Essays on global warming and climate change
Global warming is the greatest challenge facing our planet
For several million years, life in the Eocene was halcyonic, and at 50 mya, the state had prevailed ever since the 250 mya. But just as , Earth began cooling off. The ultimate reason was atmospheric carbon dioxide levels that had been steadily declining for tens of millions of years. The intense volcanism of the previous 200 million years waned and the inexorably sequestered carbon into Earth’s crust and mantle. While falling carbon dioxide levels were the ultimate cause, the first proximate cause was probably the isolation of Antarctica at the South Pole and changes in global ocean currents. During the early Eocene, the global ocean floor’s water temperature was about 13oC (55oF), warm enough to swim in, which was a far cry from today’s near-freezing and below-freezing temperatures. The North Sea was warm as bathwater. Radical , warming the ocean floor, and . Whatever the causes were, the oceans were warm from top to bottom, from pole to pole. But between 50 to 45 mya, Australia made its final split from Antarctica and moved northward, India began crashing into Asia and cut off the Tethys Ocean and the global tropical circulation, and South America also moved northward, away from Antarctica. Although the debate is still fierce over the cooling’s exact causes, the evidence (much is from ) is that the oceans cooled off over the next 12 million years, very consistently, although a brief small reversal transpired at about 40 mya. By 37-38 mya, the 200-million-year-plus Greenhouse Earth phase ended and the transition to today’s ice age was underway. In the late Eocene, as the trend toward conditions began, such as the .
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In Paleocene oceans, sharks filled the empty niches left by aquatic reptiles, but it took coral reefs ten million years to begin to recover, . As Africa and India moved northward, the shrank, and in the late Paleocene and early Eocene, one of the last Tethyan anoxic events laid down Middle East oil, and the last Paleocene climate event is called the (“PETM”). The PETM has been the focus of a great deal of recent research because of its parallels to today’s industrial era, when carbon dioxide and other greenhouse gases are massively vented to the atmosphere, causing a warming atmosphere and acidifying oceans. The seafloor communities suffered a mass extinction and the PETM’s causes are uncertain, but the when the global ocean warmed sufficiently is a prominent hypothesis. Scientists also look to the usual suspects of volcanism, changes in oceanic circulation, and a bolide impact.