- Global Warming and Tidal Rise in the Upper Keys - [This section is under construction] By Jerry Wilkinson July, 2009       The new buzz words seems to be Global Warming and Tidal Rising. Actually, it probably began with Rachel Carson's book, Under the Sea Wind, in 1941 published by Simon & Schuster. My research shows it becoming a subject of considerable discussion in the Key in the early 1960s as a result of studies and exploration of the major petroleum companies in the Keys areas - primarily the Shell Oil Company. I say the Keys,  but by far the majority was in its off-shore waters. Back in 1983, Hoffman. Keys and Titus in an U.S. E. P. A  study forecasted the tides to rise from 1.4 to 2.2 cm for the next 100 years. Multiply cm by 0.3937 for inches which would be an average of about three quarters of an inch per year or slightly over six feet in 100 years. Even using he lower rate of 1.4 cm would equate to about 55 inches or four and a half feet.  This would mean that Stock Island, most of Big Pine and Lower Matecumbe Key are under water. Ocean Reef would also be, but they have filled many  of residential lots to meet FEMA codes. All the access highways would however be under water. In general it could be generalized that the Lower Keys would cease to exist. According to D. M. Robbin in 1984 in Environments of South Florida, Past and Present, a study of data from the past 8,000 years revealed that the sea level has risen an average of 11 cm (4.33") per 100 years. Over the 8,000 year period this would equate to a 28.9 foot rise.  For reference, this would have been the Archaic Period (8,000 b.c. to 750 b.c.) for the Paleo Native American Indian period.         At the present for historical use I use  figures from a Bob Carr archaeological report for which credits a 'Scholl-1967.' For younger archaeological sites such as ours in the Upper Keys, 3,000 years ago (BP) to present use 3.5 cm per 100 years. For older Florida sites between  6,000 to 3,000 years ago use 2.54 cm per 100 years.         Now for the future - A 2009 report from a "international climate panel" report given at Marathon predicted a best-case 17.8 cm (7 inches) rise and the worse case as 59 cm ( 23.2 inches) rise for the 21st century.        Before I move on to maps depicting results of a  one meter (39 inch) rise at selected areas I suggest that one might visit the Internet for more predictions. Starting with "Wikipedia" at http://en.wikipedia.org/wiki/Sea_level is as good as any but do not suggest that it is final! Then one editorial statement - the sea level has been rising for about 26,000 years, yet 100,000 years ago one could have walked to Molasses Reef.       First, the seas will not just rise in the Keys, or just  in Florida - for certain it will rise through out the Northern Hemisphere - and since water seeks its own level it will rise to some extent around the globe. Secondly, when we address 100 year increments please look back just one increment to say 1910 compare history.         The following presentation is from an abstract of LIDZ, B.H. and SHINN, E.A., 1990, Paleoshorelines, Reefs, and a Rising Sea: South Florida, U.S.A., Journal of Coastal Research, 7(1), 203-229 Fort Lauderdale, ISSN 0749-0208, published by U.S. Geological Survey, Center for Coastal Studies, 600 4th St. South, St. Petersburg, FL 33701, U.S.A. This is a valuable document, After the introduction, first are shown charts of the Keys shorelines 8,000 years before present, then  6,000 years and then 2,000 years - a great primer of how the Keys developed. The last part are charts showing the Keys after one meter of sea level rise, then charts of 2 meters, 3 meters, 4 meters and 5 meters rise in sea level. The conclusion is all vestiges of the Keys will be under water with a 5 meter rise.       Space allows for most of the charts to be presented, but the idea should established.  At the five-meter sea rise only five peaks will survive: Solares Hill, Lignum Vitae Key, Windley Key and two on Plantation Key. I will work from south to north. The method used is the present island or islands are outlined with dotted lines, unfortunately these are very light in contrast, so look closely. When I do include selected depths other than one meter, the dotted lines show the change from the previous depth and not the original shore line. Click on a chart to enlarge to its original size. The areas shaded in black will be above sea level. In the publication all five levels are shown for comparison - I am only showing a one meter (39 inch) increase - even using the worse-case scenarios, these areas will exist. These charts do not consider the approximately two to three foot lunar tides, or storm surges, or wind driven waves on top of a storm surge. Lets try one beginning with Key West and Stock Island.          Lets remember that this is from a 1990 publication, but the islands profiles  have not changed that much in 19 years. All of Stock Island is gone at 2 meters. This is true for the remaining Lower Keys. Only one spot on Sugarloaf and Cudjoe Keys survive. There is a speck on Cudjoe that survives at 3 meters. All the surrounding area of Solares Hill at Key West survives 2 meters, the principal top of Solares Hill remains at 3 meters, the very top at 4 meters and a tiny speck at 5 meters.          Moving northward from Key West is a chart of the Big Pine Key area. There will be a lot of blank space between charts from here on, especially beginning with a portrait shaped chart. I could have skipped this one but the authors took a whole page for this illustration, so here it is. There are major implications to what will happen to the much loved Florida Keys off shore reefs.  Lidz and Shinn discuss the changes to come as the present Outer Reefs die because of increasing water depth (loss of photothensis and cooler water) and the present Inner Reefs take their place. It will not be a linear change as the present Outer Reefs have the extremely deep and steep slope of the Continental Shelf upwelling waters. They assume that the shelf will not change drastically. - - - - - - - - - - -          Now for the Middle Keys. It is clear that the other than the airport, the southern part of Marathon is the highest. I am not certain whether this was filled - it appears so - or if it was a ridge. The northern Middle Keys is on the smaller chart over Key Vaca. These are the only two charts in the booklet.    - - - - - -        Now to the Upper Keys again from south to north  beginning with Lower and Upper Matecumbe Keys. Lower Matecumbe Key basically disappears after a a one-meter sea rise. Like most of Key Largo, Upper Matecumbe is a ridge. - - - - - - - - - -         More Upper Keys of Windley and Plantation Keys: The four and five meter rises are not given, but the quarry area will be last to to submerge. - - - - - - - - - - - -     I will break Key Largo into three parts - Southern, Middle and Northern - southern Key Largo shown first. There is significantly high knoll  in the Harry Harris Park area. Note that it survives even a four-meter rise in sea level - - - - - - - - -  Middle Key Largo: - - - - - - - - - - - - - - North Key Largo, Angler's Club and Ocean Reef: - - - - - - - - - - - - - - - - -      Elliott Key: - - - - - - - -       NOAA does have a web page on sea level at: http://co-ops.nos.noaa.gov/sltrends/sltrends.shtml Sources: Land from the Sea by John Edward Hoffmeister, 1974; Geology of the Florida Keys by Eugene A. Shinn, Oceanus, 1988 and Paleoshorelines, Reefs, and a Rising Sea: South Florida, U.S.A. by Barbara H. Lidz and Eugene A. Shinn, 1990. Additional reading: Rachel Louise Carson (May 27, 1907 – April 14, 1964)     "Under the Sea Wind" , 1941, Simon & Schuster,     "The Sea Around Us", 1951, Oxford University Press     "The Edge of the Sea", 1955, Mariner Books,     "Silent Spring", Houghton Mifflin, 1962 -----End----- Use the back arrow to return to Keys Geology