With the current discussion of global warming, visitors and residents of Costa Rica are not likely to know that the country hosted glaciers perhaps less than 10,000 years ago.
Evidence of these masses of ice can be seen mainly on the west side of the Talamanca mountains. The glaciers left deposits of rock and rubble that provided dams for lakes that exist today.
Tropical glaciers are not big areas of scientific study these days with the emphasis on the impact of global warming.
Yet several studies point out the variability of climate that contributed to glaciation.
The most recent study appears to be that of Matthew S. Lachniet of the University of Massachusetts. He reported in 2003 on how the peaks of Costa Rica contained perpetual ice during the late Pleistocene. He estimated that the tongues of ice descended to about 3,000 meters, about 9,800 feet above sea level.
The Pleistocene epoch lasted until about 11,700 years ago, certainly at a time when modern humans lived in Costa Rica.
A 1990 study by Sally P. Horn of the University ofTennessee studied lake sediment around Mount Chirripó and concluded that the glaciers retreated about 10,000 years ago. She used radiocarbon analyses of the organic matter in lake cores to reach that conclusion.
A Costa Rica research report by Roberto Protti in 1996 concluded that glaciers descended as low as 1,000 meters or about 3,280 feet elevation. He based his conclusions on deposits of giant boulders that bore scratch marks from being pushed by the ice as well as the location of moraines, the rubble left by the retreating glacier. Most of his work was based in the Valle del El General in south central Costa Rica.
Other scientists have concluded that the glaciers were contemporaries with the megafauna that inhabited the country up to 15,000 to 13,000 years ago.
These included creatures bigger than elephants with gigantic tusks, giant sloths, saber-tooth cats, cave bears, camels and hungry birds with 12-foot wingspans.
Earth scientists are not sure if the current warming trend will reverse itself and lead to another ice age, and the climate has done at least five times in the history of the world.
But a study of the glacial deposits are a sure sign that the earth undergoes great changes.