The biggest ethical issue in our world

I'm teaching a college ethics class right now and recently asked my students (as part of an online discussion forum) this question: What is the biggest ethical issue facing our world? The answers have been insightful and thoughtful and include the economy and corresponding meltdown of the financial markets, to greed, to misunderstanding of different cultures, to stem cell research, to a sense that people overall are apathetic and don't care about these and other issues. So, what say you? What's are the bigger ethical issues facing our world today?