4. Rising sea levels making some cities uninhabitable

Assuming that current rates of climate change continue, it has been conservatively estimated that there are billions worth of assets and millions of people that will be lost and displaced by the end of the century.
Some countries are more affected than others but overall, both developed and developing nations are at serious threat from losing a sizable percentage of their land mass and some of their most economically important and most populated cities.
By percentage of population that could be displaced, the Netherlands is most at risk. By total number of people displaced, China is most exposed and by potential monetary assets lost the USA stands to lose the most.