Land use is arguably at the centre of any climate change, CSR, population, environmental, trade, poverty (etc) debate. I don't know the answer to this question but hope it will stimulate some debate and provide some answers.
So: if you could only choose one, which of the following would you cut out of your life all together, and why?
If you need a few pointers, this article may help:
Causes of Hunger are related to Poverty - Global Issues