Sunday, March 29, 2015

Crossing a Threshold

I imagine that the farmers and ranchers who lived through the Dust Bowl felt like the world (at least as they knew it) was ending.  That's the thing about drought - you don't know you're in one until it's well underway, and you don't know when it will end until it's over.  All you know for sure is that the world is not behaving normally.  Or, to put it another way, "Climate is what you expect, weather is what you get." This quote is often attributed to Mark Twain, but I can't find evidence that he actually said it!

As we face a fourth year of drought in California, I feel like we've crossed some sort of climate threshold.  The world has changed, at least from where I can observe it.  Here's a partial list of the things that feel different to me:

  • We have almost no snow in the Sierra Nevada (Spanish for Snowy Mountains).  Many ski resorts - even some of the big ones - have closed early.  The latest snow survey reveals that our snow pack is just 8 percent of normal for this time of year - the lowest amount every recorded in the 65 years we've been doing snow surveys.  Since we rely on snow pack for storing much of the water we use in the hot, dry summer months (for irrigation, drinking water and environmental purposes), the lack of snow is of grave concern.
  • The winter weather we have had this year was concentrated into a handful of relatively extreme events, punctuated by extended dry periods. December 2014 was the wettest December we've experienced since moving to Auburn in 2001.  January 2015 was the driest January in history.
  • Speaking of extreme events, we've seen wildfires and dust storms on the east side of the Sierra Nevada this "winter."  I talked to a friend whose family has ranched on the east side of Sierra Valley (north of Truckee) for generations.  They had a sand storm in February that left 2-3 feet of sand piled up along their fencelines.  A February wildfire north of Bishop burned more than 7,000 acres and destroyed many homes in the small community of Swall Meadows.
  • I manage sheep and cattle grazing on annual rangelands in the Sierra foothills.  The vegetation is 30-45 days ahead of where it should be in late March.  Our annual grasses are already producing seedheads - and some are dying back.  The blue oaks and black oaks leafed out at least 30 days earlier than normal.  And since the vegetation is off schedule, so are many of the insects and animals that depend on rangelands.  The wild turkeys are already nesting.  We have leaf hoppers in our grasslands that we normally don't see until early summer.
  • Much of this is related to temperatures, I'm sure.  We've had temperatures in the high 70s and low 80s in March - it feels more like May!  The warm temperatures and early vegetation growth means that soil moisture is depleted - what little precipitation we received since the first of the year is gone.

And so at the risk of sounding slightly apocalyptic, it feels to me as if we've crossed some sort of climate threshold.  If our own activities as humans have changed the climate (and I believe that the scientific evidence supports this perspective), then it feels as if we have moved into a period of rapid change and profound uncertainty.  We have challenging days (and years) ahead of us, I'm afraid.

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