I remember a knowledgable acquaintance discussing climate change in depth in a very sobering way - it was the first time I'd heard much about the 'water wars' that would be problematic one day. I was young and immature and talking about 2030 or 2050 seemed ages away.
Realised with a shock that those chats were a decade ago 
and time whirs past at warp speed the older you get!
What will things be like in another ten or twenty years, in terms of food and water supply around the world, do you think?
What will be the first effects seen in a geopolitical sense?