UCI: Decline in carbon-eating vegetation will make it even harder for California to combat climate change

Climate change is causing plants to die off in Southern California. This image is from Anza-Borrego Desert Research Center.
Climate change is causing plant die-offs in Southern California, like at the Steele/Burnand Anza-Borrego Desert Research Center.
(Courtesy of Sicco Rood)

To reach its goal of carbon neutrality by 2045, California will need to partly depend on vegetation, which helps clear greenhouse gases from the atmosphere.

Reaching that milestone will become increasingly difficult if greenery continues to disappear at the hands of higher temperatures, wildfires and other climate-related threats, UC Irvine researchers say.

Losses in vegetation could cause up to a 16% decrease in the state’s natural carbon storage capacity, according to a recent paper by UC Irvine researchers.

Last month, the university also released a study that found that vegetation decreased by 35% in the region’s deserts from 1984 to 2017 — and 13% in the mountains.

Plants absorb and store carbon dioxide as part of photosynthesis, which is how vegetation produces sugars and starches from Co2 and water.

Shane Coffield, lead author and UCI doctoral candidate in Earth system science, said the state is relying on models that don’t take into account the high vegetation losses, and assume that land management is all that is needed.

“So part of the state’s carbon goals to achieve the neutrality by 2045 involves putting more carbon into the land,” Coffield said. “Currently, the land is a source of carbon, and we’ve had lots of droughts and wildfires that have killed trees and led to carbon being emitted to the atmosphere on average.

“But the state’s goal is to reverse that through better management practices to put more carbon into the vegetation and into the soil. And so what we’re finding is that the climate is going to continue kind of pushing in the wrong direction for that. By the end of the century, we’re finding losses on the order of 10 or 15%, whereas the state’s goals are to increase the land’s carbon stocks by about 4%.”

The researchers predict that the coastal areas of Central and Northern California, as well as the low- and mid-elevation mountains, are the most vulnerable to losing vegetation and the accompanying natural carbon storage capacity. Coastal redwoods and conifer trees will likely be hardest hit, the researchers found.

The state’s redwood forests rely on a fairly mild climate, so even temperature increases of a few degrees could drastically affect their survival.

Conifers at lower elevations are being replaced by oak woodlands, which are generally less dense, Coffield said.

This could mean less carbon will be absorbed.

“We suggest that management should be targeted at just trying to protect those existing carbon stocks, as opposed to maybe increasing them, which is kind of the goal,” Coffield said.

As part of the state’s effort to reach carbon neutrality, it aims to rely solely on clean energy by 2045.

UC Irvine professor James Randerson said there is more pressure to de-carbonize transportation, like converting to electric cars, because of diminished vegetation and other natural methods.

Randerson, who co-authored the paper, said Orange County can play a role in saving vegetation through making investments in fire management.

Experts are predicting another historically bad fire season. Last year’s was the worst in California history, with six of the state’s largest-ever fires. Orange County had its share — the Blue Ridge, Silverado and Bond fires.

In June alone, there were several brush fires near Newport Coast that required more than 100 firefighters to extinguish.

Coffield said any local action to reduce emissions will help.

“Maybe the take-home message is it’s going to be especially challenging to put carbon into the land ... it might make more sense to focus on ways that we can actually reduce our real emissions,” Coffield said.

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