If you stand on the shore at the high tide mark and look inland, the horizon (minus all the villas and trees) will be about at eye level. At five feet, the mighty peak of the island is less than the height of the average beachgoer, so the National Oceanic and Atmospheric Administration (NOAA) predictions of sea-level rise by the end of the century don’t look good for Captiva. Their curves suggest an outside chance of up to six feet of sea-level rise by 2100, while conservative estimates range from three to four feet. For sure there will be a steady, measurable and troublesome encroachment month by month, year by year. The graph outlines the possibilities and suggests some of the potential timing.
Most likely the perceived impact will be twofold–first the steady rise of the spring and fall high tides moving to the edge of the beach and beyond, damaging the road and coastal homes. Second and more dramatic will be coastal storms gaining impact because of the higher, warmer seas. And if we are unlucky, storms may create surges which overtop and engulf the island, eroding the beaches, but maybe also piling debris to add to that five feet of internal height.
As a barrier island, Captiva will tend to change form and migrate under natural conditions, probably moving toward the mainland shore. This may happen in any event but there is much that we can do to postpone or even change this scenario.
Of course we need to act, reducing emissions and finding ways to store excess carbon, methane and other greenhouse gases. Anything we can do to enhance this process, we should. But even if Captiva and South Florida could achieve zero emissions, our past actions and limited ability to respond globally mean we face ongoing global temperature rise, melting ice sheets, warming oceans and rising seas.
So while thinking globally we also need to be acting locally, especially in vulnerable places like Captiva (and nearby Sanibel where my daughter has a house!) We may not stop water levels rising, but we can lessen the impact by deferring the damage and lengthening the time Captiva remains a beautiful, vibrant part of the world.
Unfortunately, the most obvious measures– structures like sea walls and dykes–won’t work. Captiva is a gift of nature, and natural systems are the best defense for rising seas. Mangroves are wonderful shore protectors as the intricate root structures break up all but the greatest waves and at the same time provide the basic structure of a whole ecosystem of plants and animals. Natural or manually reinforced sand dunes are also excellent natural protectors. Superstorm Sandy provided an unfortunate experiment demonstrating that fact. Communities with coastal dunes were much more protected than those that had cleared the dunes to improve the view.
We can also look at the design of our houses and infrastructure. Can water flow through rather than into our dwellings?
With the presence of the Rauschenberg Residency and its low profile to the sea, Captiva can contribute to the awareness of sea-level rise in two unique ways. One is by monitoring the impacts of the rising waters and the effectiveness of the measures taken to ameliorate impacts.
Secondly, through effective communication and outreach, artists and scientists can assist in defining the problem and helping people and communities adapt and deal with it. Thus Captiva is a living laboratory for the artist and an inspiration for the scientist.