365 Days of Climate Awareness 262

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Central America political map.

The academic debate swung for some time over when Central America became a complete land bridge blocking the Pacific from Atlantic waters. The consensus thought is that this led to the formation of the Gulf Stream and the current North Atlantic climate regime, in addition to the ice ages of the last 2-3 million years related to Earth’s Milankovitch cycles. Several different sources of evidence, including fossils and sediment cores from the Pacific and Caribbean, leave a fairly wide window for this to have happened, nearly six to about 2.5 million years ago. Currently, the isthmus is crossed by the Panama Canal, although this has nothing to do with ocean currents.

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Physical map of Central America.

The region is tectonically very active, with two oceanic plates – the Cocos to the north and the Nazca to the south – moving northeast and sinking beneath the Caribbean and South American plates. Volcanoes and earthquakes are regular there. In addition to this, the region frequently receives tropical cyclones, from depressions to hurricanes, on an annual basis. Despite the dynamic geological and climatic environment, Central America is one of the most biodiverse places on earth, estimated at 7% of the planet’s total biodiversity (number of distinct species).

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Central America tectonic map.

Evidence of human habitation dates back over 12,000 years. The area became dominated by the Maya from the south and the Aztecs from the north, although the arrival of the Spaniards in the early 1500s marked the era of colonial rule and the forced export of mined precious metals and other products. In the 1800s, local people began to assert their independence, though they rarely found peace with each other, and Mexicans to the north made repeated attempts to conquer and control their neighbors to the south. The modern countries we know emerged largely from ongoing civil wars and attempts at conquest that continued through most of the 19th century.

Tomorrow: climate issues in Central America.

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Köppen-Geiger climatic zones, 1980-2016.

Be brave and be well.

Sources

central America

Closure of the isthmus

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