Will rising sea levels affect me?

Dear Dr. Rock,

I heard recently that with global warming, many coastal cities will one day be underwater. Is this true? Is San Diego, where I live, one of those cities? Which cities will "go under" first? Is this something that might happen in the next decade or so? Or how long?

Doug Montigale

San Diego

Doug,
I don't want to get mired in the politics of climate change. It is a topic we need to think seriously about. Sea level change due to global warming is real, though perhaps not the most critical effect (that might be weather: drought, crop failure, drinking water...). But let's attend to Doug's question.This is not, strictly speaking, a geology question, since the science of climate change is multidisciplinary. I was just looking at the new National Geographic's article titled "Rising Seas" down at the barber shop. It has a fold out map [web version here] showing sea level if ALL the world's ice melted and sea level consequently rose 216 feet*. No one is saying that climate change is going to cause that. That would be bad, but it has happened in the geologic past, when the earth was much warmer during the Eocene, first instance, and glaciers were very rare or nonexistent on Earth.
Observations show that sea level has been rising since at least 1880. Between 1901 and 2010, global sea levels rose by 19 centimeters (7.6 inches) - an average of about 1.7 millimeters (1/14 inch) per year. But looking at the last few decades, it's clear sea level rise is speeding up. Between 1993 and 2010, sea levels rose by 3.2 mm (1/8 inch) per year - nearly twice the long term average.**
Small potatoes, huh? Yeah, but that is 1 inch every 8 years, one foot in less than 100 years. Still small potatoes? That doesn't account for any increase in the newly measured 1/8 inch rate. Current projections by the National Oceanic and Atmospheric Administration (NOAA) call for sea level rise of about 6 feet globally if carbon emissions are not drastically curtailed.

The view from my deck on a sunny day in Bellingham,
WA, USA. Elevation 133 feet above the bay. Alaska
Ferry terminal in the middle ground. Click to enlarge.

What does that mean? Is San Diego going to "go under" as Doug puts it? Well, no, only those places that are less than 6 feet above sea level, and certainly not in the next decade. The Silver Strand, with the North Island Naval Air Station, is going to be submerged, or at least very precarious. In my town, Bellingham Washington, on the Salish Sea, that means that the Alaska Ferry dock will need to be repositioned, the city's waterfront parks will be submerged, the busy marina on the bay will need to replace pilings and add to the breakwater. The former site of the Georgia Pacific paper mill on the waterfront, currently being redeveloped by the city and port, will need to be designed to have a higher level grade (elevation of sea level) than at present. Bellingham is a small city. Multiply that by every coastal city in America, and you are looking at big bucks. Studies show that New York City has assets of 2+ trillion dollars at risk. Miami is worse: $3 trillion. Hurricane Sandy nearly a year ago was pretty bad. Add 6 feet to that storm surge! Then extend that to the rest of the world. Read the National Geographic article for more data and the human story. Here is a University of Arizona website with detailed maps of some coastal US cities under various sea level increases. Read a pre-Sandy New York Times article (March 13, 2012) on the expected effects of sea level rise in the near future on Americans.


University of Arizona sea level forecast map for SE USA. Click to enlarge

The principal contribution of geologists to climate change theory is showing that the geological record (that  is, rocks) demonstrate that climate change has happened in the past. Evidence for climate change is preserved in a wide range of geological settings, including marine and lake sediments, ice sheets, fossil corals, stalagmites and fossil tree rings. Nearly all the world's geological societies, which represent most professional geologists, have issued statements of concern (at the mildest) or warnings that continued carbon emissions will only increase the threat from global warming.

* That would be the pits. My home, on a hill with a nice view of Bellingham Bay, seems far above the bay at an elevation of 133 feet. Hard to imagine my lot could some day be under 83 feet of water! Even worse, those snooty neighbors a couple blocks up the street would have waterfront property! I can only hope their boat's anchor fouls on my chimney.
 **The source for my information is an analysis of the 2013 IPCC report posted on the The Carbon Brief Blog. The report is based on observations, so the data is not 'wrong'. If you don't believe in the global warming theory, fine, but you can't refute the observed data. In the immortal words of Daniel Patrick Moynihan (US Senator 1927-2003), "Everyone is entitled to his own opinion, but not his own facts."