As the seas rise, a slow-motion disaster gnaws

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As the seas rise, a slow-motion disaster gnaws

Part 1: A Reuters analysis finds that flooding is increasing along much of the nation’s coastline, forcing many communities into costly, controversial struggles with a relentless foe.

WALLOPS ISLAND, Virginia – Missions flown from the NASA base here have documented some of the most dramatic evidence of a warming planet over the past 20 years: the melting of polar ice, a force contributing to a global rise in ocean levels.

The Wallops Flight Facility’s relationship with rising seas doesn’t end there. Its billion-dollar space launch complex occupies a barrier island that's drowning under the impact of worsening storms and flooding.

NASA's response? Rather than move out of harm’s way, officials have added more than $100 million in new structures over the past five years and spent $43 million more to fortify the shoreline with sand. Nearly a third of that new sand has since been washed away.

Across a narrow inlet to the north sits the island town of Chincoteague, gateway to a national wildlife refuge blessed with a stunning mile-long recreational beach – a major tourist draw and source of big business for the community. But the sea is robbing the townspeople of their main asset.

The beach has been disappearing at an average rate of 10 to 22 feet (3 to 7 meters) a year. The access road and a 1,000-car parking lot have been rebuilt five times in the past decade because of coastal flooding, at a total cost of $3 million.

Officials of the wildlife refuge say they face a losing battle against rising seas. In 2010, they proposed to close the beach and shuttle tourists by bus to a safer stretch of sandy shoreline.

The town revolted. Like many local residents, Wanda Thornton, the town’s representative on the Accomack County board of supervisors, accepts that the sea is rising, but is skeptical that climate change and its effects have anything to do with the erosion of the beach. As a result, “I’m just not convinced that it requires the drastic change that some people think it does,” she said.

Four years on, after a series of angry public meetings, the sea keeps eating the shore, and the government keeps spending to fix the damage.

Wallops officials and the people of Chincoteague are united at the water’s edge in a battle against rising seas.

Exclusive: Coastal flooding has surged in U.S., Reuters finds

All along the ragged shore of Chesapeake Bay and the Atlantic coast of the Delmarva Peninsula, north into New England and south into Florida, along the Gulf Coast and parts of the West Coast, people, businesses and governments are confronting rising seas not as a future possibility. For them, the ocean’s rise is a troubling everyday reality.

This is the first in a series of articles examining the phenomenon of rising seas, its effects on the United States, and the country’s response to an increasingly watery world. Other stories will show how other nations are coping.

In cities like Norfolk, Virginia, and Annapolis, Maryland, coastal flooding has become more frequent. Beyond the cities, seawater and tidal marsh have consumed farmland and several once-inhabited islands. Here in Accomack County alone, encroaching seawater is converting an estimated 50 acres (20 hectares) of farmland into wetlands each year, according to a 2009 Environmental Protection Agency study.

“It breaks my heart to think about it,” said Grayson Chesser, a decoy carver whose ancestors arrived in the Chesapeake Bay area four centuries ago. He lives outside Saxis, a town that’s losing ground to the water. Some nearby villages have disappeared altogether. “You’ve got to deal with the fact that it’s happening – and what are you going to do with those of us on the edge?”

It’s a question the U.S. government is dodging. More than 300 counties claim a piece of more than 86,000 miles (138,000 km) of tidal coastline in the United States, yet no clear national policy determines which locations receive help to protect their shorelines. That has left communities fighting for attention and resources, lest they be abandoned to the sea, as is playing out in Chincoteague.

“If we can’t make a decision about rising sea level in a parking lot, we’re in trouble as a nation,” said Louis Hinds, former manager of Chincoteague National Wildlife Refuge.

Tidal waters worldwide have climbed an average of 8 inches (20 cm) over the past century, according to the 2014 National Climate Assessment. The two main causes are the volume of water added to oceans from glacial melt and the expansion of that water from rising sea temperatures.

In many places, including much of the U.S. Eastern Seaboard, an additional factor makes the problem worse: The land is sinking. This process, known as subsidence, is due in part to inexorable geological shifts. But another major cause is the extraction of water from underground reservoirs for industrial and public water supplies. As aquifers are drained, the land above them drops, a process that can be slowed by reducing withdrawals.

“You’ve got to deal with the fact that it’s happening – and what are you going to do with those of us on the edge?”

Grayson Chesser, lifelong resident, Accomack County, Virginia

For this article, Reuters analyzed millions of data entries and spent months reporting from affected communities to show that, while government at all levels remains largely unable or unwilling to address the issue, coastal flooding on much of the densely populated Eastern Seaboard has surged in recent years as sea levels have risen.

These findings, first reported July 10, aren’t derived from computer simulations like those used to model future climate patterns, which have been attacked as unreliable by skeptics of climate change research. The analysis is built on a time-tested measuring technology – tide gauges – that has been used for more than a century to help guide seafarers into port.

Reuters gathered more than 25 million hourly readings from National Oceanic and Atmospheric Administration tide gauges at nearly 70 sites on the Atlantic, Gulf and Pacific coasts and compared them to flood thresholds documented by the National Weather Service.

The analysis was then narrowed to include only the 25 gauges with data spanning at least five decades. It showed that during that period, the average number of days a year that tidal waters reached or exceeded flood thresholds increased at all but two sites and tripled at more than half of the locations.

ABOUT THE ANALYSIS

When Reuters set out to measure the frequency of flooding along the U.S. coastline, it turned to one of the nation’s longest-running sentinels of the changing oceans: tide gauges.

These devices, originally deployed to assist navigation by mariners, are critical to understanding the interaction between land and sea. The gauges measure the level of the surface of the sea, relative to a fixed point on land.

Some gauges have been in operation for a century or more, providing a long-term view of sea levels unavailable from satellites. A gauge in San Francisco, installed in 1854, provides the Western Hemisphere’s longest-running continuous record of sea levels.

The National Oceanic and Atmospheric Administration operates more than 200 tide gauges on the U.S. coast and the shores of the Great Lakes. Most of the data is online and available to the public through multiple portals operated by NOAA. The gauges “give a very unbiased view of what’s going on along the coast,” said William Sweet, a NOAA oceanographer.

At nearly 70 of those gauges, National Weather Service forecasters have published thresholds for when flooding can begin. Reuters downloaded more than 25 million hourly readings from those gauges and compared them to the flood thresholds.

Reuters then determined how many days in each meteorological year had at least one hour when the sea level equaled or exceeded the flood threshold. A meteorological year, from May 1 through April 30, is used so the winter season is not split.

If a gauge did not have data from at least 292 days in a year, or 80 percent of the days in a typical year, the results were ignored.

For the purposes of measuring changes over multiple decades, the analysis then focused on the 25 gauges with data spanning five decades. The average annual flood-level days were then calculated for two periods: pre-1971 and 2001-present. Gauges had to have at least five years of results in a time period to be included.

The methodology was adapted from those used by researchers at NOAA and Old Dominion University in Norfolk, Virginia. Reporters sought their input on how to analyze the data and how to present the findings.

Since 2001, water has reached flood levels an average of 20 days or more a year in Annapolis, Maryland; Wilmington, North Carolina; Washington, D.C.; Atlantic City, New Jersey; Sandy Hook, New Jersey; and Charleston, South Carolina. Before 1971, none of these locations averaged more than five days a year. Annapolis had the highest average number of days a year above flood threshold since 2001, at 34. On the Delmarva Peninsula, the annual average tripled to 18 days at the Lewes, Delaware, tide gauge.

The flood threshold does not measure actual flooding. It indicates the level at which the first signs of flooding are likely to appear – ponding on pavements and such. The higher the reading, the higher the probability of closed roads, damaged property and overwhelmed drainage systems. Scientists consider the readings to be a reliable indicator of actual flooding.

The Reuters analysis shows that the “impacts of climate change-related sea level rise are increasing frequencies of minor coastal flooding,” said William Sweet, an oceanographer for NOAA who led a team of scientists that released similar findings in late July. The NOAA study examined 45 gauges and found that flooding is increasing in frequency along much of the U.S. coastline and that the rate of increase is accelerating at sites along the Gulf and Atlantic coasts.

The coastal flooding is often minor. Its cumulative consequences are not. As flooding increases in both height and frequency, it exacts a toll in closed businesses, repeated repairs, and investment in protection. In effect, higher seas make the same level of storm and even the same high tides more damaging than they used to be.

In Charleston, a six-lane highway floods when high tides prevent storm water from draining into the Atlantic, making it difficult for half the town’s 120,000 residents to get to three hospitals and police headquarters. The city has more than $200 million in flood-control projects under way.

In Annapolis, home to the U.S. Naval Academy, half a foot of water flooded the colonial district, a National Historic Landmark, at high tide on Chesapeake Bay during rainstorms on April 30, May 1, May 16 and Aug. 12. Shopkeepers blocked doorways with wood boards and trash cans; people slipped off shoes to wade to work in bare feet.

Tropical storm flooding has worsened, too, because the water starts rising from a higher platform, a recent study found.

When Tropical Storm Nicole struck Maryland in 2010, it was no stronger than storms in 1928 and 1951 that were “non-events,” said the study’s author, David Kriebel, a Naval Academy ocean and coastal engineer. Nicole, by contrast, swamped downtown Annapolis and the Naval Academy. “It’s partly due to ground subsidence,” Kriebel said. “Meanwhile, there’s been a worldwide rise in sea level over that period.”

In tidal Virginia, where the tide gauge with the fastest rate of sea level rise on the Atlantic Coast is located, a heavy rainfall at high tide increasingly floods roads and strands drivers in Norfolk, Portsmouth and Virginia Beach.

Coastal flooding already has shut down Norfolk’s $318 million light rail system several times since it opened in 2011. Mayor Paul Fraim said he needs $1 billion for flood gates, higher roads and better drains to protect the city’s heavily developed shoreline.

LEGACY OF INACTION

The nation’s capital isn’t immune. The Potomac River turns into a tidal estuary

READ MORE...

http://www.reuters.com/investigates/special-report/waters-edge-the-crisis-of-rising-sea-levels/