America's corn stocks are at their lowest in 20 years due to one of the hottest July's on record. The impact could affect ethanol production which is created using corn harvest in the US. Which could in turn mean an increase in CO2 emissions as well as a further increase in droughts from climate change. But the United Nations has urged that the US government to stop using corn to make ethanol to avoid the possibility of a food crisis. In an election year it is unlikely that President Obama will give in to pressure and take any political risks. Al Jazeera's Kimberly Halkett reports.