RACING AGAINST THE STORMS
As sea levels rise, more significant measures might be needed to save lives and property, expert says
For three weeks after Christmas, California was pounded with a series of nine atmospheric river storms. The drenching rains replenished reservoirs that had been seriously depleted during three years of severe drought.
But they also caused flooding from the Central Valley to Santa Barbara, triggering mudslides, sinkholes and power outages, and left 22 people dead. Along the coast, big waves ripped a 40-foot hole in the Capitola Wharf, destroyed facilities at Seacliff State Beeach, flooded homes, wrecked businesses and caused millions of dollars in erosion.
For the past 55 years, Gary Griggs, a distinguished professor of earth sciences at UC Santa Cruz, has studied big storms, sea level rise and California's changing coastline. UCSC's longest-serving professor, he is one of the nation's experts in the ways oceans reshape the land.
This conversation has been condensed and edited for clarity and length. Q We've always had big storms. Is climate change making them worse? A I think that's fair to say. It's really difficult to attribute any one event to climate change. But the more we see in terms of the size of storms, and the intensity of hurricanes, droughts and temperatures, the more difficult it is to say this is totally independent of that.
We do know that as the ocean gets warmer it evaporates more water. And warm air can hold more moisture. Q How much has the sea level risen and how high is it likely to go as temperatures continue to increase? A Over the last century in California, the ocean has
risen about 8 inches. We know sea level rise is accelerating: Over the last 10 years it has been rising at a rate of about 20 inches per century. We can project out to 2050 with some assurance and say it's going to be at least 1 foot, and maybe more. Getting out to 2100, estimates range from 3 feet to 10 feet. What's far more important are these extreme events like we had in early January. High tides and big waves at the same time lead to the greatest damage.
QWhat does that mean for future big atmospheric river storms?
AWe had really high winds and really big waves in these storms. If that's a trend for the future, we'll see incrementally more damage. Every extra 6 or 8 inches of sea level rise will bring the waves closer to the shoreline and wash up higher to extend the damage farther inland.
We tend to think of atmospheric rivers as rainfall. But we had some really big winds, so the waves were going up over the bluffs. Those waves had their origin 2,000 or 3,000 miles away. When they got to the shoreline, you could see the winds blowing them inland.
QWhat kinds of places and facilities around Northern California are most at risk from rising seas and the wetter atmospheric rivers that scientists expect?
AThere are two types of places — very lowlying areas like Stinson Beach, San Francisco Bay, Rio Del Mar or Capitola. They are literally on the sand. They are going to be influenced by higher sea levels and waves moving farther inland, and have more frequent flooding.
Second are bluffs and cliffs. The higher the sea level is, the closer those waves are breaking to the cliffs. I would expect cliff and bluff erosion rates to accelerate in the future.
QWhat can we do about it?
Position:
Sea level is rising. We can measure it. We know it's accelerating. So when do we decide we've got to do something?
We've moved apartments, we've moved houses back, we moved Highway 1 inland in Sonoma County at Gleason Beach and also down at San Simeon. At some point we are going to have to start moving more back. No property owner wants to talk about that. It's become a bit of a bone of contention.
In the long run, it's not just more armor. The Army Corps of Engineers loves to build stuff. They have proposed a wall around Charleston (South Carolina), a wall around Miami, a wall around Galveston (Texas), and parts of New York and New Jersey. What are we getting for that? Is this going to get us five more years or 10 more? At what point do we say we can't keep doing that?
QBut there are hundreds of billions of dollars of property in these places.
AAt the San Francisco airport, SFO's seawall is projected to last until 2085. That's a place you want to save as long as you can. But how high can you build a wall? I would say let's not build any more really expensive facilities — power plants, sewage plants or desalination plants — where we know they are going to be inundated in 30 or 40 years. We need to look further ahead.
What do we do? I think this is the biggest chal