Who are you trying to protect, and from what? Why does it hurt your sensibilities when emotive language is used to describe the damage we have done? True 400ppm might not sound like much, but it is if we compare with the natural (pre-human) level of around 120 ppm. So we've increased it by more than 300 percent, with the latest doubling in the past sixty years, and on course now to hit 400 percent in maybe another ten years.
The effect of that exponentially rising jam-jar we are creating around us, is a second order exponentially rising temperature, which warrants the most emotive language we can imagine, to ram the message home that we have to stop it, and reverse it, before more harm is done, regardless of the effect on economy, which in the end affects rich folks more than anyone else, since they are the main polluters by their use of capital which has to come from energy by extraction.
Does that help explain?