Is catastrophic flooding coming soon to Florida? And looking further into the future, could the observed rapid melting of the West Antarctica ice field result in a catastrophic twenty meter rise in sea levels throughout the world? A number of the scientists attending the American Geophysical Union (AGU) Fall Meeting in San Francisco during December offered sobering evidence that global warming will give rise to these and other worrisome seawater threats in the future.
Held each December at San Francisco’s Moscone Center, around 25,000 of the world’s leading scientists review their findings in the fields of earth and space science. More than 23,000 abstracts, scholarly talks, and poster sessions deal with topics as diverse as Mars landers and arctic ice loss.
Continuing a trend, a large percentage of this year’s presentations focused on topics related to global warming and climate change. In the wake of the IPCC Fifth Assessment Report (AR5) which warns that the planet is experiencing “robust multi-decadal warming,” the AGU scientists’ findings lend urgency to evidence that Miami and much of southern Florida is being invaded by the ocean.
At a press conference entitled, “The Waters they are Arising,” Jayantha Obeysekera of the South Florida Water Management Agency described how king tides now routinely cause “sunny day flooding” in South Florida. Even on days without rainstorms, higher tides due to rising seas now push seawater up through the storm drain system to flood roads in Miami and other areas. Florida’s coastal water control structures, water gates meant to open after rains to drain fresh water canals and avoid flooding, now often cannot be opened because doing so results in seawater flooding inland. Unable to drain the canals by opening the gates, authorities have installed expensive high volume pumps to pump canal water up and over the structures and into the ocean. The region also faces other costly remedies to forestall ever increasing destruction of public and private properties. According to scientists, even a one degree rise in global mean temperatures, far below current scientific estimates, will lead to the inundation of much of South Florida.
In an attempt to save billions of dollars in property values, local authorities are starting to imagine the unimaginable. Previously, Holland and other places suffering from ocean flooding have built levees to hold back the seas. Unfortunately, Miami sits on porous limestone, so constructing levees to hold back rising seawaters only results in water seeping underneath the barriers. Engineers are considering building deep underground walls filled with grout to stop seepage, along with above ground barriers. Such plans may hold off waters for thirty or forty years, but will not forestall the total two to four feet of sea level rise projected during this century. Individual communities in Florida are attempting to implement local plans to deal with the threat. Some have proposed not allowing first floor occupancy of residential buildings.