And here is the irony: Scientists can predict that Cape Cod is going to wash away in about 5,000 years, that the Cape will lose about a thousand acres to erosion in 200 years, and when we should expect a hundred-year storm, but they can’t tell a homeowner if he can stay in his barrier beach camp for another season or if it makes sense to build a seawall to protect his oceanfront house for another 20 years.
This is because erosion doesn’t proceed in a nice linear fashion according to sea level rise. The pattern is different: seven-year stretches of severe erosion follow seven-year stretches of mild erosion. And we saw this global process shift dramatically at the end of 2011.
Before 2011, the North American climate had slipped into an intense La Niña period. La Niñas occur when cool waters spread across the Pacific Ocean, changing the way weather systems travel across the American continent. During normal years and El Niño years, cold air bulges out of Canada, causing winter storms to swoop south and gather up humid air from the Gulf of Mexico. Then the storms careen up the East Coast, glance off Cape Hatteras and slam into Cape Cod as raging Northeasters, which hang around through several erosion-causing cycles of high tides.