What do you think will cause the end of humanity or possibly all life?

Question:

What do you think will cause the end of humanity or possibly all life?

Best Answer - Chosen by Asker:

Global warming. The glaciers will melt and destroy all arctic life and drown many coastal areas ever so slowly. And while half the earth's hemisphere is drowning, the other half will be baking in temperatures that won't allow anything to grow. Eventually all life form will be destroyed. But, once all life is destroyed, the shield on our planet caused by global warming (which is caused by us, of course) will start to deplete and temperatures will return to liveable and life will start again. Nature will always find a way. Life form may be temporarily destroyed, but it will come back.