Well he's not wrong, really.
No... he's totally wrong. But even if not it is unseemly for the leader of a country to spend eight years bad mouthing his own country every time he goes abroad.
How? People usually damage the environment out of laziness, whether it being trying to reduce or take a cleaner approach rather than maliciously wanting to damage the environment.
Likewise with people being lazy about learning about the world. Lots of people in the first world are that way, as well.
Haven't got the sense he dumps on the US that much, go see a Euro talk for that.