The graph, X-axis GNP, Y-axis SO2, indicates increasing function for low GNP and decreasing function for high GNP. It is reverse "U" and called "The Environmental Kuznets Curve".
In this meaning, increasing of GNP is good for the environment. But CO2 does not indicate such curve, so we cannot increase GNP without consideration. And original curve may have complex condition.
For "decreasing", one says "The reason is scaling merit." The other says "When we have enough cloth, food and house, we consider environmental action." But I do not understand the truth of this curve.
The Environmental Kuznets Curve needs attention to use. But it is interesting to make political action. And this is good reference to use various Indexes of Economical Assessment