Bill McKibben [search] writes in “Civilization’s last chance” [ark] the best summing up of the known threats facing humanity now from climate change if major emission cuts are not pursued immediately. His latest campaign efforts highlight the number 350, which he calls “the most important number on Earth” because of scientific understanding that if carbon emissions are not stablized at 350 ppm, it will not be possible “to preserve a planet similar to that on which civilization developed.”

It has been noted here that at 383 ppm we are already well past this threshold, and thus achieving 350 ppm will require gargantuan efforts if we are to survive much less prosper. The piece is a clarion call that long predicted limits to growth have arrived and the fate of civilization depends upon urgest massive emission cuts now, tomorrow, next year and certainly well before 2050 as is being proposed [ark | search].