A sea level rise study by researchers at Texas A&M University at Corpus Christi predict the Galveston Bay and the Gulf of Mexico could rise more than 4 feet in the next 100 years.
Almost 80 percent of Galveston County households could be displaced by 2109 if water levels in the Gulf of Mexico and Galveston Bay rise as quickly as they have during the past 100 years.
Gauges at the Port of Galveston’s Pier 21 show the water is 2.3 feet higher today than it was in 1909.
If that trend continues, the rising water would chase thousands of homeowners away from the coast and cause billions of dollars in damage to the area’s water, sewer and utility systems, according to a study of sea level rise released earlier this month by three researchers from the Harte Research Institute for Gulf of Mexico Studies at Texas A&M University at Corpus Christi.
But a well-known coastal geologist disagrees with the study’s findings, calling them extreme and alarmist. The world’s best scientists agree the sea level is rising at half that rate, he said.
Quickly Rising
As alarming as a repeat of the last 100 years of sea level rise would be, the A&M researchers predict it actually could be much worse.
Estimates that the rate of sea level rise will remain the same are overly conservative, David Yoskowitz, one of the study’s authors, said.
It is much more reasonable to expect the rate of sea level rise to increase during the next 100 years, which would submerge Galveston and other bay-front communities in 4.9 feet of additional water, Yoskowitz said.
“If you look at our topography along the Gulf Coast, it doesn’t take much of a rise for that water to really work its way inland,” he said.
At almost 5 feet, water would cover almost all of the island, except for a small strip along the seawall, according to models created by Yoskowitz and fellow study authors Jim Gibeaut and Ali McKenzie.
In Galveston County, 93 percent of households would be displaced by the rising water, according to the study.
At even the more conservative 2.3 feet, much of the West End would be underwater, and 78 percent of Galveston County households would be displaced.
Misleading Data?
But the water in and around Galveston Bay is not rising anywhere near that fast, said John Anderson, an oceanography professor at Rice University and author of “The Formation and Future of the Upper Texas Coast.”
Scientists who have worked on the Intergovernmental Panel on Climate Change agree, based on data from around the world, that the sea level is rising at a rate of about 1.6 feet, Anderson said.
The rate probably appears higher at Pier 21 because of localized subsidence, he said.
Yoskowitz and his team based their analysis on the tide gauge at Pier 21, which shows the water has risen 2.3 feet in the last 100 years.
But tide gauges are notoriously unreliable, Anderson said.
The tide gauge is mounted on a pier, and geologists agree that unnatural compaction, which would cause the gauge to slowly sink, is common where piers are installed, he said.
And based on the measurements of subsidence collected by his students between the Bolivar Peninsula and Freeport, the land around Galveston Bay sank only minimally during the last 4,000 years, which makes him even more dubious about the Pier 21 data, Anderson said.
“You can’t just take one data point and extrapolate sea level rise from that,” he said. “It’s been done, but it’s not acceptable.”
Very Slowly Sinking
Despite Anderson’s assertion that Galveston Bay area subsidence has been minimal, some area homeowners found out after Hurricane Ike their houses were not as far above sea level as they thought.
After the storm, many homeowners ordered new elevation surveys of their property, trying to figure out whether they were above the 11-foot base flood elevation established by the Federal Emergency Management Agency. Houses above the base flood elevation could be repaired without having to be raised.
Although many houses were closer to sea level than their owners thought, the problem is bad data, not sinking sand, said Tom Michel, deputy general manager of the Harris-Galveston Subsidence District.
“The best I can say is that the data out there could be as recent as last month’s data or as old as World War II,” he said.
Between 1906 and 2000, the areas around Galveston Bay sank between 1 foot and about 6 feet, with most of the drop occurring before 1975. But since then, when area governments stopped pumping groundwater out of wells, subsidence has slowed to almost nothing in most areas around Galveston Bay, Michel said.
Increased Flooding
According to federal floodplain data, the island’s east end is about 6 feet above sea level. At its highest points, areas artificially built up, the ground rises to about 12 feet.
As the sea level gradually rises, street flooding during heavy rains, like the ones that plagued the area this spring, will get worse.
Even high tides could regularly fill the streets as the bay creeps into the storm drain system.
But Galveston County residents should be most worried about the contribution sea level rise will make to the next 100-year storm, Yoskowitz said.
Using modeling software created by FEMA, Yoskowitz and his team simulated a Hurricane Ike-like scenario, which would have caused another $1.7 billion in damage in the three counties that surround the bay, if sea level was 2.3 feet higher than it is now.
With another 4.9 feet in height, the gulf’s crashing waves would easily have cleared the seawall during Ike, flooding would have spread farther through neighborhoods, and the houses closest to the bay would have been completely submerged.
Damage to the West End of the island during such an event could make the entire area unavailable for future development, Yoskowitz said.
Not That Far Off
But Yoskowitz’s predictions are a worst-case scenario, Anderson said.
“I’m just trying to go with the scientific consensus,” he said. “I tend to get a little bit upset when people overly exaggerate because then we get accused of being alarmist. We have to be very cautious in what we tell the public.”
The A&M sea level rise study was commissioned by the Environmental Defense Fund, an organization that advocates for solutions to environmental problems.
The goal was to bring local perspective to an issues that is often discussed in terms of its global effect, Yoskowitz said. The study’s authors said they hope to make people see what is happening in their own backyard.
The study recommends area governments should start making plans for protecting facilities like wastewater treatment plants from the rising water.
Area residents also need to start thinking about the implications and the overall contribution they make to climate change, starting with the amount of carbon dioxide their activities create, Yoskowitz said. And everyone should realize 100 years stretches only into the next few generations, which is not that far off, he said.
“People have to look beyond themselves, which is tough for us to do as humans,” Yoskowitz said. “It’s hard for us to think too far in the future. But we have to start thinking about what type of place we want to have for our children, grandchildren and beyond.”
