Carbon dioxide milestone

This is old news, of course, but we recently passed 400 ppm carbon dioxide in our atmosphere. The following cartoon seems to say it all (click here for full version):

Mind you, that cartoon is on an American leftie website, so among the currently 82 comments on it you will not find the usual climate change denialism that descends on every other place daring to mention the topic. But what you do find is an also fairly typical pair of defensive reactions:

1. Yeah, I needlessly waste a lot of petrol, but it is not really my fault because industry is worse.
2. Yes, our industry is a bad polluter, but it is not really our fault because China is worse.

It can be assumed that a Chinese commenter would be inclined to argue that others are still worse on a per-capita basis and that China has the right to develop.

One of the greatest impediments to solving our global problems is that people consider this type of argument to be clever: "Yes, I am doing something suicidally stupid but that guy over there does the same, so stop bugging me."