As recently noted in a post-Bali analysis, how to achieve the goal of mitigating climate change is complex, yet the goal can be explained simply.
What may turn out to be the most crucial development went largely unnoticed. It happened at an academic conclave in San Francisco. A NASA scientist named James Hansen offered a simple, straightforward and mind-blowing bottom line for the planet: 350, as in parts per million carbon dioxide in the atmosphere. It’s a number that may make what happened in Washington and Bali seem quaint and nearly irrelevant. It’s the number that may define our future.Bill McKibben — “Remember This“
It is a number that “every person needs to know,” argues McKibben. The commonly accepted level at Bali was 450 ppm. One reason for such a level is that we’re already at 383. Since we already are over the Hansen 350, does that mean we are doomed, asks McKibben rhetorically?
Not quite. Not any more than your doctor telling you that your cholesterol is way too high means the game is over. Much like the way your body will thin its blood if you give up cheese fries, so the Earth naturally gets rid of some of its CO2 each year. We just need to stop putting more in and, over time, the number will fall, perhaps fast enough to avert the worst damage.
Hansen says… the last time the Earth warmed two or three degrees Celsius — which is what 450 parts per million implies — sea levels rose by tens of meters, something that would shake the foundations of the human enterprise should it happen again.
Hey, but the cheese fries already will have done us in, so what does it matter if most of Florida goes glub, glub, glub.