Last Friday’s San Francisco Chronicle had these two articles, both within one page of each other:

Cold summer not coldest

and

Scientists deem Earth’s warming ‘unmistakable’

How to account for such schizoid reports? According to the first article, although the summer of 2010 hasn’t set a record for cold, it’s been one of the chilliest and most persistently foggy in years, contrasting “sharply with record heat on the East Coast.”

According to the second article, “The past decade was the [world’s] warmest on record” and “Scientific evidence that the world is getting warmer is ‘unmistakable,’ according to…the National Oceanic and Atmospheric Administration.” So, despite the numbskull Tea Party allegations of “Climategate” and know-nothing denialism, the evidence “all point[s] to the same conclusion: Our planet is warming.”

I have written about the cold weather along the California coast for years now on this blog, but even before I started doing so, I was noting, in the vintage diary I keep every year for my reports in Wine Enthusiast, how chilly things have gotten since the notoriously hot summer and fall of 2004. The years 2005-2009, inclusive, all seemed colder to me than any I’d experienced since arriving here in 1978; and now, here we go again. I’ve written here how cold and wet our 2010 “spring” was — a “spring” that never happened until things warmed up, slightly, in June. Now here we are with July over, and both the average temperature and the number of sunny days in San Francisco are down. Here in Oakland, the average July high temperature has been running 2.1 degrees below historic norms.

As it is in San Francisco and Oakland, so it is in wine country. Yesterday (as I write; actually, last Thursday), somebody at Vine Cliff Winery, in Napa Valley, called to tell me “We’re 2-3 weeks behind” in average ripeness due to the chill, which leads naturally to concerns about Fall rains. A Sonoma winemaker wrote on my Facebook page, on July 20, “We’ve had something like 6 days the whole year when it has been over 90°…Our grapes are just barely pea-sized still and I’m think[ing] we could be a month or more behind. Wild.” As July is Sonoma town’s hottest month, on average, the temperature for the rest of the summer is likely to be even more moderate than it has been — a trend that will probably continue, according to the Chronicle article.

Even in the normally baking Central Valley, “There have been few, if any readings of 100 degrees this summer within 100 miles of the coast.” You have to get to practically Las Vegas to experience true, western-style summer heat.

I can’t explain these cooler summers and falls. A weatherman I know once suggested that greater warming in the interior west / Four Corners is creating a gigantic thermal low that sucks in maritime air from the chilly eastern Pacific, where water temperatures struggle to get out of the 50s. It is from these cold waters, of course, that the coast gets its fogs and cool temperatures, driven by prevailing winds from the west/northwest. Maybe that’s the explanation. All I know are two things: People from San Francisco to Los Angeles are grouchy because the summer has been so damned cold, and the winegrapes seem to be loving it. All we can do now is hope that the fall rains hold off until, oh, sometime in November.

It’s raining again here in cloudy, wet Oakland, as it is in most of California from the Central Coast northward. It seems like this has been a really rainy winter, and it doesn’t want to stop. Not that I’m complaining. Well, maybe I am, a little — but the most common phrase this year has been “We need the water.” And we do, “we” being not just us humans, who consume it in the form of melted snowpack from the High Sierra mostly, but also the grapevines. Several winemakers have told me over the last two weeks that, despite all the rain, they were wishing for one or two more storms. Well, they’re getting what they asked for.

The season started out rainy and never stopped. Oakland got a record 3.86 inches back last Oct. 13, the “storm from hell” that sparked the infamous question, “Did you pick before or after the rains?” (For the record, Napa got 3.65 inches in that storm, while 3.16 inches poured down on the Sonoma County Airport.) In November, things dried out, but December turned wickedly cold and wet, a trend that has lasted until now.

By the time April comes to Northern California, your mind and body are prepared for Spring. Every flowering tree is in full bloom, the wildflowers lend a riot of color to the fields and hills, the robins are back, and even the fruit flies make their first appearance of the season. (Where do they live during the winter?) April holds the promise of six months of warm, sunny weather; April is the threshold of Paradise.

But this April has been a cruel tease. We had a day or two in the high 70s. But here are random notes from my Vintage Diary:

April 4: Cold, wet and windy.
April 7: More very cold weather, very wet and rainy.
April 10: The month continues to be very cold and wet.
April 22: The rain continues. Very, very cold.
April 28: Two consecutive days of rain.

The Oakland Airport weather station has had 19.75 inches of rain since last July 1 through today, which is 115% of the normal rainfall, 17.11 inches. The average precipitation for the season (which runs from July 1-June 30 every year) is 22.94 inches, so even though it feels like it’s been raining forever, we’re more than three inches below average. But we still have May to get through, a tricky month; the average precipitation here in May is less than an inch, but last May was very rainy, especially in the North Coast. We had big storms the first week of May, 2009, with totals up to 5 inches, and June was no picnic. My local weatherman called June, 2009 “the coldest June in 15 years.”

I’ve been noting ever since 2005 that the weather here in coastal California seems cooler than normal. That seems to be continuing. It may be that the Great Interior Basin (around the Four Corners of Arizona, New Mexico, Utah, and Colorado) is heating up, as well as California’s Central Valley. That would create a lower pressure gradient that would suck in air from over the eastern Pacific, where the water temperature is always cold, cooling the coast before the air warmed up again on its way inland. Whatever the reason for our cooler weather along the coast, it’s good for the grapes and wine (unless you get hit by mold or rain or a frost). Cooler temps = longer hangtime = ripeness at lower brix = more flavor with lower alcohol. At least, that’s the theory.

Anyway the forecast for today is continued showers and even the possibility of thunderstorms. The longer range forecast calls for clearing and warmer after today. But Springtime in California, like I said, can be a tease.

The climate change deniers, bless their dumb little hearts, are getting lots of buzz lately, but I’ll side with the scientists, the majority of whom are absolutely sure that warming is occurring and that it’s getting dangerously too late to do anything about it.

The latest — as if we didn’t have enough evidence — comes from Stanford, where UPI is reporting that a team led by Noah Diffenbaugh “say they’ve determined global warming could significantly negatively impact U.S. wine and corn production.” (I’m not going to write here about corn except to say that I love it when it’s ripe in the summertime and will miss it if it goes away.) They go on to say that “global warming could reduce the current U.S. wine grape region by 81 percent by the end of the century” due to hotter and hotter days in wine country like California’s, which, in places like Napa Valley, is already pretty hot.

(Diffenbaugh presents his formal study today at an American Geophysical Union held in Moscone Center and I’m sure it will be widely reported.)

It’s not just that excessive heat could make even coastal valleys inappropriate for delicate varieties, like Pinot Noir and Chardonnay. A warming climate could upset the ecosystem in much more fundamental ways. Science Daily describes how, “if spring-like weather arrives earlier than usual, and flowers bloom and wither before the pollinators [like bees] appear,” then wines might not even produce fruit. Earlier, scientists had calculated that a rise of only 2-4 degrees Celsius in grape regions could cause “losses [to be] be as high as 40 percent by mid-century.” In a previous study, Diffenbaugh determined that temperatures “from the principal wine regions of California, Oregon and Washington” already have risen in recent years by nearly 1 degree Celsius, and that was before some of the hottest years on record were yet to come.

It’s been surmised for years that other areas of the United States and North America could become more amenable to fine wine (vitis vinifera) growing as California gets too hot. Diffenbaugh warned as early as 2006 that by the end of this century “wine growing areas will be largely limited to the Northeast, including parts of upstate New York and Long Island.” And, of course, it was reported just yesterday that “there are some places in the world, such as the English vineyards, which stand to benefit from warmer temperatures.”

I know that some people don’t like it when I get all political on this blog which is a wine blog not a political blog or a scientific blog. But can we agree that a topic like climate change isn’t just scientific or political but may potentially impact us all? The leaked emails from a week or so ago gave ammunition to the deniers but as The [San Francisco] Examiner reported 3 days ago, the conservative furor over the emails “is much ado about nothing” and “the evidence of global warming is overwhelming.” Since I’m unable to conduct my own research into climate change, and don’t have the time or technical expertise to wade through mountains of studies and data, I have to put my trust in something; and I choose to believe the credible scientists from around the world and in every agency of every country I’m aware of (including the U.N.) that climate change is upon us, and one of its manifestations will be increased warming — perhaps not everywhere, or all at once, but California seems to be at risk, which means winegrapes are too, and that worries me.