Global warming forces agriculture to be productive under marginal conditions. However modern maize hybrids fail to meet this requirement. Although breeding has achieved spectacular progress in grain yield, yields at low plant population densities remain almost unchanged. Maize hybrids are indeed unable to take advantage of resource abundance at low populations. Consequently, the optimum population varies greatly across environments. Dr. Ioannis Tokatlidis reviews the consequences of climate change on crop sustainability under widely diverse environments, and proposes crop management strategies to address the situation.