Rob Carlson participated in the Economist debate on whether computing is the most significant technology over the last century. He has an amazing infographic in that post showing the US corn crop yield as a function of time, as well as the US planted area. That diagram is IMHO one of the best environmentalist arguments for GM crops.
Thanks to crossing and ever more advanced biotechnologies yields have been increasing since the 1940s, yet still have plenty of room to go before reaching even current test limits. And the acreage needed has been declining, at least in principle allowing more space for nature.