Flooding hot spots: Why seas are rising faster on the U.S. East Coast – “These coastal areas are more vulnerable than they realize to short-term rapid acceleration of sea level rise”

Desdemona Despair

By Jim Morrison
24 April 2018

(Yale E360) – Seen from a pedestrian footbridge overlooking Myrtle Park — a sliver of land that Norfolk, Virginia is allowing to revert to wetlands — the panorama of surrounding homes illustrates the accelerating sea level rise that has beleaguered this neighborhood along the Lafayette River.

A grey house, among the first raised in the area, is slightly elevated on cinderblocks, standing 2 feet off the ground. Nearby, owners of a white-sided house with black shutters have lifted their dwelling about 4 feet above ground level. And on the right, a brick house resting on cinderblocks rises incongruously 11 feet above the street.

The roads circling Myrtle Park are cracked and disintegrating due to frequent flooding. Tidal grasses like Spartina are springing up. The boulevard a block away, which leads to the world’s largest naval base, floods several times a year and the frequency is increasing.

“Things are getting worse,” says William “Skip” Stiles, executive director of Wetlands Watch, a local advocacy group. “We’re now requiring you to go even higher in Norfolk because we get it.”

What Norfolk gets is that while sea level is rising globally at about a tenth of an inch per year, cities along the Eastern Seaboard of the United States — including Norfolk; Baltimore; Charleston, South Carolina; and Miami, among others — have suffered “sunny day” flooding from seas rising far faster than the global average. One study published last year shows that from 2011 to 2015, sea level rose up to 5 inches — an inch per year — in some locales from North Carolina to Florida. Given growing concerns over the flooding, scientists are now working to unravel the mystery of why some parts of the globe are experiencing so-called “sunny day” flooding that had not been expected for decades under conventional sea level rise projections.

Along the southeastern coast of the U.S., researchers have zeroed in on three factors that have made this shoreline a regional hot spot of sea level rise. They include a slowing Gulf Stream, shifts in a major North Atlantic weather pattern, and the effects of El Niño climate cycles.

“These coastal areas are more vulnerable than they realize to short-term rapid acceleration of sea level rise,” says Andrea Dutton, a University of Florida geologist who studies the history of sea level fluctuations. “If they’re hanging their hat on sea level rise projections looking at the potential over decades, they need to refocus and think about the potential for short-term variability in that rate.” [more]

Flooding Hot Spots: Why Seas Are Rising Faster on the U.S. East Coast

ABSTRACT: Observational evidence points to a warming global climate accompanied by rising sea levels which impose significant impacts on island and coastal communities. Studies suggest that internal climate processes can modulate projected future sea level rise (SLR) regionally. It is not clear whether this modulation depends on the future climate pathways. Here, by analyzing two sets of ensemble simulations from a climate model, we investigate the potential reduction of SLR, as a result of steric and dynamic oceanographic affects alone, achieved by following a lower emission scenario instead of business-as-usual one over the twenty-first century and how it may be modulated regionally by internal climate variability. Results show almost no statistically significant difference in steric and dynamic SLR on both global and regional scales in the near-term between the two scenarios, but statistically significant SLR reduction for the global mean and many regions later in the century (2061–2080). However, there are regions where the reduction is insignificant, such as the Philippines and west of Australia, that are associated with ocean dynamics and intensified internal variability due to external forcing.

Internal climate variability and projected future regional steric and dynamic sea level rise