Outlook grimmer on South Florida sea levels

Most people don't envision what this really means. Since in most places, the land slopes up gradually from the shore, this means the water will come inland much farther than 6 feet.

If the land rises one foot for every 3 horizontal feet, a six foot rise in sea level would mean the water would come in 18 horizontal feet, 19 feet measured on the surface of the land. And that's a fairly steep rise in the land. It would be worse for a more shallow rise in land.

http://www.sun-sentinel.com/local/broward/fl-new-sea-rise-projections-20151108-story.html

Ken Kaye Reporter Sun Sentinel
Nov. 6, 2015

The outlook for South Florida's rising sea levels has turned potentially catastrophic, as new long-term projections estimate the ocean will be six and a half feet deeper by 2100 under a worst case scenario.

The Southeast Florida Regional Climate Change Compact, consisting of Broward, Palm Beach, Miami-Dade and Monroe counties, calculated that seas could rise 31 inches by 2060, about two inches more than was estimated five years ago. It predicted seas up to 46 inches higher by 2075, enough to submerge a large chunk of coastline.

Even if seas rise three to five inches, which is expected within the next 15 years, South Florida would face a range of hardships, from endangered drinking water supplies to a degradation of public services.

"What we'll see is systematically more flooding, deeper flooding and more pervasve flooding – and with lesser events," said Jennifer Jurado, Broward County's director of natural resource planning and management. "It will take less in the way of rainfall before you flood."

Long-range predictions, which previously hadn't extended to the turn of the next century, call for the sea to rise 78 inches at an accelerated rate. If the projections hold, much of this region would be underwater within the next 85 years unless greenhouse emissions are sharply reduced, the steady rise of the Earth's temperature is stopped and arctic ice stops melting.

Jurado said evidence of the increased flooding can already be seen with heavy rains and King tides, particularly in the coastal areas of West Palm Beach, Delray Beach, Fort Lauderale, Hollywood and Miami Beach.

Other major impacts, some of which already are being seen:

• Increased sand and soil erosion, leading to more coastal flooding;

• Increased inland flooding, including areas west of Interstate 95, as a higher ocean would disable the stormwater drainage system;

• Saltwater intrusion in the Biscayne aquifer – South Florida's primary freshwater supply – and local water supply wells;

• Increased pollution on land and in sea, the result of debris and hazardous materials released by flooding;

• Higher flood insurance premiums.

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The projections paint a much bleaker picture than was depicted in an earlier report compiled by the Intergovernmental Panel on Climate Change, a United Nations sanctioned body, Jurado said.

"They had absolutely failed to intergrate ice melt in the projections," she said. "So everybody knew it was really conservative."

Because of the uncertainty of how fast the seas will rise – and how much greenhouse gases will be curbed – the Compact predicted a wide-range of possibilities.

Specifically, it calls for sea levels to rise 3 to 5 inches by 2030, 8 to 31 inches by 2060 and 19 to 78 inches by 2100.

Although much of the globe will be subject to the same sea level increases, the fear is that South Florida will be particularly vulnerable to flooding because of its low level and because of strong ocean currents that run nearby, such as the Gulf Stream.

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There is strong evidence those emissions are causing an alarming increase in global temperatures: 14 of the 15 hottest years on record have occurred since 2000. This year likely will be the warmest year on record, "with 2016 a good bet to exceed even 2015's warmth," said Jeff Masters, director of meteorology for Weather Underground, the online weather site.

Further, greenhouse gas emissions nurtured several extreme climate events in the past year, including a highly active hurricane season in the Eastern Pacific, drought in East Africa and stifling heat waves in Australia, Asia and South America, the National Ocean and Atmospheric Administration said.

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