I’m not sure if this qualifies as burying the lede (Napa Valley Grapegrowers look Beyond Hang Time), but the title and opening paragraphs of the article published today by Wine Business Monthy on the Hang Time Seminar at Copia last week certainly don’t reflect my main take away from the climate portion of the talk.
The first two paragraphs of the article report on old news; there is evidence that global warming has occurred over the last century and human activity is thought to be responsible. What a snoozer! The real story to emerge from the talks doesn’t come until the third paragraph:
But he and Dr. Deborah Elliott-Fisk also suggested that the impact on Napa Valley may not be catastrophic as the popular media suggest…
In fact, the weather in Napa Valley has been improving in some regards for at least 90 years. Dr. Snyder has analyzed records since 1917 from Napa and finds that January maximum temperatures haven’t changed much in 90 years, but the minimums have risen 5 degrees on average. Likewise, September’s maximums are up 6 degrees.
He feels similar changes should not be a big problem. “It’s the extremes that hurt you, not averages,” and Napa has actually had fewer extremes in the last few decades than in the past.
Likewise, flooding has declined from the past.
Now that’s news. It’s counter-intuitive and surprising. At least I thought so, and there’s even more to the story.
The slides from Dr. Snyder’s talk can be downloaded in Powerpoint format from the Napa Valey Wine Growers website if you’d like to have a look at his entire talk, or you can grab the slides as a pdf file right here from me (I prefer to store slides as pdf so I converted them). I’ll be highlighting a few of the sides here.
As the article mentions, Dr. Snyder’s main concern is that as a side effect of global warming Napa may experience an increasing number of extreme weather events in coming years. Yet, based on the data he presented, the risk of extreme high temperature events have been decreasing since the 50s, and pretty substantially since 1988.
As the peaks pictured above get higher in the middle, the distribution of temps becomes more tightly bunched and more uniform. I was surprised, given all the recent media attention, to find that this is an expected result. Outside of the tropics, scientists predict that extreme event variability should decrease given a warmer world.
And as you can see from the list of extreme temperature events for each month from the past
90 plus 89 years (doh!) years, only two are from 1990 or later, and none have occurred since the turn of the century.
What’s interesting is that the single biggest danger global warming poses for wine growers is that the incidence of these extreme weather events will increase, not that average temps will increase. San Pablo Bay protects Napa Valley from overheating quite well, and as temps increase Dr. Snyder predicted that fog due to evaporation from the bay will increase and stretch farther up the valley, insulating the grapes.
And given the fact that it is in nighttime temps that we are seeing the real effect of the temperature increase, what we have is a recipe for better grape growing conditions. Since grapes can continue to ripen at night when temperatures are relatively warm, global warming – paradoxically – might be just the thing to help out growers losing tonnage late in the season because phenological ripeness hasn’t kept pace with sugar accumulation.
So, global warming = no more long hang times! Can that be right?
Right or wrong, that’s the controversial headline I took away from the Beyond Hangtime seminar.
Now if only we can get some folks to come out and study the Russian River Valley as well. I could use some assurance that it’s not just the already-blessed folks in Napa that stand to benefit from this crazy global warming thing.