A New One Per Cent

About 3.7 million Americans live within a few feet of high tide and risk being hit by more frequent coastal flooding in coming decades because of the sea level rise caused by global warming, according to new research.

If the pace of the rise accelerates as much as expected, researchers found, coastal flooding at levels that were once exceedingly rare could become an every-few-years occurrence by the middle of this century.

Thus begins an important article in this morning’s New York Times summarizing new research on climate change and sea level rise as it will affect the United States.  The research is the work of Climate Central, a think tank in New Jersey focusing on both original  research and dissemination of the work of other climate scientists.  They have produced a very cool web page summarizing the results of this latest study that is worth taking a look at (I’ve embedded the map itself below – take a look).

Some highlights from the NY Times article:

By far the most vulnerable state is Florida, the new analysis found, with roughly half of the nation’s at-risk population living near the coast on the porous, low-lying limestone shelf that constitutes much of that state. But Louisiana, California, New York and New Jersey are also particularly vulnerable, researchers found, and virtually the entire American coastline is at some degree of risk.

“Sea level rise is like an invisible tsunami, building force while we do almost nothing,” said Benjamin H. Strauss, an author, with other scientists, of two new papers outlining the research. “We have a closing window of time to prevent the worst by preparing for higher seas.”…


The new research calculates the size of the population living within one meter, or 3.3 feet, of the mean high tide level, as estimated in a new tidal data set from the National Oceanic and Atmospheric Administration. In the lower 48 states, that zone contains 3.7 million people today, the papers estimate, a figure exceeding 1 percent of the nation’s population…

The land below the 3.3-foot line is expected to be permanently inundated someday, possibly as early as 2100, except in places where extensive fortifications are built to hold back the sea. One of the new papers calculates that long before inundation occurs, life will become more difficult in the low-lying zone because the rising sea will make big storm surges more likely.

A couple of brief comments to summarize:

The fortification idea highlighted above falls under what climate specialists call adaptation.  It goes almost without saying that it would be easier and cheaper to pursue mitigation – reducing the risk by slowing and reversing green house gas emissions now – than relying on adaptation to get us through.

Adaptations are possible:  the Dutch have been fortifying themselves against the sea for years, of course, and many cities have hurricane barriers in place against storm surge.   Singapore actually has a sea wall on the drawing board that would eventually surround the entire island.  But such projects are expensive and take a long time to build.  They require a large present investment against a future hazard, a concept that is rational (anyone out there have fire insurance?), conservative by definition, but apparently almost impossible to propose in the present political climate.

Finally, what is most noticeable about this report is that it only addresses the problem in the US.  That’s fine – the vulnerability of almost 4 million people in our own country should be noted with great concern.  But it pales when compared with the billions of people around the world in countries like Bangladesh (PDF download) who are more vulnerable and have less hope of any sort of meaningful adaption strategies.  17 million Bangladeshis would be affected by a 5 foot rise, but their country is virtually unfortifiable because of its flat geography – even if time and money were available.  For them mitigation is the only possible hope, and the window on meaningful reductions in emissions in time to avoid major effects is closing fast.

Take a look at the map below – and read the article.  Thoughts?