Dr. Dennis Meadows , coauthor of Limits to Growth  and its updates, recently gave a talk for the Population Institute on economics, population, and the repercussions of depleting finite resources.
You can see a video of the talk by subscribing to the Population Institute podcast on iTunes  and downloading “Economics and Limits to Growth.”
Gail the Actuary summarized the presentation for The Oil Drum:
The reason I [Dr. Meadows] am giving this talk is because I think that there is the possibility of positive change.
Much of the way that we conduct ourselves is based on habit. For example, we get into the habit of crossing our arms with our right hand (or left hand) on top. It is not that putting the right hand or left hand on top is better or worse. We have just developed a habit of crossing our arms in a particular way.
If we are going to solve the population problem, we need to learn new habits. I am hopeful that like learning to cross our arms in a different way, we can inspire people to learn new habits that will limit population growth–something that is needed with finite resources.
My [Dr. Meadows’] views regarding what is sustainable are different now than they were 40 years ago. At that time, I worked with others at Massachusetts Institute of Technology to build a simple computer model that might offer some insight into the impact of limits to growth. We did not expect the model to be predictive–only that the scenarios might provide a rough boundaries regarding what might happen in the future.
In our reference scenario in 1972, we expected growth to continue for 40 to 80 more years. The major difference I see in looking at the situation now is that things seem to be developing more rapidly than we expected then.