A new report from the Virginia Institute of Marine Science shows a steady rise in relative sea level along Galveston Island with sea level rising presently at the highest rate of 32 monitored locations around the country.
“The sea level rise rate in Galveston is accelerating and has been over the past couple of years, increasing slightly faster than in the previous 10-year period,” Molly Mitchell, a researcher on the project, said.
The report comprises interactive web-based charts projecting sea level out to the year 2050 based on analysis of tide-gauge records for 32 stations along the U.S. coastline, including the Galveston Pier 21 station operated by the National Oceanic and Atmospheric Administration.
The report measures relative sea level rise, taking into account both rising waters and subsidence or sinking of the land.
Rockport, to the south, showed a fast rise rate of 6.72 millimeters per year compared with Galveston’s rate of 6.19, and the highest rate of acceleration through 2018, making its year 2050 projection 2.6 feet above 1992 levels.
Sea level at Galveston will rise to about 1.6 feet above 1992 levels by 2050 if current conditions continue, according to the report.
Sea level in coastal waters around Galveston rose a little more than 2 feet in the 107 years from 1908 to 2015, according to data collected by NOAA at the Pier 21 station.
The Virginia Institute report is designed to localize sea level rise rates and to make them more timely than global sea level projections that are more often in front of the public, David Malmquist, a spokesperson for the Virginia team, said.
The idea behind the report is to give communities tools to look into the future with sea level in mind, researchers said.
“Really, our goal with this kind of work, making these projections, is to give people good information they can use for future planning,” Mitchell said.
“It’s about how we learn to organize our landscape, answering questions like where do we want to put new developments and major roadways.”
The report shows several measures, including monthly mean sea level, a figure obtained through tidal measurements at the Pier 21 station, absent predictable tidal variations. Monthly mean sea level is the measure most concerned with the rate of sea-level change relative to piers, buildings, homes and streets.
The Galveston report shows a linear rise in sea level due to steric processes or changes in density and volume of seawater relative to temperature or salinity. Warming and freshening of seawater reduces density of the water, thus increasing volume and contributing to sea level rise, according to the report.
Galveston waters are also affected, though at a rate of medium acceleration, by global rise associated with ice melts in Greenland and Antarctica, and by subsidence of the land although the rate of subsidence appears to have leveled off in recent years.
These reports, in addition to informing planning for development of housing and roads, also predict the need for open land or buffers between shoreline and uplands where coastal marsh wetlands can retreat or migrate as sea level rises over time, Mitchell said.
“We have been talking with decision makers in Maryland and Virginia, in the Chesapeake Bay area, about this,” Mitchell said.
“I think it’s early yet, but the message is starting to get through that we have to make a decision about whether we want wetlands to persist and how we are going to use the land immediately behind the wetlands.”
To see the full Galveston report, visit www.vims.edu/research/products/slrc/localities/gatx/index.php.