submitted Suri Sehgal, Chair, Captiva Island Yacht Club Environmental Awareness Committee
Sea levels around the globe have fallen and risen dramatically over millions of years, driven primarily by glacial advance and retreat. Sea level changes in the distant past were often substantial and occurred faster than the incremental increase now. It will be the topic of an event hosted by the Environmental Awareness Committee of the Captiva Island Yacht Club at 10:30 a.m. Tuesday, Feb. 11, at CIYC, 15903 Captiva Dr.
After the last ice age ended approximately 18,000 years ago, the sea level rose rapidly, but the last few thousand have shown a steady rise. Lately the pace of sea level rise (SLR) has accelerated primarily due to icecaps melting into the ocean, warming ocean waters, which expand when warm. The slowing Gulf Stream and sinking land also contribute to sea level rise in some areas.
The global warming is the culprit of SLR. The average global temperatures have already risen by 1 to 1.2 Celsius since the pre-industrial era (PIE) and continue to rise, driven by rising greenhouse gas (ghg) emissions and atmospheric concentrations of ghg. As the globe warms, so does the ocean water.
How high the sea will rise is anybody’s guess and is a subject of debate by scientists. Whether it will be a few inches or a few feet depends on the assumptions used on temperature rise. A rise in the global mean temperature by 3 degrees Celsius (or more since PIE) could trigger a rise of a few feet by the end of this century. One can’t say with certainty how fast the ocean will warm and the ice will melt. One thing that is certain is that water levels will continue to rise faster, we just don’t know how fast. Therefore scientists from the National Oceanic and Atmospheric Administration (NOAA) and the US Army Corps of Engineers (USACE) have made predictions based on ranges from low to high.
The world’s oceans are the clearest measure of the climate emergency because they absorb more than 90 percent of the heat trapped by greenhouse gases emitted by fossil fuel burning, forest destruction, and other human activities.
The mitigation of SLR requires a holistic, long-term approach with robust and meticulous long-term planning, informed investment in resilient infrastructure, adapting land use and building policies to address the climate challenge, advancing new transportation solutions, and educating and informing citizens about climate change.
The soft structures that can protect the coast from SLR include salt marshes, mangrove forests, kelp forests, etc. The hard structures include sea walls, bulkheads, revetment, etc.
If mitigation steps are not taken, the current sea level trends can lead to island and lowland submergence, desertification, stronger storms, ocean acidification, species extinction, coral reef die-offs, pressure on food supplies and the like—sowing economic disruption from massive relocation to higher grounds.