Yesterday I went on one of my usual runs along the levees on this side of San Francisco Bay. It coincidentally happened to be during one of the highest tides of the year.
So as I ran south along the levee, I could see over five miles of water to my left separated by a ten-foot drop on my right by a twenty-foot wide, old dirt levee. For much of my run, the top of the levee was only three feet above the tide. Ahead and to the right was Google's headquarters, built right alongside the Bay. I couldn't see it but I know that Intuit was next door, along with many other driving companies of the Internet, and tens of thousands of residents.
The great sage, Bjorn Lomborg, says climate change isn't that costly and not worth spending too much money fighting. I don't know if he's including the rebuilding of the entire San Francisco Bay levee system when he makes his calculations. He thinks the sea level rise will only be eight inches in a century, so I doubt it. I know, though, that Silicon Valley and its residents aren't going to roll the dice on that prediction.
I should acknowledge there are second and sometimes third levees in most places, but not everywhere, and they're just as old and often no higher. And the levee system would have to be rebuilt regardless, but not as soon, not as high, and not as strong. Climate change is imposing this cost.