Is it true the greenhouse effect of carbon dioxide does not increase by a significant amount as its atmospheric concentration increases from 300 ppm to 800 ppm, as indicated in the chart in the link below? Does it matter? Why? - T.L. Winslow

https://www.quora.com/Is-it-true-the-greenhouse-effect-of-carbon-dioxide-does-not-increase-by-a-significant-amount-as-its-atmospheric-concentration-increases-from-300-ppm-to-800-ppm-as-indicated-in-the-chart-in-the-link-below-Does-it/answer/TL-Winslow