The Bay Area, on the heels of a record-setting heat wave in the midst of an exceptionally dry year, must contend with another consequence of climate change ahead of wildfire season.
Matteo Garbelotto, an adjunct professor in UC Berkeley’s Department of Environmental Science, Policy and Management, told KCBS Radio’s Jeff Bell on Monday morning that “tens of thousands of trees” are dying off across Northern California.
His research indicated climate change is one of two significant causes.
"Trees are now growing in a situation where days are hotter, there's less fog," he said. "There's a lot of variation between dry years and wet years, and they're suffering. And on top of this, we have infectious microbes – fungi – that are taking advantage of the fact these trees are stressed and they're becoming very active killers."
Garbelotto published a study in April identifying two fungi found in dying Acacia trees throughout the region: Diaporthe foeniculina and Dothiorella viticola. Dying and dead trees can serve as "fuel," Garbelotto explained, in two ways.
Dead trees present an increased fire risk near homes and buildings and the fungi use dead Acacia trees to produce more spores. The lack of density between trees allows the fungi to move rapidly from one tree to another, Garbelotto said, "causing this massive die-off."
Clearing out dead trees should be the short-term focus.
"Not only do you do something good in terms of fire prevention, but you also do something good in terms of lowering the infection rate," Garbelotto said.
Habits will need to change over the long term, according to the professor. Garbelotto called on stopping the planting exotic trees, like the Acacia, that don’t naturally grow in the region, as well as to more diligently maintain woodland areas and ensure there’s space in between trees.
Additionally, he said that urgency is required to make timely policy changes. Garbelotto’s research indicated there was a minimum two-year lag between infection and disease expression, and he determined the timing of disease development in the trees he studied from last December through this February was consistent with a 2017 wave.
The professor said policymakers and the public need to be on the same page.
"I think we need a joint effort of everybody to deal with this unique situation that we have never faced before," he said. "All the data is telling us that climate change is here, it's strong, and in 20 (or) 30 years, California will look different in terms of trees that are growing."