Global Climate Change
I find that global warming is a serious issue, alth0ugh second to the possibility of nuclear war, and that it could potentially destroy our way of life and planet as we know it. Note I did not say destroy Earth because that would be too extreme; there will likely be some organisms or even humans left to rebuild in the rubble. However, if left unchecked, it can and will trigger a disaster. Here's an analysis: if the temperature goes up another few degrees, methane pockets underneath the oceans will be able to burst. Also, large amounts of methane hidden under ice, with the ice gone, will be able to emerge. Here's the point: methane, CH4, is an even stronger greenhouse gas than CO2, somewhere on the scale of ten times stronger. And after that the greenhouse effect will go runaway until the methane decomposes into carbon dioxide. Many skeptics at this point would say, bah, the Earth's temperature hasn't gone up / has barely gone up / is simply undergoing natural...