Our beautiful Fripp Island is the most seaward island of South Carolina. One must travel across 4 other islands to reach it. Our three miles of beach faces the southeast, and many have been lucky enough to find spectacular sea shells or watch loggerhead sea turtles hatchlings race for the waves. Behind our island is a tremendous marsh with winding tidal creeks, endless Spartina grass, and jagged oyster beds. Those of us that live here are no strangers to the spectacular tides, and many guests marvel at how the shorelines change throughout the day.
The tides truly are the most constant, yet always awe-inspiring natural wonders we have on the island. Any outdoorsy-islander has a favorite tide chart that is checked daily to assure the best times for fishing, crabbing, kayaking, and beach lounging. The rising and falling of the tides governs our daily activities and have slowly shaped and nourished our island for thousands of years. But, what exactly causes the tides, and more importantly, why have they been so high recently?
Before understanding our recent king tides, which caused flooding all over the island and nearby areas, let’s talk about our daily, normal tides. Our moon is large enough to exert a gravitational pull on our planet, and we see that every day in the rising and falling of the tides. As the moon revolves around us, it creates a bulge of water that it pulled around the earth. If you open a tide and moon chart online (http://dickens.com/Fripp/xtide/fripptidetoday.html) you will see that a high tide is normally pretty close in time to (usually a little after) when the moon rises and then again when it sets, with low tides in the middle. A “lunar day” 24 hours and 50 minutes, therefore the moon’s position and the tides change time every day by being 50 minutes later than they were the day before. Confused? This video helps: http://oceanservice.noaa.gov/education/kits/tides/media/supp_tide05.html
The Port Royal Sound area of South Carolina’s low country experiences some of the greatest tide differentials on the Eastern seaboard. We normally
see a difference of 8 feet between low and high tide, while areas of Florida and North Carolina may see a change of just 2 feet! Think of the coastline between the tip of Florida and North Carolina’s Outer Banks. As the bulge of water pulled by the moon travels east, all that water gets channeled into a smaller and smaller area, with the focus being the Georgia-Carolina barrier islands. The amazing flora and fauna of our salt marsh is perfectly adapted to this daily change. The Spartina grass that stretches forever into the marsh is the ONLY plant (and yes, it flowers!) that can withstand being covered in salt water twice a day, every day. Our brown-green marsh water gets its color from all the organic materials and plankton, which with every falling tide is flushed out to nourish our coastal oceanic animals and plants. Our salt marsh rivals the tropical rainforests when it comes to photosynthesis and overall biological output, all thanks to our awesome tides!
So, what makes the tides get REALLY high? Every two weeks or so, the high tides near our full and new moons are generally a little higher than the rest of the month. This is due to the fact that the sun, moon, and earth are all in a straight line, creating the greatest gravitational pull on the ocean’s water. Hurricane Joaquin happened right on the heels of a full moon, and the flooding at the end of October was close to a full moon. Another factor is nor’easters, storms that generate over the Atlantic and blow in from the northeast. Hurricanes and nor’easters can often push additional water towards our shore.
Sea level rise is making these king tides more dramatic than in the past, and they are a glimpse into the every-day high tides of the future. If you ever spot a dead, standing tree in the marsh, that is evidence of sea level rise. Over the past 20 years, the ocean has risen 0.13 inches per year (http://ocean.nationalgeographic.com/ocean/critical-issues-sea-level-rise/). Climate change is certainly a natural force, but human activity is speeding up the process. It seems like a daunting challenge, but slowing climate change is a possibility if everyone makes a few changes in their lives. Being efficient with water and electricity, recycling, and getting a tune up for your car are all little ways to help. Visit http://www3.epa.gov/climatechange/wycd/ to learn more about how you can make sustainable choices. Fripp Island isn’t going to get washed away anytime soon, but I’m certainly hoping my great-great grandchildren will have enough to drive a golf cart on!
- Jessica Miller, Head Naturalist, certified hippie, and animal whisperer, can paint with all the colors of the wind