A few substances may actually be near a limit. An example is rare earths important for electronic gear, like terbium and dysprosium, mined only in China so prices have sharply increased since 2007. In this case, conventional market signals prompt seeking other sources or substitutes. A New York Times summary can be found here.
A sneakier situation envelopes most raw materials, from tantalum to coal. Many rich old lodes have been worked out. Mining less concentrated, deeper sources tears up more property by moving more dirt using more aggressive recovery techniques. Where resources are widely dispersed, more energy is needed to obtain them, and people object to their backyard being chewed up. Examples include mountaintop coal mining, Colorado oil shale, and even uranium.
Some of the richest U.S. uranium deposits are on Navaho land. There uranium mining in the 1950s-1960s left such severe consequences that the Navaho have vowed never again. No one knows how this will play out. But uranium is not an inexhaustible resource either.
More dispersed or embedded resources take more energy and often more water to obtain. Examples are all around. For example, a recent controversy publicized by www.ProPublica.org is waste water from hydraulic fracturing to release natural gas from rock. Energy, chemicals, and lots of water combine to break up rock and release gas — a process that was long non-economic. Now hydraulic fracturing is alleged to let chemicals permeate water tables near fractionation sites.
Peak oil has now entered mainstream news off and on, and credible sources (amid the ranters) are easy to find on the internet. The latest issue of the The World’s Water edited by Peter Gleick (an authoritative source on global water) even broaches the possibility of “peak water.” Peak water is impossible as a global phenomenon, but in many localities fresh water is nearly tapped out.
This skimpy picture of shortages is far from exhaustive, but shortages feed on each other because a shortage of one resource limits the ability to obtain others. They add up to a resource-short future at projected demand levels using current technology.