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Ocean's rise worries scientists
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Scientific experts say the rising level of the world’s oceans is a naturally occurring event. However, what concerns them is the increase in the rate at which our coastal waters are rising. This issue affects local residents as much as it does people who live in other states along the Atlantic coast, scientists say.
Dr. Clark Alexander, a coastal geologist with the Skidaway Institute of Oceanography in Savannah, has been researching rising water levels for at least five years.
Alexander said as coastal water levels rise, the land/sea boundary is affected. New areas of coastline may be exposed to wave attacks, he said.
Also of concern, Clark added, is the warming trend of the Earth’s oceans, which is thought to contribute to the sea waters’ rising levels.
Alexander explained that sea levels have risen during the past several million years on cycles of 20,000 years – or one foot per century. This, he said, is a natural cycle.
At one time, about 18,000 years ago, the oceans were about 400 feet lower than they are today and the coastline was at the edge of the continental shelf, according to Alexander.
The Skidaway scientist said a gauge maintained by the National Oceanic and Atmospheric Administration at the mouth of the Savannah River at Fort Pulaski has been measuring water levels for 70 years. NOAA’s data currently shows a 3-millimeter rise on sea level per year. This is a relatively low rate, he said.
The issue, Alexander stressed, is what can happen in the future because of global warming.
He said the Intergovernmental Panel on Climate Change put out a report in 2007 that estimates how high the sea levels will rise during the next 100 years. The IPCC shared the Nobel Peace Prize with former Vice President Al Gore for his efforts to bring global warming to the public’s attention, the professor said.
He added that the Earth’s warming trend will melt glaciers at a faster rate and when that water goes into the oceans the waters will rise.
The significance of the IPCC’s report, Alexander said, is that most scientists now believe the higher estimates of increasing water levels appear to be more correct than the lower estimates.
“If the rate quadruples, a lot of the areas of the coast will be underwater,” he said
Alexander said scientists also expect stronger hurricanes because ocean temperatures are warming.
“There has been some analysis as well that the frequency of category 4 and 5 hurricanes is greater now than in the past,” he said.
Dr. Chuck Hopkinson, director of the Georgia Sea Grant College Program and a professor of marine sciences, said people in Liberty and Bryan counties must also ask themselves how global warming will affect their lives and the coast’s environment.
Hopkinson is a coastal ecosystem geologist who has researched watersheds, estuaries and the continental shelf. He lived on Sapelo Island for 10 years.
“The thought is that we have disrupted the natural cycle of cooling and warming because of human additions of carbon dioxide emissions to the atmosphere,” Hopkinson said. “There’s no evidence of CO2 varying at these rates elsewhere in history.”
Hopkinson explained that fossil fuels’ combustion combined with deforestation – primarily of the earth’s rainforests – is causing variations in climate change across the globe.
However, the Earth’s north and south poles are particularly susceptible to climate change, he said. Warmer temperatures at the poles are causing glaciers to melt at a faster rate.
“When water warms it expands, so it takes up increased volume,” Hopkinson explained. “So the water currently stored on land in the form of glaciers is being transferred to the ocean as the glaciers melt. When you increase the volume, all you can do is go up and out. The out is going to be affecting where people live.”
Hopkinson said people should ask, “What does climate change mean for Georgia? Is it temperature change, is it drought, is it increased storminess? Is it sea level rise? What will be felt most in Georgia?”
The next questions folks should ask, the professor said, is what is causing climate change in their state.
“Is it factories, is it home heating, is it burning gas in cars and airplanes, is it running your air conditioning?” he said.
Hopkinson said if people understand what their contribution is to carbon dioxide emissions, they can begin to discuss its ramifications and relate it to where they live.
The professor said climate change affects the area’s ecosystems, and thus would affect the benefits people gain from local ecosystems, such as fishing.
Coastal Georgia has barrier islands and the most extensive salt marshes on the East Coast, according to Hopkinson. Both help protect the land and its inhabitants against storms, but should themselves be protected, he said.
“Those salt marshes are only going to be there if the marshes can keep up with sea level rise,” he said.
Hopkinson said coastal estuaries in the marshes also need fresh water. 
“We need fresh waters getting out of our rivers to maintain the health and the habitat of the species living in the estuaries,” he said.
Hopkinson said other changes in climate, such as drought, can affect coastal ecosystems. He referred to the extensive death of marsh grass and a collapse in blue crab fisheries several years ago due in part to extreme drought.
“If the salinity (in the marsh) gets too high, it will kill organisms living in the estuary,” he said.
Hopkinson said people on the coast also should be concerned over how much water Atlanta could take from coastal rivers in the future to serve its residents’ water needs and “think of this on top of climate change.”
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