Source: BBC News
quote: Second, 400ppm is normal FOR THE FCKING DINOSAURS, not for humans. And CO2 2500ppm?? Dude, are you kidding me? That was 600 fcking million years ago! You couldn't even breathe the air that long ago. It was toxic to modern animals. Animals of the of the quaternary period evolved with 250-300 PPM CO2. Boost it above that and you're putting entire ecosystems at risk.