Rising sea raises concerns

The Brunswick News

By Nikki Haley
January 20, 2012

As scientists predict that sea levels will continue to rise during the next 100 years, some are urging that measures be taken now to lessen the effects of rising water.

The sea level along Georgia’s coast is rising at a rate of 3 millimeters (0.11 inches) per year, about a foot per century, and that’s expected to continue to increase over the next 100 years, said Clark Alexander, professor at the Skidaway Institute of Oceanography. A sea level that has risen at a constant rate the past 70 years is predicted to double its rate during the next 100 years, Alexander said. “The rate is going to increase, and it’s going to increase significantly,” he said.

“Sea level rise is an ongoing thing and it’s real. It’s been going on for a long time, thousands and thousands of years. The shoreline is not a static boundary. It is a dynamic boundary that is always moving,” Alexander said.

Melting arctic ice caps and rising ocean levels could have significant consequences for the Georgia coastline, including receding marshlands, flooding and greater storm impacts. “It is the million dollar question that every coastal community is asking themselves: ‘What can we do if sea level rises and we start experiencing these impacts?’” Alexander said.

Jennifer Kline, coastal hazards specialist for the Coastal Resources Division of the Georgia Department of Natural Resources, works to prevent and plan for the effects of coastal hazards, including higher sea levels. She says planning where critical structures, such as hospitals, schools, roads and evacuation routes are placed is an important part of preparing for the effects of rising sea levels. Strategic planning for structures may also prevent marshlands, usually forced out by rising oceans, from receding, Kline said.

The effects of a rising sea level have been seen already along the Georgia coast. Higher ocean levels lead to increased flooding, Alexander said, allowing storms to reach farther inland. “If the tide was at 5 feet 100 years ago ... the waves on top of the storms didn’t reach your house, but now the tide at high tide is 6 feet, and that allows those waves to get over your seawall or dunes,” he said.

Flooding related to a higher sea level also leads to reduced capacity in storm water drainage systems. Alexander says this has occurred in Savannah, where the system was laid down in the 1800s and is no longer able to keep up with high ocean levels. “Now that sea level is a foot or two higher than it was when Savannah designed its system, when the tide is in, it fills up a bunch of pipes so there’s nowhere for the water to go,” Alexander said.

Groundwater aquifers have seen salt water intrusion, instances in which salt water invades fresh water aquifers, as a result of a high ocean level. The best prevention for salt water intrusion, Kline said, is water conservation that reduces the amount of fresh water taken from the aquifer. “Water conservation is something we can be doing now to kind of prevent that effect,” she said.

While there are steps that could be taken to lessen short-term effects of a rising sea level, little can be done to prevent long-term effects, Alexander said.

“You can stabilize the shore for some time period, but, in the end, sea level rise, when it gets high enough, will beat those kinds of protections,” he said.