The name comes from the number of parts per million of carbon dioxide in the atmosphere that, according to Jim Hansen, perhaps the world’s leading climate scientist, we should not exceed if we are to avoid potentially catastrophic climate change. It is a measure of the seriousness of our problem that CO2 is already at 386 ppm, and is rising by two ppm each year.
10月24日就是所谓的“350日”。而这个名字则源自于大气中每百万份之350的二氧化碳含量值，照全世界最杰出的气候科学家吉姆·汉森所说，如果我们要避免遭遇潜在大规模气候变化的话，那么大气中的二氧化碳含量就不能超出这个数。而这一测量手段也同时凸显了当前问题的严峻性，因为目前二氧化碳含量已经达到了386ppm，并以每年2ppm的速度在不断增长。