Is the world becoming more optimistic or more pessimistic..?

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Someone recently told me that they think the world is becoming more optimistic, and that people are taking things more lightly, but after thinking about it for a while, and asking another friend, I feel that people are actually becoming more pessimistic! I can't think though why I feel that! Maybe I just see more sad faces on the streets than happy ones... news is always about terrorism/global warming/energy crisis/the horrible things that the future has to offer... and when I talk with people they rarely have dreams or hopes and aspirations! And there's so much to dream about! So I was wondering what other people make of this, and if they have any experiences to back it up with! Do you think you are pessimistic or optimistic..? Is it situationally dependant?