Labels:bulletin board | reckoner OCR: The ice cores have shown that sustained natural rates of worldwide temperature change are typically about one degree c per millennium. These shifts are still significant enough to have radically altered where species live and to have potentially contributed the extinction of such charismatic megafauna as mammoths and saber toothed tigers. But a most extraordinary story from the ice cores is not the relative stability of the climate during the past 10 000 years. It appears that during the height of the last ice age 20 000 years ago there was between 30 and 40 percent less carbon dioxide and 50 percent less methane in the air than there has been during our period the Holocene This finding suggests positive feedback between carbon dioxide methane and climatic change The reasoning that support ...
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