Faster than Exponential Growth
One of the commonest environmentalist cliches is that exponential growth will exceed any other kind of growth. Environmentalists will then go on to claim that population grows exponentially (unless they're put in charge, of course) and resources won't. I see no reason why economic growth must be limited to linear or other polynomial rates. It might even grow according to Ackermann's function (currently being discussed at The Corner) or even the Busy Beaver function.
The really annoying phenomenon is that environmentalists assume that anybody who disagrees with them hasn't heard of exponential growth.