• A chart from the NOAA report shows four possible sea level rise scenarios. The report makes no explicit predictions, instead advocating that policymakers consider all the possibilities in making plans.

    Credit: NOAA

    A chart from the NOAA report shows four possible sea level rise scenarios. The report makes no explicit predictions, instead advocating that policymakers consider all the possibilities in making plans.
  • Surge waters wash over a Lewes, Del., shore road as Hurricane Sandy moves past the state on the way to landfall in New Jersey in a time-lapse video posted by the Delaware Sea Grant.
    Surge waters wash over a Lewes, Del., shore road as Hurricane Sandy moves past the state on the way to landfall in New Jersey in a time-lapse video posted by the Delaware Sea Grant.

The National Oceanographic and Atmospheric Administration (NOAA) released a report this month examining the risks to U.S. coastal areas of rising sea levels expected in the coming century. Titled “Global Sea Level Rise Scenarios for the National Climate Assessment,” the report considers a wide range of possibilities reflected in the scientific literature — from a mere six-inch rise over 100 years (which would just repeat the last 100 years’ change) to a six-foot increase in global sea levels, which could happen if melting of Antarctic and Greenland ice sheets happens at the fastest pace scientists have conjectured may occur.

The upper-bound six-foot increase is unlikely to happen, the report says. But on the other hand, the rosy scenario — just six inches of rising sea — is just as unlikely. Somewhere in the middle is the safer bet. But even in the mid-range guess, the report describes two possibilities — an “intermediate-high” scenario in which seas would rise by 3.9 feet, and an “intermediate-low” scenario in which they would rise by 1.6 feet.

Neither of these possibilities would be trouble-free. And that has policymakers worried. But the possible reaction of policymakers has a variety of stakeholders worried, including property owners and builders who fear that government reaction to the perceived risk might harm their interests.

Low-lying Delaware is one of the Atlantic Coast states with a major exposure to ocean flooding, and sea level rise could damage the state badly, reports the Wilmington, Del., News Journal (“Report displays future concerns on sea-level rise,” by Jeff Montgomery and Molly Murray). “Attention to NOAA’s finding was almost immediate in Delaware, sharpening debate over a statewide plan for adapting to rising seas – or retreating from coastal flooding,” the paper reports.

Delaware’s Department of Natural Resources and Environmental Control has a Sea Level Rise Advisory Committee tasked with developing an adaptation plan for the state which would theoretically guide a comprehensive response to rising seas.

Following release of the NOAA paper, some citizen groups urged the committee to recommend more drastic measures. But business-sector members of the committee pushed back, the News Journal reports: “One business group member of the Sea Level Rise Advisory Committee, however, dismissed the NOAA report as ‘opinion.’ Another warned that ‘there will be war’ if DNREC presses ahead with a proposal to make future sea-level rise a factor in land-use planning and on decisions governing wells and wastewater systems.”

The NOAA report, in fact, doesn’t take a position on which of the possible sea level rise projections policymakers or citizens should believe. Instead, it says that good planning should take all the possibilities into account, and leave flexibility for responding to any of the likely outcomes. “Scenarios do not predict future changes, but describe future potential conditions in a manner that supports decision-making under conditions of uncertainty,” says the report. “Scenarios are used to develop and test decisions under a range of plausible futures. This approach strengthens an organization’s ability to recognize, adapt to, and take advantage of changes over time.”

During Hurricane Sandy, a wastewater treatment plant at Lewes, Del., flooded and trapped workers at the plant. Workers were rescued by a Humvee, but the plant had to spill two million gallons of sewage. But if sea level rise approaches the upper bounds in the NOAA report, the News Journal points out, “average sea level at Lewes would be six inches higher by 2100 than the level recorded during Superstorm Sandy’s peak in late October – every single day.”

But business interests resist the idea of incorporating projected sea level rise into today’s regulations. Homebuilder Kevin Whittaker commented: “It’s one thing to say that I’m in a flood plain. It’s another to say that sea level is going to rise a meter and a half around the property. That’s not science. That’s not a factual thing. It’s based on what you think sea-level rise will do, and it impacts a person’s private property rights.”