The Bay Trail connecting Sausalito and Mill Valley is a bustling pathway where recreational bicyclists, bike commuters, and pedestrians all mix amidst the bayfront marsh scenery of the Bothin Marsh Open Space Preserve. Around thirty times per year, though, this scene looks dramatically different, as high tides flood the area with seawater, making the path impassable.
Experts say this demonstrates how vulnerable the path and marsh are to sea-level rise, and an ambitious new project is underway to re-engineer the pathway and help the marsh adapt to this future. On June 8, the team working on this “Evolving Shorelines” project announced a final design that moves the Bay Trail to follow the perimeter of the marsh, but the decision didn’t come easy.
Bay Trail realignment. Map: ESA/WRT
“It was evident that the multiuse path is our most-used park asset, and it’s extremely visible to the public,” said Veronica Pearson, ecological restoration planner with Marin County Parks and part of the One Tam team leading the project. “And we wanted to be very conscious about how we develop the plan for adaptation and keep the public in the loop.”
In partnership with Golden Gate National Parks Conservancy, the project team has sought community input and guidance from the start. Indeed, this stretch of the Bay Trail is so popular that addressing its vulnerability to sea-level rise makes a great launchpad for conversations about climate change adaptation and the role of tidal marsh ecosystems. These ecosystems not only provide habitat for wildlife, they also act as natural water-filtration systems between the land and Bay waters and sequester and store large amounts of carbon.
The rising Bay isn’t a concern for the distant future; experts project a foot of increase in Marin by 2030, producing flooding events around 220 days per year. The one-foot increase would submerge the mudflats and shift the high-tide line closer to the road and communities, subjecting businesses and homes along Shoreline Highway to frequent flooding. By the turn of the century, impacts will be far worse.
The project team plans to take on the most urgent adaptations first, such as resurfacing the Bay Trail to maintain functionality for recreation and transportation. Walking or biking along the trail today, one can already see the corrosive effects of flooding seawater evident in the trail’s pocked surface. Project leaders also plan to create raised marsh mounds and improve connectivity to tidal channels, which will not only preserve quality wildlife habitat but also help the marsh adapt to the shorter-term impacts of sea-level rise up to about two feet. Ultimately, however, planners seek to prepare for up to four feet of rise by 2060.
Predicted Sea Level Rise Impacts on Bothin Marsh. Source: ESA/WRT
Although the rich biodiversity of the marsh gives the feeling that it predates the human development surrounding it, the truth is that this area has undergone extensive changes over the last 150 years. In 1851, most of what is now marsh was actually open water. Significant engineering changes began in 1924 in order to support first a railroad bridge, and later a berm. The Bay Trail of today follows the footprint of this old railroad berm. This was followed by a 1960s flood-control project that rerouted Coyote Creek, impacting sediment supply to the marsh from the watershed.
All this engineering means that the natural processes that would sustain the marsh into the future aren’t in place, including a restoring flow of sediment needed to counteract erosive wave action. Despite these human impacts, the marsh habitat has become a vibrant habitat for wildlife and plants, offering views of acrobatic dives of Caspian terns alongside the more slow-moving elegance of Black-necked stilts as they forage in the mudflats.
Alternate Adaptation Concepts. Source: ESA/WRT
In October 2020, the project team presented three different trail alignment options to the public and explained related impacts to Coyote Creek. On June 8 of this year, following community input, the team announced the favored plan, which realigns the Bay Trail to follow the perimeter of the marsh. The design leaves the old trail embankment in place to create new, higher marsh habitat for wildlife and provides a buffer between the shoreline and waves coming from Richardson Bay.
A new raised embankment along the marsh perimeter offers higher ground for the trail, flanked by an ecotone slope (vegetated transitional habitat), as well as a buffer between the road and community and the high tides. Without the bisecting trail in the way, the plan allows the marsh to undergo a more natural adaptation process. The project is still in the planning and permitting stage, with implementation slated for 2025.
As excited as the project team is to tackle such a big challenge and test some of these adaptation techniques, Rob LaPorte, project manager with Golden Gate National Parks Conservancy, emphasized that we can’t miss the forest for the trees. “Slowing the pace of sea-level rise is critical to giving the marsh its best chance of survival: the slower the rate, the better opportunity the marsh will have to adapt. It’s a good reminder that climate mitigation and reducing carbon emissions are still our biggest tools to reducing impacts to our environment.”
Elyse writes about wildlife ecology and environmental science for Estuary. Her background as a wildlife biologist often leads her to stories about the joys of scientific discovery and the ways that people interact with, and about, the environment. She currently writes from a floating abode in the San Francisco Bay, where the neighbors occasionally nest on her roof. Some of her writing and photography can be found here.
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Hothouse Earth
By Ariel Rubissow Okamoto
Photo by Megan Nguyen
Nothing could be stranger than sitting in the dark with thousands of suits and heels, watching a parade of promises to decarbonize from companies and countries large and small, reeling from the beauties of big screen rainforests and indigenous necklaces, and getting all choked up.
It was day two of the September 2018 Global Climate Action Summit in San Francisco when I felt it.
At first I wondered if I was simply starstruck. Most of us labor away trying to fix one small corner of the planet or another without seeing the likes of Harrison Ford, Al Gore, Michael Bloomberg, Van Jones, Jerry Brown – or the ministers or mayors of dozens of cities and countries – in person, on stage and at times angry enough to spit. And between these luminaries a steady stream of CEOs, corporate sustainability officers, and pension fund managers promising percentages of renewables and profits in their portfolios dedicated to the climate cause by 2020-2050.
I tried to give every speaker my full attention: the young man of Vuntut Gwichin heritage from the edge of the Yukon’s Arctic National Wildlife Refuge who pleaded with us not to enter his sacred lands with our drills and dependencies; all the women – swathed in bright patterns and head-scarfs – who kept punching their hearts. “My uncle in Uganda would take 129 years to emit the same amount of carbon as an American would in one year,” said Oxfam’s Winnie Byanyima.
“Our janitors are shutting off the lights you leave on,” said Aida Cardenas, speaking about the frontline workers she trains, mostly immigrants, who are excited to be part of climate change solutions in their new country.
The men on the stage, strutting about in feathers and pinstripes, spoke of hopes and dreams, money and power. “The notion that you can either do good or do well is a myth we have to collectively bust,” said New Jersey Governor Phil Murphy whose state is investing heavily in offshore wind farms.
“Climate change isn’t just about risks, it’s about opportunities,” said Blackrock sustainable investment manager Brian Deese.
But it wasn’t all these fine speeches that started the butterflies. Halfway through the second day of testimonials, it was a slight white-haired woman wrapped in an azure pashmina that pricked my tears. One minute she was on the silver screen with Alec Baldwin and the next she taking a seat on stage. She talked about trees. How trees can solve 30% of our carbon reduction problem. How we have to stop whacking them back in the Amazon and start planting them everywhere else. I couldn’t help thinking of Dr. Seuss and his truffala trees. Jane Goodall, over 80, is as fierce as my Lorax. Or my daughter’s Avatar.
Analyzing my take home feeling from the event I realized it wasn’t the usual fear – killer storms, tidal waves, no food for my kids to eat on a half-baked planet – nor a newfound sense of hope – I’ve always thought nature will get along just fine without us. What I felt was relief. People were actually doing something. Doing a lot. And there was so much more we could do.
As we all pumped fists in the dark, as the presentations went on and on and on because so many people and businesses and countries wanted to STEP UP, I realized how swayed I had let myself be by the doomsday news mill.
“We must be like the river, “ said a boy from Bangladesh named Risalat Khan, who had noticed our Sierra watersheds from the plane. “We must cut through the mountain of obstacles. Let’s be the river!”
Or as Harrison Ford less poetically put it: “Let’s turn off our phones and roll up our sleeves and kick this monster’s ass.”
4th California Climate Change Assessment Blues
by Isaac Pearlman
Since California’s last state-led climate change assessment in 2012, the Golden State has experienced a litany of natural disasters. This includes four years of severe drought from 2012 to 2016, an almost non-existent Sierra Nevada snowpack in 2014-2015 costing $2.1 billion in economic losses, widespread Bay Area flooding from winter 2017 storms, and extremely large and damaging wildfires culminating with this year’s Mendocino Complex fire achieving the dubious distinction of the largest in state history. California’s most recent climate assessment, released August 27th, predicts that for the state and the Bay Area, we can expect even more in the future.
The California state government first began assessing climate impacts formally in 2006, due to an executive order by Governor Schwarzenegger. California’s latest iteration and its fourth overall, includes a dizzying array of 44 technical reports; three topical studies on climate justice, tribal and indigenous communities, and the coast and ocean; as well as nine region-specific analyses.
The results are alarming for our state’s future: an estimated four to five feet of sea level rise and loss of one to two-thirds of Southern California beaches by 2100, a 50 percent increase in wildfires over 25,000 acres, stronger and longer heat waves, and infrastructure like airports, wastewater treatment plants, rail and roadways increasingly likely to suffer flooding.
For the first time, California’s latest assessment dives into climate consequences on a regional level. Academics representing nine California regions spearheaded research and summarized the best available science on the variable heat, rain, flooding and extreme event consequences for their areas. For example, the highest local rate of sea level rise in the state is at the rapidly subsiding Humboldt Bay. In San Diego county, the most biodiverse in all of California, preserving its many fragile and endangered species is an urgent priority. Francesca Hopkins from UC Riverside found that the highest rate of childhood asthma in the state isn’t an urban smog-filled city but in the Imperial Valley, where toxic dust from Salton Sea disaster chokes communities – and will only become worse as higher temperatures and less water due to climate change dry and brittle the area.
According to the Bay Area Regional Report, since 1950 the Bay Area has already increased in temperature by 1.7 degrees Fahrenheit and local sea level is eight inches higher than it was one hundred years ago. Future climate will render the Bay Area less suitable for our evergreen redwood and fir forests, and more favorable for tolerant chaparral shrub land. The region’s seven million people and $750 billion economy (almost one-third of California’s total) is predicted to be increasingly beset by more “boom and bust” irregular wet and very dry years, punctuated by increasingly intense and damaging storms.
Unsurprisingly, according to the report the Bay Area’s intensifying housing and equity problems have a multiplier affect with climate change. As Bay Area housing spreads further north, south, and inland the result is higher transportation and energy needs for those with the fewest resources available to afford them; and acute disparity in climate vulnerability across Bay Area communities and populations.
“All Californians will likely endure more illness and be at greater risk of early death because of climate change,” bluntly states the statewide summary brochure for California’s climate assessment. “[However] vulnerable populations that already experience the greatest adverse health impacts will be disproportionately affected.”
“We’re much better at being reactive to a disaster than planning ahead,” said UC Berkeley professor and contributing author David Ackerly at a California Adaptation Forum panel in Sacramento on August 27th. “And it is vulnerable communities that suffer from those disasters. How much human suffering has to happen before it triggers the next round of activity?”
The assessment’s data is publicly available online at “Cal-adapt,” where Californians can explore projected impacts for their neighborhoods, towns, and regions.
The results are alarming for our state’s future: an estimated four to five feet of sea level rise and loss of one to two-thirds of Southern California beaches by 2100, a 50 percent increase in wildfires over 25,000 acres, stronger and longer heat waves, and infrastructure like airports, wastewater treatment plants, rail and roadways increasingly likely to suffer flooding.