Research, Science & environment

UC Berkeley leads new assessment of Bay Area climate impacts

For the first time, detailed assessments lay out the impact climate change is already having on specific areas of California, including the San Francisco Bay Area, and look at what's in store

California today issued its latest assessment of the many challenges the state faces from climate change — including wildfires like those still raging throughout the state – and highlighted for the first time the regional impacts with nine deep-dive reports spearheaded by University of California scientists.

Bay wetlands at sunset

Rising sea level is one of the challenges Bay Area cities will face as a result of global warming, according to a new climate impact assessment issued by the state of California and informed by UC Berkeley research.

Half of the 24 authors of the San Francisco Bay Area Summary Report are from UC Berkeley, and four others are from Lawrence Berkeley National Laboratory. The coordinating lead authors of the eight other regional reports are from UC Berkeley, UC San Diego, UC Davis, UCLA, UC Riverside, UC Merced and UC Santa Cruz.

Announced on the first day of a three-day California Adaptation Forum in Sacramento, the Fourth Climate Change Assessment summarizes the impacts already being experienced around the state, estimates how much worse it will get by the end of the century, highlights adaptation programs now planned or underway at the local and state level and lists actions that the state should take to lessen the human, environmental and financial costs.

“In talking to cities and counties about what they are doing to adapt to climate change, you hear a big need for staff and money, because the planning for adaptation has to happen mostly at the regional and local level,” said Bruce Riordan, program director of UC Berkeley’s Climate Readiness Institute and one of four lead authors of the Bay Area report. “Sacramento is a critical partner — they can provide resources and people and regulation, but much of the on-the-ground work is going to have to be done locally and regionally.”

While California has taken major action to rein in statewide carbon emissions, which drive greenhouse warming and climate change, he said, dedicated funding and clear guidance to help the cities and counties adapt to rising sea levels, hotter temperatures, unpredictable rainfall and drought and year-round wildfires are still lagging.

“We are hoping to use these reports to get the same kind of attention to adaptation,” Riordan said. “These problems are serious, they are here now, they are going to get worse sooner rather than later, and we need to accelerate our planning for them, which is going to take coordinated state, regional and local resources. People used to think that if you talked about adaptation, it was a sign you were giving up. We’re not.”

logo of 4th climate assessmentThe three earlier state climate change assessments were mainly compilations of technical reports by academic and state and federal researchers. The new assessment includes updated technical reports, but also nine regional reports, three topical reports – including one on the climate-change impacts on California Indian tribes – plus a statewide wrap-up.

The new assessment comes a few weeks before the Sept. 12-14 Global Climate Action Summit, which is expected to bring thousands of people to the Bay Area. Co-chaired by Gov. Jerry Brown, it is designed to celebrate emissions reductions already implemented around the world and serve as “a launchpad for deeper worldwide commitments and accelerated action from countries … that can put the globe on track to prevent dangerous climate change and realize the historic Paris Agreement.”

Bad and getting worse

The San Francisco Bay Area Summary Report bullets the effects of climate change that residents are already experiencing:

  • The area’s average annual maximum temperature has increased by 1.7°F since 1950;
  • Coastal fog is less frequent;
  • Sea level in the Bay has risen 8 inches in the last 100 years;
  • The 2012-2016 drought drove statewide moisture levels to the lowest in more than 1,000 years and left a snowpack lower than seen in 500 years;
  • The 2015-16 El Niño storms created waves with energy 50 percent larger than average, driving unprecedented beach erosion;
  • The area burned in “large-fire” years in the Bay Area has steadily increased over the past 80 years.

The 2012-2016 record low snowpack resulted in $2.1 billion in economic losses and 21,000 jobs lost in the agricultural and recreational sectors statewide and exacerbated an ongoing trend of groundwater overdraft, the report notes.

areas flooded by rising sea level in Bay Area

Many areas of the Bay Area will be inundated by a 16-inch rise in sea level (blue), which is much less than predicted for the future. These include the Oakland and San Francisco airports, as well as many highways, refineries and water treatment plants.

What’s in store for the future? Even warmer temperatures, no matter how much greenhouse gas emissions are reduced. More “boom and bust” rain cycles, with very wet and very dry years. More intense winter storms, even as the average Sierra Nevada snowpack is projected to decline by over 80 percent by the last part of the 21st century. Between 2½ and 10 feet of additional sea level rise by 2100.

This means more energy use as air conditioning becomes essential, even along the cooler coast; more health impacts from pollution and disease; airports, roads, railways and waste water treatment facilities inundated by rising seas; electrical grids and natural gas pipelines imperiled by flooding; and greater socioeconomic and health inequality.

For the environment, some evergreen forests will turn into chaparral scrub; animals may get out of sync with their environment, leading to population declines; flooding will endanger wetland life, while wildfires and heat will threaten upland birds, mammals and amphibians. The San Francisco Bay ecosystem, hemmed in by development, will have little room to adapt as beaches, marshes and mudflats disappear.

Despite the doom and gloom, however, the report calls out 15 projects already operating to address these threats around the Bay, and calls for more such projects in the future. One example is the Bay Area Regional Reliability Project, in which the area’s largest water agencies have joined forces to develop a regional solution to improve water supply reliability for over 6 million area residents and thousands of businesses and industries.

“California is a leader on emissions reduction. We need to lead on adaptation as well, to minimize impacts to biodiversity and people in the Bay Area, especially for frontline communities who will bear the brunt of these changes,” said David Ackerly, dean of the UC Berkeley College of Natural Resources and the report’s coordinating lead author.

‘There’s a lot we can do’

The North Coast Summary Report, spearheaded by coordinating lead author Theodore Grantham, a UC Berkeley cooperative extension specialist and adjunct professor of environmental science, policy and management, highlights similar challenges but more upbeat opportunities to adapt to climate change. The area is more suitable for “green infrastructure” projects to deal with rising sea level, for example.

“Because most of the north coast has relatively intact coastal ecosystems, there are unique opportunities to accommodate climate change impacts like sea level rise, for example by preserving or restoring marshlands as coastal buffers, or setting back levees and allowing the coastline to migrate inland, rather than relying on traditional approaches, such as building seawalls,” Grantham said.

The authors prefer to focus on such opportunities to adapt to the environmental changes while acknowledging that emissions reductions are key to forestall the worst consequences of climate change.

“The overall takeaway is that, even if the globe goes on a huge emissions reduction path – which we are not even close to at this point – we are still going have to adapt, because things are going to get hotter no matter what, and oceans are going to rise,” Riordan said. “People want to hear that there are things we can do and, yes, there is a lot we can do.”

Other UC Berkeley authors of the Bay Area assessment are Mark Stacey, Scott Moura, Kara Nelson and Jennifer Stokes-Draut of the Department of Civil and Environmental Engineering; Steven Beissinger, Gregory Biging and Whendee Silver of the Department of Environmental Science, Policy and Management; cooperative extension specialist Max Moritz; and John Radke and Paul Waddell of the College of Environmental Design. Their Berkeley Lab colleagues are Andrew Jones, Mary Ann Piette, Alan Rhoades and Michael Wehner.