We already did. Those numbers represent the area under an exponential growth curve with respect to time as the curve approaches a global energy maximum carrying capacity. In other words, it shows the globe filling up just before catastrophic collapse or a mass die off. It is unclear what the post collapse stability level will be (before the Industrial Revolution the stable population level was less than a billion). We don’t know if the new level will be the same as pre-IR or if automation related efficiencies will increase it above the pre-IR level. We don’t know how many post collapse people could survive with horse and oxen to generate food vs biodiesel farm equipment for example.