As I write this note at the beginning of March, we’re enjoying our sixth weekend in a row without rain, spanning a period that’s generally the height of the Bay Area’s rainy season. For those of us who work all week and like to play outside on the weekends, this is great . . . except that it hasn’t rained much during the week either. I enjoy the opportunity to hike and bike on my days off as much as anyone–and some of these recent weekend days have been spectacular–but I’m starting to worry.
As well I should. According to Jan Null of Golden Gate Weather Services, it is the seventh driest July-February period on record for San Francisco since 1849-1850 (when precipitation data was first collected here), and we’re at about 40 percent of average rainfall for the first eight months of the rainfall year (July 1-June 30).
My first concern is for the state’s water supply: There’s generally not enough to go around even in normal years, and in dry years both fish and farmers can suffer (though the leftover from last year’s higher-than-normal rainfall will apparently be sufficient to carry us through one dry year). Then there’s the increased likelihood of a long and devastating fire season, with the hit that implies for the state’s already stressed landscapes . . . and budget. And finally–more selfishly–there’s the likelihood of a poor wildflower season.
Last year, we groused early on because the frequent and abundant rains kept the wildflowers in hiding (and many of us indoors) through much of the spring. But then the flowers kept coming through May, June, and July; there were even “farewell-to-spring” clarkia in the Marin Headlands in August! But this year? Unless there’s a heavy dose of rain in March, we’ll probably be done with wildflowers and the hillsides will be brown by mid-May.
Aesthetics aside, years like this raise a question: Is this a sign of a “new normal” due to climate change? Or is it just part of an “old normal” variation between wet years and dry years? According to Null, meteorologists work with 30-year data sets to assess such trends. And the latest 30-year set (1981-2010) actually shows a very slight increase in precipitation over the previous set. So we can say that for now, at least, our climate is not getting drier overall.
This is consistent with climate change models for California, which don’t show major changes in overall precipitation, but do predict changes in the timing and nature of that precipitation, with an increase in extreme events, both storms and droughts. So perhaps the swing from last year’s deluge to this year’s drought is the new normal. Of course, this presents challenges for water system managers, but such issues should be amenable to careful planning and investment.
The challenge to our native plants, and the animals that depend on them, is another story, and one that we’ll be tracking in Bay Nature over the coming years. In the meantime, I’ll take guilty pleasure in the sunshine, while at the same time wishing for rain. And keeping my eyes out for those clarkia and hoping I won’t have to say “farewell to spring” too soon.