3. Thomas Malthus predicted that human population would grow exponentially, outstripping the ability of the world to feed itself and resulting in major famines. Was Malthus right or wrong? Why? What do you think the Earth s carrying capacity is for Homo sapiens, and why?
5. List at least three ecosystem services from which you have bene? tted today. Do you think it is currently technically possible for humans to build infrastructure that can substitute for these services? Would the monetary cost be likely to be reasonable or prohibitive?
1. Is climate change the major environmental health challenge of the twenty- ?rst century? Explain the reasoning underlying your answer.