These swaths of San Francisco could be underwater in just 70 years, extreme models suggest

Image 1 of / 33 Caption Close These swaths of San Francisco could be underwater in just 70 years, extreme models suggest 1 / 33 Back to Gallery

In 70 years, San Francisco as we know it could look drastically different under the most extreme sea level rise scenarios now being studied. Gentrification, development and the other forces of urban change we fret about may be mere trifles compared to the drastic effects of climate change, including the rise of sea levels and erosion, scientists say.

In the most extreme models, rising sea levels could displace more than 480,000 people along the California coast and result in property losses upwards of $100 billion if no preventative measures are taken, according to a 2009 study by the California Climate Change Center.

The study found populations in the San Francisco Bay Area are especially vulnerable, as are people of color and low-income communities. A later paper, published in 2018 by the American Association for the Advancement of Science, estimates between 48 and 166 square miles of the Bay Area will be underwater by 2100.

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The new, most extreme models could mean a 10-12 foot sea level rise that also includes the collapse of the Antarctic ice sheet, according to a Climate Central report released in April, 2017.

Using projections from Climate Central's Google Earth plug-in, based off data from the National Oceanic and Atmospheric Agency, SFGATE mapped out how San Francisco might look in 2100, if sea level rises to the worst end of the potential range.

The public can explore the tool directly here and see snapshots in the gallery at the top of this article.

Climate Change, an organization of scientists and journalists, does rate the extreme case as extremely unlikely, but possible. The group adds, "Under the extreme scenario, the sea would not stop rising that year. Rather, it would continue to add more than 1.5 feet per decade, and exceed 30 feet by 2200 for all coastal states."

The projections represent a worst-case scenario for San Francisco and represent how the landscape would look if there were no efforts to stave off the rising sea or to stem erosion. The sea level in California has already risen by 8 inches over the last century, a rate that will likely accelerate in the next century. Some models estimate the sea will rise by 4.60 feet in the next 100 years — nearly seven times the rate of the 20th century.

In San Francisco, tourist attractions like Fisherman's Wharf, Crissy Field and the Palace of Fine Arts will be lost to the sea, as will the Salesforce Tower, the Google offices, the San Francisco and Oakland Airports and the Ferry Building, according to the extreme Climate Central models.

Some of the city's wetlands and natural ecosystems will change or be destroyed altogether, and land not affected by sea level rise could be vulnerable to erosion — a process exacerbated by increased groundwater pumping throughout the state during the most recent drought. Arbuckle, a small town about 50 miles north of Sacramento, has sunk more than two feet in nine years, a recent survey by the California Department of Water found.

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You can view before and after images from current-day San Francisco and worst-case projections for the city in 2100 in the above gallery. It's worth noting, much of the land along the eastern coast of the city is made up of landfill.

It's not just landmarks the state stands to lose, but essential infrastructure. The California Climate Change Center provides exact numbers for the losses of critical infrastructure if a 100-year-flood event occurs in California. Across the state, these include:

Nearly 140 schools

34 police and fire stations

55 healthcare facilities

Approximately 3,500 miles of roads and highways

30 coastal power plants

28 wastewater treatment plants

Prevention measures can be taken, though they will be costly. According to the Climate Change Center, approximately 1,100 miles of new or modified protection structures are needed to stave off coastal flooding along the Pacific Coast. The California coast alone is about 840 miles long. The total cost of building or updating these structures is estimated at $14 billion, the Climate Change Center estimated, while annual maintenance would cost an additional $1.4 billion a year.

Editor's note: This story has been edited to further clarify that the maps illustrate potential flooding at the extreme end of projections.

Read Michelle Robertson's latest stories and send her news tips at mrobertson@sfchronicle.com.

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