Jeff Montgomery, and Molly Murray

The News Journal

Global warming is likely to shatter Delaware's coastal flooding records within two decades and "near certain" to spawn vastly destructive inundations in some locations before the end of the century, a national environmental group reported Tuesday.

Current worst-case flooding scenarios – like rising waters from Superstorm Sandy, Hurricanes Irene and Isabel and the Mother's Day Nor'easter of 2008 – will become more frequent and worse both in the short term and long term throughout Delaware and all of the Delmarva Peninsula, according to Climate Central.

At risk are hundreds of thousands of people, billions of dollars in property and roads, schools and power plants. The Delmarva portion of the Sea Level Rise initiative completes flood and climate change vulnerability for all Atlantic Coastal States except Pennsylvania, Strauss said. The next phase of the project are the Gulf Coast, Alaska and Hawaii, he said.

The new report includes an interactive, online mapping tool that allows home and business owners and state and local planners to assess the localized impacts of climate change, find the most vulnerable citizens and plan for the future, said Ben Strauss, chief operating officer for Climate Central and director of the Program on Sea Level Rise.

Strauss said that on Delmarva, residents face not only rising seas from climate change but also an added bump in sea level as the land settles.

"People will see properties go from rarely flooded to flooded every few years," he said.

Supporting the forecasts are National Oceanic and Atmospheric Administration scenarios issued in late 2012 anticipating a 1.5 to 6.6 foot rise in sea levels along the Mid-Atlantic. Levels will rise, scientists projected, because of global warming – largely triggered by human emissions of heat trapping gases – and coastal sinking.

Increasingly, projections are leaning toward the high side, increases that would add to already serious tidal flooding vulnerabilities.

In Lewes, for instance, residents may see a major flooding event every 12 years by 2020 because of higher water, and every three years by the end of a new 30-year mortgage taken out today. By 2060, Strauss said, Lewes will see flooding worse than the 1962 storm of record once a year.

At Reedy Point along the Delaware River at the Chesapeake & Delaware Canal, "floods exceeding today's record become every year events, or more-frequent, by mid-century," according to the report.

And on Delmarva and even Delaware, the risk goes beyond the obvious of the ocean coast.

"Say Sea Level Rise and the first thing people see in their mind's eye is the beach. I think the biggest threat is bay flooding," he said. But "they have this dramatic image of a home being smashed by waves."

Bay shores and inland waterways are typically flat so there is a much bigger flooding risk, he said.

Susan Love, a Coastal Programs planner with the Department of Natural Resources and Environmental Control, said that Delaware already has worked for years to prepare. Efforts so far include development of statewide vulnerability assessments similar to the wider-scale ones released by Climate Central, and recommendations for state agency policies to prevent or reduce losses.

"This is a national tool, and I think it's very important for people to be able to see that sea level rise is an issue in Delaware, New Jersey, Maine, Florida and California," Love said. "It's really important that we do see this as a national issue."

Delaware City Manager Richard Cathcart said that his community needs no convincing about risks and costs of coastal flooding. The community already keeps mobile pumps on standby when storms threaten. State lawmakers set aside $500,000 to help the community with flooding, with officials waiting for final word on an even larger federal grant to better manage surges from the Delaware River.

"Up to now we've been pumping water coming in from the river out of our stormwater drains back into the river – recirculating it, just to keep ahead of the surge, so the streets don't flood," Cathcart said.

Even last week, when there was no extreme rainfall or storms, coastal areas along the Delaware River and Bay saw high water and flooding thanks to the influence of the full moon.

Pennsylvania State University researcher Michael Mann, whose groundbreaking work helped focus global attention on rising global temperatures, said in an email Tuesday that efforts like the Climate Central projections are important.

"The first rule in risk mitigation is that you make contingency plans for worst-case scenarios – after all, this is why we purchase fire insurance for our homes," Mann said.

The United Nations Intergovernmental Panel on Climate Change noted in its most recent report that Antarctic ice melt is occurring "well ahead" of earlier estimates," Mann said, adding to concerns that worst-case increases along the mid-Atlantic will exceed 6 feet.

The report comes with plenty of lead time so property owners, planners and state officials have time to react, adjust and make plans for the future.

At the University of Delaware Sea Grant College Program, Wendy Carey is already working with coastal officials to develop hazard mitigation plans to help cope with the impacts from climate change, including sea level rise. Both Lewes and Delaware City have plans in place.

And she is working on a new tool that home and business owners can use to provide online and interactive community flood inundation maps. They will help coastal residents look at flood insurance needs.

Another University of Delaware team that includes State Climatologist Dan Leathers has developed interactive flood risk maps for the Delaware River. The Delaware project may be expanded to include all of Delmarva.

Carey said that even with these tools, planning for the future needs to start now because "a significant amount of time is required" to change public attitudes, build consensus, develop a plan and reach long-term goals.

"Being proactive now simply makes sense," she said.

Individual property owners, for instance, can build to a higher standard by incorporating a foot or more above what is required by Federal Flood Insurance regulations.

In the meantime, those property owners get the added benefit of resilience from coastal storms.

"It's a win-win, no-regrets strategy that prepares communities for future risk," she said. "There's no benefit on waiting to see" what happens in the future.

Strauss said it his his hope that people will use the mapping tool to see their risk and plan for the future. The information is not real-time storm surge or flood risk monitoring, he cautioned. Instead, it shows people "how deep the water could be ... I hope this is a part of making it real for people."

All over Delmarva, there are reminders of past flood levels. In Wachapreague, Virginia, for instance, there is a sign on the corner of the Wachapreague Inn that shows the high water mark from Hurricane Isabel. Along Savannah Road in Lewes, there is a similar sign that shows the storm tides for several weather events including the bench mark March Storm of 1962.

"Our product is a way for people to get some sense" of how high the water can be, Strauss said.

To find out why tides are higher during full moons and get answers to your other science questions every Tuesday, friend MollyMurraytnj on Facebook.

Contact Jeff Montgomery at (302) 463-3344 or jmontgomery@delawareonline.com.

Molly Murray at (302) 463-3334 or mmurray@delawareonline.com.

What's at Risk in Delaware

In next 20 years extreme flood events will likely be at 5-feet and higher above the current high tide line

62,000 acres of land

$1.1 billion in property -- about half of it in five zipcodes: Wilmington ( 19801) New Castle ( 19720) Dover ( 19901) Rehoboth Beach ( 19971) Bethany Beach ( 19930)

20,000 homes

19,000 year-round residents

428 miles of road

9 churches

2 power plants

87 EPA-listed sites including a range from waste water treatment plants to hazardous waste sites.

By the Turn of the Century, when extreme flood events will be 9-feet and higher above the current high tide line.

104,000 Acres of land

$2 billion in property

40,000 homes

41,000 year-round residents

782 miles of roads

36 Churches

4 Power Plants

135 EPA- listed sites

What's at Risk in Maryland

In next 20 years extreme flood events will likely be at 5-feet and higher above the current high tide line

265,000 Acres of land

$19.6 billion in property ( 40-percent of it in Worcester County and 1/3 in Ocean City)

41,000 homes

55,000 year-round residents

1,488 miles of roads

6 museums

98 churches

3 power plants

154 EPA-listed sites

Highest exposure: Worcester and Somerset counties with threats to land, property and other assets.

By the Turn of the Century, when extreme flood events will be 9-feet and higher above the current high tide line

440,000 Acres of land

$42.3 billion in property

94,000 homes

132,000 year-round residents

3,009 miles of roads

18 museums

188 churches

7 power plants

335 EPA-listed sites

What's at Risk in Virginia

In next 20 years extreme flood events will likely be at 5-feet and higher above the current high tide line

250,000 acres of land

$17.4 billion in property

54,000 houses

107.000 people

1,469 miles of roads

7 schools

67 churches

1 power plant

148 EPA-listed sites

By the Turn of the Century, when extreme flood events will be 9-feet and higher above the current high tide line

490,000 acres of land

$54.8 billion in property

200,000 homes

466,000 residents

4,500 miles of roads

77 schools

325 churchs

5 power plants

535 EPA-listed sites

Top Five storm tides for selected Delmarva locations

All are measured in feet at MHHW, which Climate Central describes at thehighest high tide line

Lewes

3/6/1962 (nor'easter) -- 4.57

1/4/1992 (nor'easter) -- 4.09

10/29/2012 ( Superstorm Sandy) -- 4.04

1/28/1998 (nor'easter) -- 3.97

2/5/1998 (nor'easter) -- 3.84

Cambridge, MD

9/19/2003 ( Hurricane Isabel) -- 4.4

9/6/1996 (Tropical Storm Fran) -- 2.81

4/17/2011 (nor'easter) -- 2.67

12/21/2012 ( nor'easter) -- 2.61

10/29/2012 ( Superstorm Sandy) -- 2.50

Kiptopeke, VA

3/7/1962 ( nor'easter) -- 4.13

11/13/2009 (Nor'Ida) -- 3.98

10/29/2012 ( Superstorm Sandy) -- 3.85

9/18/2003 (Hurricane Isabel) -- 3.58

8/28/2011 (Hurricane Irene) -- 3.54

Delaware City, DE

10/30/2012 (Superstorm Sandy) -- 3.73

12/21/2012 (No-name storm) -- 3.47

4/17/2011(nor'easter) -- 3.38

8/5/2012 (storm) -- 3.13

8/28/2911 (Hurricane Irene) -- 2.83

Reedy Point

4/17/2011 (nor'easter) -- 3.4

12/21/2012 (No-name storm) -- 3.34

10/30/2012 (Superstorm Sandy) -- 3.26

10/25/1980 (storm) -- 3.04

9/19/2003 (Hurricane Isabel) -- 2.82