As was pointed out in a Nov. 21 letter to the editor, Earth has been warmer than it is now, so how is the current warming any different? The past warmings were caused by either well-understood variations in Earth’s orbit around the Sun and/or wobbles in Earth’s tilt, or by emissions of carbon dioxide and methane, usually from widespread volcanism. Today’s temperature rise comes at a time when the cycles in Earth’s orbit and tilt should not be warming Earth, and there is no widespread volcanism. Man’s activities are causing the warming.
Also, in the past most global warming was gradual, taking thousands of years. This gave the animals and plants time to adapt. When the Earth did warm quickly, the events were almost always highly destructive for life. Sometimes there were mass extinctions, such as at the end of the Permian geologic period when 96% of marine species and 70% of land vertebrate species went extinct. According to online information from NASA, the current rate of warming is similar to past rapid, disruptive warming events and 20 times faster than the warming caused by natural cycles. This is true, and it is a cause for concern.
Article Credit: wcfcourier