The first thing to go will be California's calling card: its beaches.
Between a third and two-thirds of Southern California beaches will succumb to sea-level rise by the end of this century unless global fossil fuel emissions are dramatically reined in, according to a 2017 U.S. Geological Survey report. They will be "completely eroded (up to existing coastal infrastructure or sea-cliffs)." Zuma, Redondo and Del Mar, among many others, could all but disappear.
As the beaches recede, California will lose a crucial economic driver. The state's last major free recreational area will vanish along with our defenses against coastal storms. Our regional identity will shift as we're forced to turn inland.
The inundation news gets worse. A state-commissioned 2009 report by Oakland's Pacific Institute found that in even a medium to medium-high emissions scenario, nearly half a million Californians, predominantly minorities and the poor, will be vulnerable to flooding by century's end.
Threatened infrastructure includes the nation's two busiest ports, Los Angeles and Long Beach, as well as the Port of Oakland; the San Francisco and Oakland airports; 3,500 miles of roads; 280 miles of railways; 30 power plants; 28 waste treatment plants; vast wetlands; and, perhaps most distressing, 330 U.S. Environmental Protection Agency-regulated Superfund and other hazardous waste sites.
Flooding at those sites could spread a toxic brew into groundwater and water bodies such as the San Francisco Bay, where many of the sites are located. The only way to ward off that prospect is to clean the sites now, but the Trump administration, apparently unconcerned, has proposed cutting Superfund program funding by a third.
Still not alarmed? Then consider that the pace of sea-level rise is accelerating. California has so far escaped the fate of Florida, where many communities are already experiencing chronic flooding, but our turn is coming. From 1880 to the present, the ocean has risen eight inches. Thanks to intensifying global warming, from now until 2100, the increase will be a matter of feet, not inches.
Until recently, climate scientists believed that sea-level rise for the rest of this century would amount to about 1 ½ feet if global greenhouse gas emissions were drastically cut, and 2 ½ feet if emissions stayed high. But an April 2017 report commissioned by two California state agencies concluded that under the low-emission scenario, the sea level would rise 2.4 feet, and under the high-emission scenario, it would rise somewhere between a catastrophic 3.48 feet and an Armageddon-ish 10 feet. At a 10-foot rise, the long list of affected communities includes Marina del Rey, Long Beach, Huntington Beach, Newport Beach-Balboa, San Diego and all municipalities bordering the San Francisco Bay.
On top of this, a December study in Nature that compared climate models with actual atmospheric changes found that the most dire climate projections have so far turned out to be the most accurate ones.
One reason that projections have grown more ominous is that scientists have concluded that glacial melt, the chief driver of sea-level rise until now, is likely to be supplanted by the more consequential melting of the Antarctic ice sheet. As the ice sheet melts, gravitational forces there will dissipate, allowing more water to spread out from the poles. Thanks to the Earth's rotation, this will have a particularly strong effect on California: For every foot of global sea-level rise caused by Antarctic melting, the state will experience a rise of about 1.25 feet, the report said.
If there is any consolation in all this, it's that the state has time to adapt.
Many of Southern California’s beaches, for example, could retain their width if they were allowed to expand inland, which is what would happen naturally if highways, buildings, sewer pipes and other artifacts of development weren’t in the way. Beach house owners and local governments will resist abandoning or relocating their structures, but if no action is taken, the beaches will shrivel and the property will get flooded out anyway.
The alternative to retreat along the coast — building sea walls, levees and bulkheads — is expensive, damaging to beaches and would require constant maintenance and updating.
The state's most notable misstep so far is Caltrans' failure to take sea-level rise into account in the design for the post-Loma Prieta earthquake eastern span of the San Francisco Bay Bridge. It was completed in 2013 at a cost of $6.5 billion. A report a year later by the Bay Area's Metropolitan Transportation Commission found that by 2100, the approach lanes from the East Bay would be permanently inundated.
State agencies are paying more attention to sea-level rise now, studying its likely effects as a prelude to devising appropriate adaptation policies. They have much more work to do, but they're way ahead of the federal government, whose head-in-the-sand approach is embodied in President Trump's executive order in August instructing federal agencies not to consider flood risk caused by sea-level rise when building with federal funds.
Although state and local governments are left with the task of dealing with the consequences of sea-level rise, policy changes at the national and international level are urgently needed to ultimately curb it. Contrary to Trump and his fossil-fuel-addled supporters, the only way to avert a cascade of catastrophes is to stop emitting greenhouse gases as quickly as possible.
Jacques Leslie is a contributing writer to Opinion.