Some politicians have argued that a CO2 concentration as high as 450 ppm would be safe, under the assumption that it would lead to an increase of only 2°C (3.6°F) in the average global temperature, and that the consequences might not be so bad. There is, in fact, very little scientific evidence to link 450 ppm with a 2°C increase or to say that such an increase would be safe. On the contrary, there’s plenty of evidence that a 2°C increase would be costly and dangerous, and might even trigger catastrophic tipping points. We pointed this out in our piece.
