A Victoria environmental activist was quoted in the Times Colonist in January as saying he is trying to prevent "the demise of the planet." No less a figure than UN Secretary-General Ban Ki-Moon said, at the Bali environmental summit in December: "One path leads to a comprehensive climate change agreement, the other to oblivion. The choice is clear."

Is it? Are we heading for the "demise" of the planet, to "oblivion," if carbon dioxide levels go up much beyond their current level of 380 parts per million, or if the global temperature goes up three or four or five or, for that matter, 10 degrees from its current average of 12 degrees Celsius?

If this was true, then the planet and all its denizens would have died out many times in the past because levels of carbon dioxide and the global temperature have been much higher than today for most of the past 600 million years.