When I first published Brace for Impact, six years ago, I did not give climate change its own chapter. I thought it was a slow-moving threat multiplier, that would exacerbate the effects of more immediate damage done by by polluters, industrial agriculture, peak oil and the like. Boy, has that changed. The onslaughts of drought, heat, savage storms and sea level rise have accelerated beyond the expectations of scientists just a few years ago, and as we come around the turn to the home stretch, climate change is neck and neck with the various other existential threats to the industrial age. The finish line, of course, being the place where we are all finished.
Nowhere are these events conspiring to accelerate more than along the East Coast of the United States. Here, multiple feedback mechanisms — accelerators that were not even identified until recently — along with a geological trend not previously thought to be connected are vexing the Atlantic Ocean from all sides until all it wants to do is attack us.
On October 27, high tide at Charleston South Carolina ran 8.67 feet above mean low water, the highest tide since Hurricane Hugo came ashore there in 1989. And Savannah Georgia saw 10.43 feet. Two days later high-tide flooding reached into substantial areas around Boston Harbor. And all of these high tides occurred in perfect weather.
A number of factors have made the East Coast ground zero (or should we say water zero?) for sea level rise. Perhaps the biggest is the flood of cold, fresh water into the North Atlantic from the melting glaciers on Greenland, whose deterioration has been accelerated by a whole set of unanticipated feedback loops. By changing the salinity and temperature of a large chunk of the ocean, that meltwater has contributed to a slowing of the great rivers that circulate through the ocean, such as the Gulf Stream, and among other things moderate the climate of Europe. Another thing the Gulf Stream does, as it flows northward along our coast, is to whisk away water that otherwise tends to pile up against the shore, contributing to sea level rise.
Meanwhile, another circulatory change, this one in the equatorial Pacific Ocean, is having another effect. This one is seasonal. It is popularly known as El Nino, and is blamed for more bad things than Obama, but is in fact a normal, long-lived set of recurring circumstances that are as much effects as causes of atmospheric events. One of the ancillary events, that occur because of the changes in the Pacific collectively known as El Nino, are the setup of prevailing northeasterly winds over the Atlantic off America. As long as El Nino lasts, these winds help pile up sea water against the coast.
Add to this the fact that the land along much of the East Coast is sinking, a continuing geological reaction to the end of the last Ice Age. The massive weight of the glaciers inland has borne down the tectonic plate on which the continent rests, bulging upward the places along the margins of the glaciers. When the ice melted the inland areas started rebounding upward, the coastal areas began to sink back to there they had been. The process continues.
What has been called “nuisance” tidal flooding, or “blue sky” flooding, has increased between 300 and 900 percent in East Coast cities since the 1960s. And according to a new set of calculations from NOAA, this winter and spring it’s going to get a lot worse. So if you live on the East Coast, beware the tides of March.