That is assuming humans will live 80 years like they do now. Hopefully in next 100 years we'll figure out a way to increase human lifespan enough to keep expone

That is assuming humans will live 80 years like they do now. Hopefully in next 100 years we'll figure out a way to increase human lifespan enough to keep exponential growth of total population. (Some people believe that it is possible http://www.sens.org/ http://www.sens.org/)