I promise you, it's a lot worse than you think. If you're worried about sea-level rise because of global warming, you're only scraping the surface of what horrors are imaginable, even in a teenager's lifetime today. Despite this, the rising seas — and the cities they would drown — have dominated the picture of global warming and swamped our capacity for climate terror, obscuring our understanding of other risks, many of which are far closer at hand. Rising oceans are terrible, extremely bad; nonetheless, evacuating the shore will not suffice.
Indeed, unless billions of humans make big changes to how they live, sections of the Earth will likely become uninhabitable by the end of this century, and other regions will become horribly inhospitable.