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Thomas J. Goreau

Climate change in Jamaica

PROPOSAL FOR A WORLD HERITAGE SITE

March 4 2012

 125000 YEAR SEA LEVEL

 The ancient Sea Level Notch at Discovery Bay, Jamaica is 125,000 years old, and is 7 meters above modern sea levels. The sea is visible through the gap. The large rocks on the right are blocks of limestone that fell off the cliffs at that time (this can be shown by the fact that marine fossils grew on them after they fell into the water). 2009 Photo by T. Goreau showing Tracey Edwards, a marine science student at the University of the West Indies, for scale.

 This incredible site shows clearly what we are headed for: when sea level and temperature come to equilibrium with the PRESENT level of CO2, this site will be deep underwater. This location should be made a World Heritage Site by the Jamaican Government.

 After T. J. Goreau, 1965

 A geological cross section of the central North Coast of Jamaica. The solid blue line shows today’s sea level, the dashed blue line 7 meters higher (25 feet) is the sea level from 125,000 years ago, the last time global temperatures were 1 degree C warmer than today, and a significant part of the Greenland and Antarctic Ice caps had melted. At the same time London, England (and probably Copenhagen as well) was a tropical swamp with crocodiles and hippopotamuses. At that time modern humans had recently evolved, and had not yet spread out of Africa. The lower part of the fossil reefs has all the corals intact, in position of growth. Above them is thin red layer of clay washed in by large waves, and above it all of the corals were smashed to pieces by huge waves from hurricanes or tsunamis, and lie on their sides. Jamaica has not undergone significant geological uplift or sinking in this time period, the same ancient sea level can be found at sites all around Jamaica, and on many other stable oceanic islands around the world. Older sea level notches, dating from before the Ice Ages, can be seen much higher up on the cliff. If all the Antarctic Ice were to melt due to uncontrolled increases in CO2, global sea level would rise around 70-100 meters. That is where we are headed, in the long run, if we don’t reduce greenhouse gas concentrations to safe levels.