The sun peeks in and out of the clouds over Charleston Slough on a crisp June morning. A dozen or so birdwatchers amble along a bayland trail, some tossing around bird jargon, others silent as they gaze through binoculars, their smiling mouths curved like the beaks of long-billed curlews. At a glance, the birds out on the lake look almost static—dark spots in the grey-green landscape. But through a good lens every ruffle of feathers, every delicate dip into the mud, is visible.
Framed by a binocular lens the life of birds looks almost like a separate reality, but science has shown that those birds and the people who watch them share one thing: an ecosystem threatened by global climate change. According to avian experts, birds not only share our ecosystem, but also serve as important indicators of its health. Scientists agree that whatever change happens, whether it’s habitat destruction or extreme weather events, it will manifest first in the environment’s most vulnerable species.
“When birds are showing sides of distress, when there’s a drop in the bird population, then it’s a red flag. It’s a danger signal that something's wrong with the ecosystem,” said Bob Powers, executive director of the Santa Clara Audubon Society, who has worked to educate people about the dangers faced by both birds and humans.
As for the birds on the Peninsula coast, the loss of their habitat could serve as one of the most significant precursors to human distress. According to a report, to 26 inches in the next 50 years, threatening infrastructure, homes and businesses in Silicon Valley such as Facebook, which recently moved into a building adjacent to . Before the waters would inundate the new campus, however, they would flood the tidal marsh that rings the Peninsula; it is the largest stretch of tidal marsh in the Western United States, and home to numerous bird species.
Humans vs. tidal marsh?
At Point Reyes Bird Observatory Conservation Science, scientists have modeled the effect of sea level rise on five tidal marsh birds: the clapper rail, black rail, common yellow wren, and john sparrow. Their research shows that the marshlands’ fate depends on two things: the amount of water in the marsh, and the availability of sediment, which allows the tidal land to accrete elevation and thus keep up with sea level rise.
Within the more pessimistic scenario modeled, in which sea level rises 1.65 meters by 2110 and little sediment is available, scientists predict a 150% decline in the populations of black rails, common yellow throats, song sparrows and marsh wrens. The clapper rail population would decline by 50%. In an optimistic scenario, in which the sea level rises .52 meters by 2110 and more sediment (sediment availability ranges from 25 to 300 mg/L) is available, scientists predict an increase of about 150% in the clapper rail population and up to 100% increase in the populations of common yellow throats and song sparrows.
Two scenarios are necessary to examine the situation with accuracy, ecologist Sam Veloz says, because the exact effects of sea level rise are extremely uncertain.
“There really just isn’t any way to assign a probability to what’s going to happen in the future. At this point our understanding of global climate dynamics and the physics involved is just limited,” Veloz said.
The data suggests that the worst-case scenario is increasingly likely. A report sponsored by the California Energy Commission and published July of this year says greenhouse gas emissions have exceeded the trajectories that the Intergovernmental Panel on Climate change predicted in 2007.
The University of California, Berkeley also predicts that sea levels will rise 55 to 130 centimeters above current levels by the end of the century, noting that if the past trend of decreasing sediment availability continues, 90 percent of high and mid marshland could decrease over the next century under high rates of sea level rise.
According to Veloz, protecting marshland has been found to offer a certain amount of flood protection to inland areas. In an area surrounded by healthy tidal marsh, he says, humans may be able to rely on the ecosystem itself to guard against sea level rise.
“If you promote and restore tidal marsh habitat you’re actually getting some of those same [flood protection] services while at the same time providing habitat for species, so it’s sort of more of a win-win situation,” he says. “We’re in the process of trying to quantify how much flood protection you actually get.”
Marshland also serves as a refuge for the endangered California clapper rail, which is a chicken-sized bird that used to be hunted and served in San Francisco restaurants. It is also a prime breeding spot for song sparrows and salt marsh yellowthroats. The shorebirds forage on invertebrates in the mudflats, and the estuary serves as an important migratory stop for waterfowl, according to the California Energy Commission report.
Finding a good balance between the needs of humans and wildlife is a major challenge for people who are making plans to restore this area, Veloz said. One method of protecting human habitat, for example, is the building of levees. But levees don’t always protect marshland. Levees can interfere with the periodic inundation that tidal marsh needs to bring in the sediment that helps the marsh keep pace with sea level rise. The California Energy Commission report confirms this dilemma, noting that levee construction in the 20th century resulted in a two to six percent reduction in wetland habitat.
“You can see it as a conflict between tidal marsh habitat for both birds and other species and the protection of things like human infrastructure,” Veloz says.
The bigger picture
PRBO scientist Nathaniel Seavy says he has seen strong evidence of climate change.
“There’s definitely a signal of climate change,” Seavy says. “We see changes that are consistent with our expectations and they tell us really that we need to pay attention to these changes that are happening out there in the environment around us.”
Songbirds in the Bay Area, for instance, have steadily grown in size over the last few decades, increasing in body mass at a rate of 0.04-0.112 percent per year, according to a study by PRBO. Since this trend contradicts previous studies that suggested that warming favors smaller bird sizes, scientists believe this trend of increasing body size may reflect an adaption to more frequent extreme weather events due to climate change, according to Seavy. Scientists at PRBO have also observed changes in the timing of bird migratory patterns, changes in the timing of Pacific seabird breeding, and variability in bird populations.
So what do these changes mean in the greater scheme of our ecosystem? According to Seavy, the answer could be impending disaster.
“One of the things we’re looking for is sort of early warning signs that we might be approaching some sort of threshold where the relatively small changes that we’re seeing in the climate are having large effects on the ecosystems that we have around us,” he says.
Powers describes birds as a bellwether species, noting that as a big, colorful species they are relatively easy to track and study, making them especially good indicators. Seavy warns, though, that these thresholds are notoriously difficult to detect, as thresholds by their definition involve events that occur very quickly. Before these rapid events sneak up on us, Seavy suggests that humans look at the data collected from bird populations and make careful decisions about climate change.
“I think one of the really exciting opportunities that we have is to look for management actions that provide for win-win solutions, that is, management actions that can decrease greenhouse gas emissions and at the same time prepare for climate change and sea level rise and those other challenges that we know are coming,” Seavy says.
Surrounded by shrubbery and located next to a concrete road, the San Francisquito Joint Powers Authority office appears firmly rooted on dry land. Its work, however, lies on the coast.
“We’re doing projects that are driven by the need for flood control from both the creek and from San Francisco bay,” SFJPA Executive Director Len Materman says. “They also include very significant ecosystem and recreation elements.”
In order to anticipate the worst flooding scenario, SFJPA is preparing for a 100 year flood event, which is the level of flooding with a one percent chance of being surpassed in 100 years. In the wake of rising sea level, says Palo Alto Council Member Pat Burt, these projects are necessary to protect Silicon Valley’s high tech companies and to keep residents from having to purchase flood insurance. However, the SFJPA also has specific ecological goals in mind, aiming to shirk the conflict described by Veloz between building levees and protecting marshland.
“We’re one of the first to try to design something for hundred year flood protection and at the same time to actually improve the natural habitat,” says Burt.
One project, from Highway 101 to the bay, involves moving a Palo Alto levee into the Palo Alto golf course in order to turn seven and a half acres of the course into marshland. According to Materman, the project will result in 18 acres of new marshland planted with vegetation specifically catering to endangered species, including the California clapper rail and black rail. The project also includes the realignment of San Francisquito Creek, which according to Materman was adjusted to a “ridiculous” 90 degree angle in the 1930s to align with agricultural lands and a new Palo Alto airport.
“What we’ll be doing for the first time in about 75 years is restoring a connection between the Palo Alto baylands and the creek and that’s important,” he says. “We intend it to be depositing sediment into the Palo Alto baylands.”
A separate project involves the building of levees on the inboard side of Ravenswoods Ponds, and the subsequent removal of levees from the other side of the ponds, leaving that area open to inundation from daily tides. This periodic inundation combined with increased sediment availability should help build up the tidal marsh, which in combination with levees will further mitigate the effect of flooding on human infrastructure.
Matterman says that the SFJPA recently received a state grant to work on the second project, which he hopes will begin soon. The Santa Clara Valley district board recently voted to put on the November ballot a measure to fund projects around Santa Clara Valley, including around $35 million dollars for projects related to San Francisquito Creek, according to Materman.
“It’s not a situation where you if do nothing the problem remains the same. It’s a situation where if you do nothing the situation gets worse,” Materman says.
An American white pelican skims a body of water, its yellow beak like a piece of sunshine against the murky shore. A snowy egret reveals it’s golden feet as it marches through the water. A trio of black skimmers gathers on a log, their bills red as cranberries.
“I got a night heron in the scope!” says an experienced bird watcher.
“Hey, I got it,” says a boy in a baseball cap, who stands barely taller than the scope itself.
After a couple hours at Charleston Slough, the bird watchers have settled into a slow pace, shed a few layers, and shared countless glances to the few available field guides. When they flock to the scope they smile at the precocious bird watcher, because he is one of them, just tinier. If she were there, Shani Kleinhaus, environmental advocate at the Santa Clara Audubon Society, might smile because she sees him as part of the solution to climate change. According to Kleinhaus, kids ought to be educated to play outside and to appreciate nature.
“I think it’s really important. People should have open spaces with habitat where they can play,” she says.
As promising as the 100-year flood plan may be, restoring tidal marsh will not save all birds, nor will it solve the problem of climate change for humans.
“What’s really complicated about [climate change] is what an increasing temperature means for the globe and it really means very different things from one place to another on the surface of the earth, so the response of ecosystems to climate change isn’t a one size fits all response,” Seavy says.
According to Kleinhaus, addressing climate change requires not just action, but a shift in attitude. She believes that humans ought not just to look at birds as indicators of their own situation, but that they ought to look at nature as something to be valued. Kleinhaus explains that as rising sea level encroaches on bird habitat from one side, human land development threatens birds from the other side. She notes that, ironically, some of this development includes the building of bike trails and solar power, built for the purpose of reducing greenhouse gases.
Kleinhaus advocates a fundamental shift in the way humans view conservation. As the Bay Area moves forward with its efforts to mitigate climate change, she warns that perhaps we ought to learn to simply do with less. Otherwise, we may run out of resources, alternative or otherwise, she says, because there is always a limit.
“It’s not do or don’t do, it’s where to do it and how to do it so that we let nature survive with us,” Kleinhaus. “The vulnerable species, those that are more likely to disappear with global climate change in the Bay Area; those are the things that really indicate our situation. It’s an indicator or precursor of what’s coming to us.”