to a government building,and sometimes next to the hot air from the outside condenser unit of an airconditioner.

  2. With apologies to Steve, I am going to do something I should not do. I am going to shill for my own blog.

    Just two days ago, at, I wrote an editorial entitled “California Becomes France and France Becomes California” in which I explained the very possible results of global warming. It was obviously somewhat tongue in cheek, but I am glad to see that some Francophiles took it seriously. If you would like a look at the lighter side of climate change, give it a read.

    Sorry for the commercial. It was just too tempting.

  3. I can’t agree more with you, Steve, and with Terry. Climate change is creating colder summers for us in the north coast and probably for all of California. You don’t have to be a scientist, just a weather junkie, like so many growers and winemakers are. That big stationary high that is parked over the middle of the country draws down a stationary low from the gulf of Alaska to off the coast of Oregon. It pushes and the high pulls, more and thicker marine layer inland from the Pacific. We get more fog, it goes further inland and burns off later, if at all. I told all our growers after last years disastrous end of harvest to expect a third cold summer this year and here we are. We’re carrying less fruit, wanting to get it ripe sooner, probably to little result. We are in a pattern of warmer springs, colder summers and earlier rains. Napa Valley will be growing Pinot rather than Cabernet.

  4. Ian Johnson says:

    I certainly hope the feeling that climate change is marginal at best and won’t fundamentally change viticulture in Napa plays out to be true. I also hope that growers will consider strongly that growing grapes in Napa is likely to change as a result of climate change.
    I’m certainly not an expert on the subject but it seems that very small changes to the average low temperatures (growing season) have a broad impact on what can be grown successfully (when precipitation occurs, volume of precipitation as a function of time, soil erosion, changing maladies of the vine and their impact). If Dr Hans Schultz and Greg Jones are correct in their assessment of global climate change, then it warrants some planning on how to ease the effects through mitigation such as yields, canopy management, height of vines, row direction etc..
    I hope the backlash to the climate change discussion does not encourage too many growers to bury their heads in the sand. It’s simply better to be prepared for any outcome.
    Some good interviews on the subject are:
    UK Wine Show 95 Dr Hans Schultz Climate Change and Wine 3 Impact on Viticulture in Europe.

    UK Wine Show 94 Greg Jones Climate Change and Wine 2 Climatology.

  5. I don’t know about you but I am pretty fed up with media and interest group sensationalism of this topic. Sensationalism – as well as outright misrepresentation – of the subject politicizes the science and makes it impossible to pursue a reasoned policy response.

    Morton – I will take issue with your interpretation. I believe the urban heat effect should be ubiquitous – daytime, nighttime and year-round, not just overnight from January to August.

    I seems to me that the effect is more in line with the observed long-term increase in local ocean surface temperatures. Nighttime temps are most influenced by the marine layer push into the Valleys, and the temperature of that marine influence is tied to the water surface temperature.

    Steve – re: the observed cooling – as a grape farmer I can tell you in my experience there is no question is it happening. But as much as I object to the sensational headlines, what makes you think the current cooling is permanent?

    The heat bubble over much of the country may represent a westward and northward expansion of an annual phenomenon that used to be confined to the tropical Atlantic Ocean. What if it continues expanding west and north as years pass, perhaps converging with an increasingly strong El Nino? How many years might it take for that to happen?

  6. John Kelly, I couldn’t say the current cooling is permanent. But if the interior warming is here for a while (decades at least), and if the coastal cooling is related to the interior warming, then the coastal cooling is here for decades also.

  7. John Kelly…read …daytime difference 1.8 – 5.4 degrees F, night time as high as 22 degrees difference. This nighttime effect is well known and well documented.

    If climatologists were real scientists they would locate and maintain their instruments properly. Instead they fiddle with compromised data and “correct” it with their guess at what the surface temps should be if the stations were properly located. This is like proscribing a statin by testing someone for cholesterol then adding or subtracting to the result based on a doctor’s guess. Why even bother with the measurement, why not just guess?

    If you want real junk science read Jones paper where he confirms global warming by analyzing wine scores based on 100 point scoring. Intestingly, his global warming graph shows a hockey stick that coincides with Parker and the WS discovering high scores help sell subscriptions.

  8. A hockey stick? I always thought the shape looked like a forked tongue.

  9. According to the aforementioned Press Release (Napa Valley Vintner’s; February 3, 2011), “[e]stimates of temperature changes in the Napa region are hampered by local changes in exposure, buildings and paved areas around the longest existing weather stations. For example, the commonly used weather station at Napa State Hospital, with a record going back 100 years, is situated over an irrigated lawn next to a black top driveway and a building with a large window air conditioning unit, and the St. Helena weather station is mounted on the roof of the city fire station, but was moved three times in recent decades”.

    Not coincidentally, these are the only two weather stations in Napa Co. that exhibit a divergence from the historical averages; with data showing stationary highs and uptrending lows.

  10. Morton – I share your skepticism of the data collection. Our modeling should use only the highest quality data available. On land, the standardized stations that are part of the CIMMIS system represent one approach.

    However, data normalization is probably unavoidable – unless we choose to discard all historical data gathered with technologies that are no longer state-of-the-art.

    An example would be the ocean temperature data I referred to; the automated ARGO floats used today provide much more accurate and spatially comprehensive data than the thermometers that have been tossed over the sides of ships for centuries.

    Steve – my mostly rhetorical question is: will the expansion of the annual summer heat dome phenomenon continue to the point that it spans both coasts?

  11. 1) The cool summer pattern of 2011 is *not* related to a warmer interior; it is the result of a large-scale onshore flow of marine air caused by a large atmospheric low parked off the NW Coast.
    2) Morton once again has used the reemergence of this topic on the blog to trot out statements that are just flat out wrong. Climatologists have looked solely at stations that have remained rural and have seen warming signals as robust as the “corrected” data set. That hobby horse is getting worn out. Morton, check out the recent work by arch-denialist Steve Watts of Watts Up With That on temperature stations…
    3) One observer suggested we call what is going on “global weirding”–not all regions are predicted to warm to the same degree or, in some cases, at all. In Iberia and in the Alpine foothills of Italy, for example, warming is real and persistent.

  12. BTW, Steve, the temperature/climate stuff in The Winemaker’s Dance is an incorrect application of a model that ignores coastal effects–useful in Montana, very wrong in coastal northern California. And in the words of Casey Stengel, you can look it up.

  13. David – Did you read Watt’s post of August 16 regarding the recent UHI paper by Mishra and Lettenmaier? When he says… “So, if NCDC was already tinkering with the station data by adjusting trends, is the conclusion “…that most temperature‐related trends are attributable to regional climate change, rather than to local effects of urbanization” valid? Or is it simply an artifact of the mixing mishmash ”… does that sound like agreement to you?

    Seems like when you normalize data using another data set and then compare that normalized data to the data set you used to normalized it, you certainly should expect to see a positive correlation between the two.

  14. Steve, thanks for the great shout-out. I think the most important point for all to consider is that this topic is wildly complex and as you intimate, the sensationalizing or reducing to sound bites, does not help the conversation. It doesn’t help with the big picture which is what do we do as individuals, as businesses, as a country, or as a leader in the world to work on this critical topic.

    I term it “cocktail party conversation,” which fails to inform and where these headlines leave the reader with something to bloviate about…like someone noted that the basis for the original Jones study by Oregon Wine Commission which all of these other report are based on started with the premise that Napa Valley Cabernet was getting high scores so something must be wrong–ouye, not a great scientific protocol!

    More to work on, and thanks again for the thoughtful discussion…

  15. Great post but way off the mark, I mean my tried and true method works best – plant a goat horn full of yak dung at exactly midnight on the first day of Spring and dance backward around it (the cow horn) four times (prior to burying it exactly three feet from your oldest grape vine)… Then chant an incantation in ancient proto Indo-European asking the weather fairies to bless your (one’s) grapes; then (and this is important), mate with your spouse, significant other, partner, best friend (or all five if you please) directly above where you performed the “rite.” Then ask the Earth Goddess to bless your crop, life and liveliehood… And this would be just about as effective as trying to predict weather patterns and global warming…

  16. Richard – thanks for the laugh. A perfect way to start the day!

    Charlie’s “California becomes France…” is a little sensationalistic, in my opinion.

  17. I’ve seen reports about several global models on warming that predict that while some parts of the globe do get warmer, others may get cooler. These models show that California is one of those places that may very well get not only get cooler, but also wetter in the future. However, the only sure thing that is predictable about predictions, is that they are usually wrong.

  18. Donn Rutkoff says:

    Global warming (nee climate change) and bio-dynamics, the horn, the tides, the moon, make for wonderful dreams.

  19. Has anyone been outside? It’s mid August and we’re not through verasion. Can’t get my tomatoes to ripen. Warming???? it’s cooling!

  20. Regardless of the cause the one point that most people miss when talking about climate is that we have to be prepared for change. It is pure human fantasy to assume that the Earth today is some sort of steady state system that is supposed to remain exactly as it is. Ocean levels will change and coastlines along with it. Rain belts will shift (North Africa used to be the bread basket of the Roman Empire before the Sahara ate it) and glaciers will flow and retreat. Nearly all the ideas in the climate debate are built on the false supposition that the climate that supports the current geopolitical state is the norm. Let’s quit trying to find someone to blame and figure out how to deal with change that will come regardless of whose fault it is.

  21. Francesca – amen.

  22. Angelo Monello says:

    National Academy of Science also made an extensive study with similar results. This is science and not opinion. Temperature is recorded over 24 hours and 365 days, not what it feels like some afternoon at 3:00 pm. Napa is already too hot to be classified as a Premium Grape Growing region. For instance: the year around current Average Temperature for Paso Robles is 59F and Napa 63F.

  23. It is not the high but the low that is important. Lows kill bugs – critical to vineyard health (among other things).

    Just curious, where are the weather stations (24/7) and what are the scientific results created/monitored by independent for NVVA? (And the same for all West Coast vineyards).

  24. Angelo Monello says:

    The critical issue is the low… and the high – the temperature swings. Temperature swings in Napa have reduced considerably over the last few years, one of the results of warming. The Diurnal Temperature Range is one of the basic factors in determining a Premium Grape Growing area. For instance, in the Paso Robles region it averages an astonishing 50 degrees during the growing season, one on the greatest in the world.

  25. Hi, Francesca

    It’s more worser than that. They want to roll back the “geopolitical state” to the birthdate of meteorology (or prior), which happens to be the tail end of the LIA, the coldest decades in the current interglacial.

Leave a Reply


Recent Comments

Recent Posts