The Reference Frame: iMatter: Your house is uninhabitable for most species

The warming induced by the increase from 391 ppm to 500 ppm is smaller (by about 20%) - because of the logarithmic law - than the warming by the same 109 ppm between 282 ppm and 391 ppm which was about 0.7 °C and pretty much unnoticeable without accurate gadgets and contrived statistical methods.