The combination of bringing more land into production, along with the Green Revolution has allowed for the needed increases in food production to date. However, many of the lands which have been converted to farmland were marginal or sensitive ecosystems which cannot sustain repeated use. In many developed regions of the world, prime farmland is being lost due to urban encroachment and increasing land prices, while increases in population far outreach the increases in food production.
In light of the problems associated with the Green Revolution, we must continue to develop new or improved strategies for increased food production. Future limiting factors include soil degradation, over harvest of aquifers, soil salinization, climate change, available petroleum, and the social-economic issues around sustainable agriculture. Furthermore, continued reliance on Green Revolution techniques alone will not be enough to continue with the increases in food we have seen over the last four decades. It's reliance on petroleum, fertilizer and soil amendments and irrigation are not sustainable and changes must be made to continue at even a similar rate of production as oil is coming to peak oil prices and aquifers in China and the midwest are over harvested.
Norman Borlaug, the father of the Revolution, has proposed the need for varieties which will have greater tolerance for abiotic extremes, such as drought, heat, cold, as well as greater tolerance for soil alkalinity, free aluminum and iron toxicities. In his Nobel Peace Prize anniversary lecture, he suggested the need for a Blue Revolution to complement the existing Green Revolution. "In the new Blue Revolution, water-use productivity must be wedded to land-use productivity. New science and technology must lead the way."