For Virginia, adapting to sea level rise starts with choosing a curve

By: - June 15, 2021 12:03 am

The Hampton Roads Bridge Tunnel. (Ned Oliver/ Virginia Mercury)

In a warming world of rapidly rising waters, there are at least nine possibilities for what tomorrow will look like at Sewells Point in Norfolk. 

All agree that by 2050 the sea will have overtaken more of the land than today. But by how much — half a foot, more than three feet or somewhere in between? 

When it comes to projections, “you’ve got this Tower of Babel,” said Skip Stiles, executive director of Norfolk-based nonprofit Wetlands Watch. 

“Curve of Babel” might be more appropriate. Over the past decade, state and federal scientists have been devising curves that show the trajectory sea level rise could take through the end of the century. The Army Corps has issued three, the National Oceanic and Atmospheric Administration five, and the Virginia Institute of Marine Science, which acts as the commonwealth’s advisor on coastal management and change, one. 

No one knows which, if any, will prove correct. Nevertheless, Gov. Ralph Northam in 2019 quietly threw his weight behind the NOAA “intermediate-high” curve, tucking a provision into an executive order declaring Virginia would use that projection as “the state standard for predicting sea level rise.” 

The decision largely flew below the radar. “Is the average homeowner or property owner aware of it? Probably not,” said Ann Phillips, a retired U.S. Navy rear admiral and Virginia’s special assistant to the governor for coastal adaptation and protection, a position created in 2018 specifically to deal with the effects of sea level rise. 

But while the selection of a state standard may have attracted little public notice, its effects will quite literally shape Virginia’s future landscape. Sea level rise adaptation will require an almost unparalleled bureaucratic response as state, local and federal planners are forced to revise building, bridge, road, dam, land use and other infrastructure standards to accommodate not only the encroachment of waters but also increased precipitation.

Building codes have traditionally been “historical looking,” said Carol Considine, an engineering professor at Old Dominion University and director of applied projects for the Commonwealth Center for Recurrent Flooding Resiliency. “They look backwards to what was climate before, and they don’t look forward to what climate is going to be. Having a forward-looking code is going to be important as climate changes.”

A range of projections exists for what sea level rise will look like at Sewells Point in Norfolk through 2050 and then the end of the century. (AdaptVa,

What the new state codes and standards will look forward to is the vision of the future sketched by NOAA’s intermediate-high scenario: 2.2 feet of sea level rise at Sewells Point by 2050. 

The projection is a little more conservative than the trajectory currently revealed by VIMS tide-gauge data: NOAA’s “intermediate curve is the one most similar to the historic record,” wrote VIMS scientist Molly Mitchell in an email. “Whether or not it is the most likely curve depends on future conditions (particularly rates of atmospheric warming), which at this point is unknown. The further out into the future we are looking, the more likely that things could vary from the historic trend (but how much is hard to say).” 

By going a little higher than the projection based on historical tide-gauge data, Virginia sought to chart a course that was “risk averse but not ridiculous,” said Phillips — “something that’s a little higher, that would force us to consider a future that might require a little more consideration for sea level rise than we’re currently seeing.” 

“We know that we may need to change the curve in the future. We said that in (the) executive order,” she said. But, she added, “you’ve got to start somewhere.” 

It was a sentiment shared by many other state and local policymakers. “For planning purposes, yes, you kind of have to pick a point and move from there,” said Virginia Beach stormwater engineer Toni Utterback. “The important thing to note for localities and the state is the science will change and the data will get better and we need to make adjustments accordingly.” Ben McFarlane, a senior regional planner with the Hampton Roads Planning District Commission, said that “while the one curve may not be the right curve — I don’t think there is one right curve — it’s a useful curve.” Stiles described the choice as a way of Virginia getting “everybody moving pretty much in the same direction.” 

“We could sit here and argue over which curve is right,” he said. “And the next thing you know, it’s 2040 and you’ve got a foot of water on the road.” 

How sea level rise curves are created

Sea level rise curves are the product of a host of information, from local changes in land levels and tide-gauge readings to global sea level data, predictions of future greenhouse gas emissions scenarios and knowledge about ice sheet dynamics. All show a consistent trend: Sea level rise is accelerating. 

The idea of releasing official curves that could be used broadly is a recent phenomenon. NOAA came out with its first set in 2012, and updated its projections in 2017. The U.S. Army Corps of Engineers released its own curves in 2013. Other, less popular curves have also been devised, including by the U.S. Department of Defense. 

The intent was to provide “a plausible range of futures,” said William Sweet, an oceanographer with NOAA’s National Ocean Service. “Let’s bound the plausible space for a global scenario. Let’s bring that down locally, because decisions are made locally. … And then let’s try to get some bounding of what’s more likely over the next several decades or not.”


Virginia’s choice of a sea level rise standard wasn’t unprecedented. When Northam signed a November 2018 executive order declaring Virginia “must have a standard approach for predicting sea level rise when scoping, designing, siting and constructing state-owned buildings,” Hampton Roads had already been grappling with the question of a standard for several years. 

Just a month prior, the region’s planning district commission — representing 17 cities and counties in Virginia’s southeastern corner — had adopted a resolution recommending local governments assume 1.5 feet of sea level rise in planning projects over the 2018-2050 span, three feet for the 2050-2080 horizon and 4.5 feet for even longer-term decisions. Virginia Beach and the Port of Virginia would later adopt closely comparable projections.

It was not surprising that Hampton Roads was ahead of the curve. There, rising seas and land subsidence have combined to give the region the fastest rate of sea level rise on the East Coast. Sewells Point has seen sea level rise more than 18 inches over the past century, according to tide-gauge data. Phillips testified to U.S. House members in November 2019 that state officials “expect an additional 18 inches of relative sea level rise by mid-century.” 

Retreat is largely not on the planning table: Only recently did Gov. Ralph Northam’s administration acknowledge that “protecting every component of the built environment exactly where it stands today is not realistic.” 

What that leaves is adaptation.

“We want Virginia Beach to remain a viable coastal destination for people to come to,” said city stormwater engineer C. J. Bodnar. Utterback said “the discussion in Virginia Beach is learning to live with water.” 

The Virginia Institute of Marine Science, in recommending projections for the state, took a similar tack: “Selecting an appropriate sea level projection for planning purposes is a critical step towards promoting resilience,” the institute wrote in February 2019. 

A statue of Neptune on Virginia Beach’s oceanfront. (Ned Oliver/Virginia Mercury)

Different standards for different needs

While Hampton Roads has embraced a 1.5 feet by 2050 standard and the state the 2.2 feet projected by the NOAA intermediate-high curve, the two aren’t as incompatible as they might appear, said state and local officials. 

McFarlane described the new state standard as “pretty consistent with what we’re doing” in the region. And Virginia’s Coastal Resilience Master Planning Framework, a precursor to a state master plan the Northam administration is hurrying to release before a new governor takes office in January, said the Hampton Roads projections “closely align with the NOAA Intermediate-High curve.”

Why the two standards differ at all comes down to two things: evolving understanding of how sea level rise is occurring and the kind of infrastructure state and local governments are trying to build. 

Hampton Roads was the first region in Virginia to set a sea level rise standard, at a time when “there really wasn’t anything coming out from the state,” according to McFarlane. 

“We started our study back in 2014. We used the most relevant information at the time to move forward. Now the state is just beginning theirs, and rightfully so they’re going to use the best information” now available, said Utterback. “We know the science is going to change. We know there’s an acceleration occurring.” 

Perhaps more consequentially, the variation reflects the degree to which buildings and roads, dams and drainage systems are built with a lifespan. Few projects are intended to last for centuries. Some, like telecommunications facilities or stormwater systems, tend to be replaced every 20 to 30 years due to technology changing or wearing out. Others, like many bridges and other major state-owned infrastructure, are built to last much longer. 

“When we look at buildings, we want to project what is the anticipated life of the structure,” said Considine. 

Both Old Dominion University and VIMS have highlighted the link between project lifespan and official standards in recommendations on sea level rise projections and standards. 

“Considering that new construction building life would extend beyond” the projection put forward by VIMS for sea level rise through 2050, “it is necessary to consider NOAA climate scenarios,” Old Dominion University researchers wrote. VIMS concluded that “the Intermediate curve is (a) potential target for infrastructure that can tolerate moderate flooding,” but “flood intolerant infrastructure should incorporate higher curves.”

Without unlimited public funds, much of sea level rise planning comes down to a question of how much risk people are willing to swallow — and, in a nation where large swathes of the electorate still do not accept climate change is occurring, how much they will acknowledge.

NOAA’s “extreme” and “high” sea level scenarios, Bodnar pointed out, project between nine and 11 feet of sea level rise at Sewells Point by 2100, while Virginia Beach has an average elevation of about 10 feet. 

“How do you plan for something like that?” asked Utterback. “It’s hard enough to get buy-in from citizens to understand this is happening, let alone happening that much.” 

McFarlane said most planning comes down to “balancing costs and benefits.” 

“For some projects the benefits of being conservative will be bigger; for some the costs will be bigger,” he said. 

Reconciling local, state and federal standards

Already, Virginia’s choice to embrace NOAA’s intermediate-high curve has had ripple effects. 

On Valentine’s Day 2020, the Virginia Department of Transportation began using the intermediate-high curve as part of its bridge design standards for replacing coastal or near coastal bridges. A study conducted with VIMS to identify “projected impacts from sea level rise, subsidence and recurrent flooding on existing and planned road infrastructure” will base its analyses on the state curve, wrote VDOT spokesperson Marshall Herman in an email. 

New regulations from the Department of Environmental Quality that attempt to incorporate sea level rise into land use decisions in the Chesapeake Bay watershed also rely on the intermediate-high curve, as does new guidance for living shorelines. And state floodplain managers are mapping “sea level rise inundation areas” based on the chosen NOAA curve. 

What we’re trying to do in the commonwealth is get ahead of (sea level rise) and start to deal with it now instead of getting caught,” said Phillips. 

Setting a state standard means that “now it’s real,” said Stiles of Wetlands Watch. “It’s not just, ‘Hey guys, you guys need to think about intermediate-high. These are actual design standards.” 

Flooded low-lying land near a park bench in Alexandria, Va., in December 2020. (Sarah Vogelsong/Virginia Mercury)

Still, Stiles cautioned that major gaps remain. State standards apply only to agency decisions and state-owned property, whereas in the absence of a county or city ordinance, local infrastructure like schools or fire stations aren’t required to be built according to any particular sea rise projection. 

“There’s no mandate that schools need to be built to this curve,” he said. “That’s not state infrastructure, so it’s not covered by the executive order. But it is critical public infrastructure.”

And even as Virginia has moved to standardize its projections, one outlier persists: the Army Corps of Engineers, whose 2013 curves — and particularly its default intermediate curve — chart a much more conservative path for sea level rise than any other projections. Corps work is designed based on these curves, and while local governments can negotiate for projects to be built to higher sea level rise standards, they must pay for the difference. 

It’s a situation Phillips has complained about on the federal level. 

Any Army Corps analysis is “underestimating the rate of change, depth and future impacts, which results in under engineered and underestimated solutions,” she told the U.S. House Subcommittee on Water Resources and the Environment in November 2019. “In essence, by using these very conservative sea level rise scenario-planning curves, and not considering local analysis and rates of change, (the Army Corps) is ‘shooting behind the duck’ — wasting federal dollars in a tail chase to address an ever-expanding problem and delivering underdesigned and underengineered outcomes.” 

McFarlane said the Hampton Roads Planning District Commission largely hadn’t factored the Army Corps projections into its regional policy.

“The corps’ ones are a little old now, so we don’t use them much anymore,” he said. “They’re based on some older science.” 

Army Corps of Engineers spokesperson Gene Pawlik said in an email that the corps plans to review its sea level rise scenarios ahead of NOAA’s next release of official mean sea levels in 2025 but the corps “feels its scenarios are still actionable for its purposes at this time.”

“Different federal agencies, state governments and other entities each have their own preferred sea level scenarios because they have their own purposes, preferences and risk tolerances,” he wrote. For the Army Corps, which focuses on engineering and construction, “these scenarios include sea levels that are considered plausible for project planning and design purposes, but not all sea levels that are theoretically or physically possible. Other scenarios might be more useful for other state, federal or other entities with different mandates.”

As climate change research continues to alter scientists’ understanding of how sea level rise will occur over the next decades, policies too will have to adapt to the changing circumstances, said state officials. 

“It’s a long road ahead,” said Phillips, “but we start with setting standards.” 

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Sarah Vogelsong
Sarah Vogelsong

Sarah is Editor-in-Chief of the Mercury and previously its environment and energy reporter. She has worked for multiple Virginia and regional publications, including Chesapeake Bay Journal, The Progress-Index and The Caroline Progress. Her reporting has won awards from groups such as the Society of Environmental Journalists and Virginia Press Association, and she is an alumna of the Columbia Energy Journalism Initiative and Metcalf Institute Science Immersion Workshop for Journalists.