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Climate change is complicated

January 25, 2011

A paper came out a few days ago in the journal Science that explains that plants in California–contrary to what you might expect based on climate change predictions–have been shifting downhill. This paper got a lot of coverage already, so I’ll just quickly summarize it, and add a few thoughts.

The paper’s title basically explains it all anyway: “Changes in Climatic Water Balance Drive Downhill Shifts in Plant Species’ Optimum Elevations.” The authors, from University of Montana, University of Idaho, and UC Davis, surveyed plants roughly along the coast starting just north of Santa Barbara all the way up to Oregon, going inland as far as I-5, and then looping over to include the Klamath Mountains, then south again to include the Sierra (or you could say,  it’s a big upside-down “U” around the Central Valley). They found that plants are following precipitation downhill, rather than following temperatures uphill.

It’s a reminder that climate change doesn’t only affect temperature, and that looking on different levels, from a large, landscape-wide perspective down to a hillside, can result in different projections.

Even looking at temperature alone doesn’t necessarily predict uphill movement. On a small scale, in some places, it could actually get cooler lower down and warmer higher up, what’s referred to as an inversion. I’ve written about that before, about how it applies to pikas.

The paper is behind a paywall, though you can pay for one-off access to read it, if you’d like. I also recommend Knight Science Journalism Tracker’s take on it (really, I recommend his take on just about everything).

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2 Comments leave one →
  1. January 28, 2011 5:57 am

    Molly- In the Klamath Mountains I have been un-scientifically witnessing downslope migration of foxtail pine into new habitat opened up on the north-facing high elevation slopes. Habitat is opening up here because snow-pack is either melting faster or there is less of it (probably both).

    Another idea I have heard about this phenomenon is that, say in the Sierra Nevada, lower elevation habitat is opening up as sites become more xeric and as mesic species like willows die out, pines are moving downward into these sites which, as you say above, still foster cool pockets.


    • mollysamuel permalink
      February 3, 2011 10:44 am


      So sorry it took me a week to get back to your comment!

      I’m not in the mountains nearly often enough to observe plant migration myself–that’s so interesting that it’s something you’ve noticed. What about birds and mammals? Do you think they’ve followed the foxtail pines down?

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