Global warming in Napa Valley? Not so fast

Global warming in Napa Valley? Not so fast · Wine Enthusiast Magazine’s UnReserved with Steve Heimoff

Here’s the money quote in Jones’ and Goodrich’s paper: “…should the PDO return to a multi-decadal cold phase, wine growers in the Napa Valley and across the western USA will likely experience greater variability in wine quality.” [Italics mine]

I have noted on several occasions that the weather here in Northern California, at least on the coast, has been both anecdotally and objectively colder since 2005. This past Spring, we had the worst grape frost damage in 40 years. The average monthly high temperature in San Francisco was reported last month in the San Francisco Chronicle to have been below average for 17 months running, and we haven’t had massive heat waves during harvest since 2004. Jones and Goodrich write that “…these conditions have occurred during the 2007-08 winter and into spring 2008 where a much colder and wetter than normal winter in the PNW [Pacific North West] and northern California has been seen…boosted by the influence of the larger cold phase of the PDO in the North Pacific.” This is substantiated by the Jet Propulsion Laboratory at Cal Tech, whose website says “scientists think we have just entered the [PDO’s] ‘cool’ phase” that “is likely to last 20-30 years.”