In my opinion the biggest problem facing human in the next 100 years is pollution such as nuclear waste. Atomic power is very good source of energy so humans can save oil. Humans can use water and many other things to make power but there are dangerous threatening things and nuclear waste is one of them because it doesn't natural to the environment. Meanwhile all countries want to discover new knowledge. I think they don't think about what might happen in the next century or in future. This is a serious problem, like what to do with the waste because we are no longer allowed to throw them into ocean or bury it under ground. This waste can cause the earth to be destroyed, so it is impossible to grow anything in that area.
The possible solution is we can use that energy just for some special cases. Politicians should not use this energy for war weapons, Atomic bombs or experiment on humans' body. The devastation caused to Hiroshima and Chernobyl shows that atomic weapon and power can