Global warming in Napa Valley: Earliest bud break ever?

Bud break at Muir-Hanna in Napa Valley

With yet another warm February in California, many grapevines in Napa Valley awoke in the past week from a short nap and sent their first buds out into the world.

"Buds on Chardonnay have begun swelling and bursting on a few vines," Brittany Pederson, viticulturist at Silverado Farming Company said in a press release. "With this warm weather and no real rain or cold weather in the near forecast, it shouldn’t be long before everything takes off."

Matt Reid, winemaker at Benessere Vineyards, said, "I’d say we’re a good week to 10 days ahead of last year and about 17-21 days ahead of normal.”

In years past, farmers would fret about bud break so early because the young buds are vulnerable to frost. A single night with temperatures below freezing could be enough to damage an entire year's crop (though not the grapevine itself.)

But lately, frost seems a thing of the past. Global warming in California seems to have as much an impact on warming winters as in heating up summers. I don't know about you, but I spent much of February in t-shirts and shorts.

Not only that, there is no region in the world better prepared for frost that no longer comes than Napa Valley. When grapes are that valuable, it makes sense to buy equipment to protect them.

So what does early bud break mean for the eventual wines?



It could mean nothing at all. Mother Nature could still throw an adventure movie at Napa Valley. But let's say we get a new-normal vintage like 2012 to 2015.

If there's no frost, farmers are happy with early bud break. It moves up the whole schedule, which means early harvest, just in case California ever gets rain in autumn again.

Jennifer Putnam, CEO of Napa Valley Grapegrowers, told me an early bud break and early growing season allow farmers to distribute their vineyard work more evenly across the growing season. If the vines mature steadily, nobody's schedule is panicked or compressed.

Grapes should finish ripening earlier. This is a bit of a risk for wine quality, especially if you (like me) like your wines on the elegant side. Ideally, the grapes should reach full maturity during mild, not hot, conditions, so there aren't any rapid changes when winemakers are contemplating picking. If grapes that are normally picked in early October are instead ripe in early September, picking decisions might have a lot less leeway, as grapes can shoot up in sugar in a few days.

All this is really premature speculation, of course. But the earliest bud break ever: that's news. We now return you to your regularly scheduled political coverage of climate-change deniers.

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