The Earth is getting hotter. An increase of 3°c will affect hundreds of millions of people. Sea levels will keep rising.
The UN says cities on the coast will be under water in the future. Countries need to reduce their CO² emissions quickly.
3°c more heat could increase sea levels by 2 meters.Cities from Shanghai to Alexandria and Rio to Osaka are in danger. 
Miami will be under water and so will the lower 1/3 of Florida.
The Guardian newspaper says countries are not prepared for this. They are also not prepared to stop it happening.
Scientists say we need to keep temperatures within 1.5°c – 2°c of warming. Change is happening too slowly, the UN says. They say government targets are only 1/3 of what we need.
A 3°c rise will lead to longer droughts, stronger hurricanes and lock in sea level rises. Higher sea levels will change the maps of our coastline. Scientists say 2 meter sea level rise may happen by 2100.
More that 275 million people live dangerous areas. Shanghai, Shenzen, Bangkok and Tokyo will be affected. Japan’s second largest city, Osaka, will lose its business and entertainment areas, Umeda and Namba. They will need to build flood defenses or reduce CO².
Unfortunately, Japanese cities and other countries with less money will not be able to build flood defenses.
https://www.theguardian.com/cities/2017/nov/03/miami-shanghai-3c-warming-cities-underwater