Rising seas, climate change to impact Nature Coast

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By Mark Scohier, Staff writer


The Nature Coast will see drastic changes due to sea level rise by the turn of the century, according to a state expert at a meeting Oct. 18.

Whitney Gray, sea level rise coordinator with the Florida Sea Grant and the Florida Fish and Wildlife Conservation Commission, told an audience of about 25 people in Gainesville that conservative estimates of sea level rise of .64 meters show seas moving up to 3.7 miles inland for areas near Waccasassa Bay and for much of the state, thanks to a relatively flat terrain.

“Now, even a meter of rise by 2100 is not at all an extreme prediction,” she said, adding that there is, however, a degree of uncertainty within various models that try to predict the future. 

People debate the extent to which human activity verses the planet’s natural cycle has in increasing global temperatures, which is at the heart of the matter. A warmer planet means warmer seas, which has the effect of increasing water volume. It also means there’s less water locked up in the frozen regions of earth. According to the National Oceanic and Atmospheric Administration, last month saw the largest melt of Arctic ice since scientists started keeping tabs, shrinking to a record-breaking 1.32 million square miles.

What’s less of a debate, Gray said, is what scientists know about the history of rising seas, which have been recorded as far back as the 1860s with sea level gauges and, more recently, with satellites. From the early 1990s to 2010, sea levels increased by about 3 millimeters, or, as Gray explained, about the thickness of a Kraft Single. In the last 100 years, the planet’s oceans have seen about a 9-inch increase.

“I haven’t calculated how many slices of cheese that would be.”

Gray, whose focus is on how sea level rise will affect coastal ecologies, said people can expect to see big changes in the natural systems in places such as Cedar Key. Coastal and even inland forests will turn into salt marshes, she said, having an impact on wildlife refuges and state parks in the area.

“Do we move the boundaries of a state park? Does it become an underwater state park … .These are the discussions we have to have.”

On the Nature Coast, sea grass, which prefers to grow at certain depths, will also be affected, she said. And animals such as scallops depend on sea grass.

Oysters could take a hit, as well. In February, scientists with the University of Florida said oysters in Cedar Key and the Big Bend area had suffered a 66 percent decline due to the reduction in fresh water coming out of the Suwannee River. Higher salinity levels and warmer temperatures increase the chances that disease and predation will have a negative effect.

In recent weeks, the industry has seen massive die-offs, thanks in part to disease attributed to higher salinity levels that weakened the mollusks, a scenario expected to get worse as climate change increases both water temperature and salinity levels through rising seas.

Animals such as the much-coveted manatee, finding that habitat or sources of food have disappeared, may be forced to live in other places. In fact, Gray said, humans are sure to have more conflicts with wildlife as habitat shrinks.

Other effects include increased vulnerability from storm surge, shoreline erosion, changes to tidal patterns, increased flooding and saltwater intrusion—a nasty side effect Cedar Key residents have already had to deal with but that also impacts certain plant populations.

Toward the end of the meeting, a man from the audience asked, “We’ve had this sea level rise. What is going to stop it?”

Gray responded by saying it would take a massive reduction in greenhouse gasses in the planet’s atmosphere.

Most greenhouse gasses, such as water vapor, methane, nitrous oxide and carbon dioxide, occur naturally in the atmosphere, though human activity produces them as well. In the U.S., according to the U.S. Energy Information Administration, most U.S. manmade greenhouse gasses, about 82 percent, come from the use of petroleum and natural gas.

Radiation from the sun passes through greenhouse gasses on its way to earth but is absorbed by those same gasses before it can be reflected back out into space, which, in the past, has kept the planet warm enough for life to survive. But get too much gas, and the planet gradually gets warmer, impacting places like the Arctic where ice continues to shrink each year. The ice in that region, mostly Greenland, also continues to get thinner and saltier, according to the NOAA, which makes it easier to melt when it breaks off and floats through warmer areas of the northern seas.  Scientists attribute this to altered wind and ocean currents brought on by warming temperatures.

To complicate matters further, shrinking ice means less radioactivity from the sun gets reflected away from the planet’s surface, making the planet warmer still and manipulating wind and ocean currents even more.

A few years ago, scientists discovered that the planet has warmed enough to allow permafrost, grassy regions frozen for thousands of years, to begin thawing, which could release millions of metric tons of ice-trapped methane from decaying vegetation into the atmosphere.  

Such factors, which pop up every few years, are why Gray says predictive models once viewed as “extreme” fall more into acceptable ranges of what is likely to happen.

But, though people can prepare for a changing world, there’s not much to be done to stop it from happening in the near future, Gray said. 

“The amount (of greenhouse gasses) there now will not go away for several hundred to a thousand years,” Gray said. “So, we have a situation, and what we do will help address it for future generations.”