California redwoods threatened by climate change

February 16th, 2010

Old-growth redwoods in Redwood National Park. That insect-sized creature at the bottom of the frame is me; the height of the photo was cropped by over two-thirds and I couldn't even get the tops of the trees in the original shot.

With all the focus on buffoons like Donald Trump (lauded climatologist that he is) pointing to this winter’s nonstop snow storms as evidence that global warming isn’t real, I’d like to reiterate that what we’re really talking about here is climate change. In this sound bite–driven world, semantics matter; the term global warming, while it describes what is likely happening to our planet, doesn’t paint a clear enough picture of the more visible changes in weather patterns that may be occurring as a result.

Case in point: California’s ancient coastal redwoods may be threatened due to declining summer fog levels, according to a new report in the Proceedings of the National Academy of Sciences. In the study, fog levels were found to have diminished by nearly three hours a day over the last century, increasing the likelihood of drought stress and eventual loss of trees.

From Reuters:

“Fog prevents water loss from redwoods in summer, and is really important for both the tree and the forest,” biologist Todd Dawson of the University of California Berkeley said in a statement.

…Dawson and colleagues estimated the frequency of fog by looking at weather records, especially airport records dating back to 1951.

“Since 1901, the average number of hours of fog along the coast in summer has dropped from 56 percent to 42 percent, which is a loss of about three hours per day,” said Berkeley’s James Johnstone, who led the study.

The researchers aren’t certain if the cause is natural climate variations or human activity (they’ll be looking at that in a future study), but I think we can all agree that the loss of these trees would be absolutely devastating, not just to the organisms that are part of this unique ecosystem, but to humanity as a whole.

I had a chance to visit Redwood National Park in October, and at the risk of sounding hokey, it was one of the great experiences of my life. To walk for hours among the very trees that had been there since before Christ was born — had stood in this same place at the time the Incas built Machu Picchu, and when Mozart wrote his first symphony, and while John Adams signed the Declaration of Independence…well, there are no words to describe it. I get choked up even trying to write about it.

The bright side is that these trees are incredible survivors: Coastal redwoods (or their very close relatives) existed as far back as the time of the dinosaurs, and goodness knows the climate has undergone myriad changes since then. But with just 5 percent of the world’s ancient redwoods left standing, it remains to be seen whether there will be enough to withstand the climate change we may be facing in the years ahead. We can only hope.

–Jennifer Grayson