The days of assuming natural resources can be swapped in and out to solve shortages - corn for oil, soy for beef - may be over. An international group of scientists demonstrate that many key resources have peaked in productivity, pointing to the sobering conclusion that "renewable" is not synonymous with "unlimited."
For Jianguo "Jack" Liu, who is director of MSU's Center for Systems Integration and Sustainability, this is strong reason for integration—to approach sustainability problems holistically, rather than searching for a "one for one" substitution to offset shortages.
"People often talk about substitution. If we run out of one resource, we just substitute another. But if multiple resources are running out, we've got a problem," Liu said.