When dealing with a problem as large and diffuse as anthropogenic climate change, many of us have a Rubicon to cross. As recently as five years ago, I had practicing engineers tell me that there was no way that our individual impacts could combine to affect a system as large as the Earth. The escalating frequency and power of destructive storms has changed the minds of many of those doubters.

For myself, I never doubted the science, but it was an abstraction until I observed the changes in the Oak Trees when I returned to Livermore in 2004 after being away for ten years. Persistent drought had reduced the level of the Del Valle reservoir by almost thirty feet. When I finally found the opportunity to hike the hills rising from its western shore, I was astonished and dismayed by the battered look of the oak trees. Flaking bark and fallen branches littered the trail, and the sturdy equanimity of forest was replaced by a beaten weariness. When flying into Oakland over the reservoir in the early evening, the rust-colored crowns were evidence that the ecosystem was facing the loss of its keystone species.

These observations were magnified when I visited the IONS retreat center in Petaluma. I had seen isolated instances of sudden oak death along the freeway, but the trees along the ridge around the retreat center were decimated by the scourge. The branches and leaves were coated with a choking fungus. Recent rains had brought new buds that twisted as they suffocated. I reached out to offer a compassionate touch, until a voice warned me that the contact would coat me in spores that would travel with me.

The death of the oak forests was not so visible in Southern California. The coastal ranges come right down to the shore north of Santa Barbara, which seemed to act as a barrier to the spread of the fungus. And the trees in the Thousand Oaks area often line waterways sustained by treatment facility discharges. Even so, my thrice-weekly runs along the Chesebro trails confronted me with evidence of trees in distress.

Other factors also brought me pain: all throughout the West, the native scrub is being wiped out by the European grasses that now sprout up in the aftermath of wildfires. Even on old growth hillsides, shrinking brush has left exposed ground that is overrun by verdant lawn after rains. Where water gathers on fields, the invaders are thick stands of mustard plant. The weeds last only long enough to choke out the native sprouts, then die off, leaving soil at the mercy of the wind. In many places, the chalky lime of the range peeks through under the burnt stems of the sage.

When I took up Bikram yoga to combat my chronic back pain, my contact with these realities lessened. Even moderate exercise causes me to perspire profusely, leaving me in a dehydrated condition that forces me to break posture early in class. So I have given up hiking to refine my posture and prana flow. The disconnection came to the fore when one of the other students remarked that it was nice to see the hills greening again. I had to hold my tongue – I had observed over the winter that the lime green of European grasses was spreading on the burnt ground.

But I had been hooked. As I walked back to my car this morning, I felt the call of the green world. It seemed to say, “Yes, it’s not the way it was. But it is new life. Come and see us!” So when I arrived home, I put on my hiking boots and headed up the trail.

To be confronted with a large Valley Oak that had shed its lowest limb in a recent storm. The wound, so evocative of a screaming face, shocked me into recollection of the frightening dark forest of the Witch of the East in the Wizard of Oz. The sight was leavened somewhat by the sunflowers propped up against the trunk. I stopped to place my hands against the deep bark, and willed the matriarch to live, but she was weary. It was time to let go. So I offered the hope that a new sprout would rise under her guidance to provide new expression.

I wish I could say that it was an isolated experience, but not a hundred yards up the trail I encountered another casualty. This friend had lost its crown, probably more than a year ago. The lower limbs were thick with brushy twigs, made bare by the winter weather. This determined manifestation of the will to survive was contradicted by the evidence in the bark of a tree that stretched its lowest branch across Chesebro from the far side. The pattern of bark discoloration suggested that it, too, would be diminished in the near future.

While the Valley Oaks seemed doomed, the Coastal Live Oak, less grand in their ambitions, seem still to thrive. They lose their limbs, but even hollowed out, they channel water through the cambrium, reaching up and out to paint the sky with green.

But as I strode away from the arroyo to cut my way home along the road, the future was painted in bright green. After the last wildfire roared up Chesebro Canyon in 2004, the forest service attempted to demark and maintain native species restoration plots. Often no more than ten feet on a side, the chicken wire was often lost in a sea of mustard plant, and while steadfastly maintained, the drought yet murdered the native plants that had evolved to survive the dry months of our Mediterranean climate. The future was obvious on the slope above the trail head: stunted oak saplings, ringed by white plastic tubes to protect them from the deer, evoked a military graveyard against the backdrop of the European grass that coated the slope in a hyperactive green.