California’s famous coastline could become a thing of the past, according to a new study that predicts that up to 70% of the state’s beaches could disappear by the end of the century if measures aren’t taken to address rising sea levels and greenhouse emissions.

The study, conducted by researchers from the U.S. Geological Survey, says that the worst-case scenario could result in 25% to 70% of the state’s beaches completely eroding based on an analysis of satellite images and climate-change-driven sea-level rise models.

While the impact would change depending on each coastal area, the overall impact would be “grim,” according to the report.

For example, Half Moon Bay in Northern California could lose all of its sand.

In San Diego County, a one-meter rise in sea level would result in the area losing more than one-quarter of its coastal picnic areas, about half of its lifeguard towers and about 15% of its restrooms, according to the study.

The study’s lead author, Sean Vitousek, a researcher at the U.S. Geological Survey, has already seen the difference at his local beach in Santa Cruz, mainly spearheaded by California’s recent wet winter season.

“A lot of the beaches in the area were completely eroded during the storms, and some of them have started to recover a little bit as we get into more summertime conditions with smaller surf,” Vitousek said. “But still, we have seen big effects from the storm, like the Capitola Pier breaking in half during the storm.”

Vitousek, who frequently visits the beach with his children, also noted that sections of Westcliff Drive in Santa Cruz are still blocked off due to the massive storms.

The report, which is still being peer-reviewed for publication, follows up on a 2017 report which focused on coastal erosion in Southern California. The 2017 study came to a similar conclusion, with researchers finding that 31% to 67% of SoCal beaches could erode completely.

“I personally spend a lot of time at the beaches with my kids and I think we really want to keep these resources available for everybody to enjoy,” Vitousek said.

In 2017, Vitousek also stated that if California lost a significant amount of beaches, it would affect the tourism economy, infrastructure in the area and damage homes.

Some have encouraged cities to protect their coastal communities by building seawalls or depositing large rocks that can sustain rigorous waves.

However, other experts have advised against communities building seawalls since they can damage wildlife and are expensive to build, according to The Verge.

Seawalls can be used “when appropriate” and “in limited circumstances,” the California Coastal Commission said, though the agency noted that they are only a temporary fix and that “for every seawall, the public can lose a public beach, dunes, wetlands and other coastal resources.”

The CCC proposed several alternatives to seawalls that can be used in a variety of situations.

Sometimes, so-called “managed retreat,” moving structures away from the shore as nature takes its course, is the best long-term option.

In other cases “beach nourishment” (adding sand) and “living shorelines” (using rocks, plants and sand to create a shore that grows over time) would prove most successful, the CCC said.

Regardless, Vitousek has said that officials should continue to monitor California’s beaches to determine how they can be preserved and maintained.

“I think it’s really important just to try to plan what the potential solutions are to maintaining beaches and coastal infrastructure as best as possible,” Vitousek said. “And it’s a very difficult decision that I don’t think there’s a one size fits all solution method. But it’s really important to monitor and think about adaptation pathways and different options.”

Editor’s note: This story was updated to correct the California Coastal Commission’s views on adapting to sea level rise.