Sea level rise
Rising sea levels across the globe pose major concerns for the majority of the population in coastal areas. According to the US Environmental Protection Agency, sea levels have risen by 7 inches over the last century. However, the annual rate of rise over the past 20 years has been 0.13 inches a year, roughly twice the average speed of the preceding 80 years. Accordingly, mean sea levels are projected to rise even further in the foreseeable future. The continuing melting of glaciers and the thermal expansion of water are projected to raise mean sea water levels between 3 to 7 feet by 2100. Models of worst case scenarios project oceans to rise by nearly 25 ft. For perspective, a sea level rise of 25 feet would completely submerge the cities of Los Angeles and London.
a look into Indonesia
The country of Indonesia has a vast coastline, roughly 81,000 km. Population densities along the country's coast average between 500 and 2000 people per square kilometer. However, population densities can be as high as 35,000 people per square kilometer. Also, coastal erosion has increased significantly and with a potential 1 meter sea level rise, it can be estimated that around 405,000 hectares or 1,000,000 acres of coastal land including small islands will be flooded. With simple math, this puts between 2 to 8 million people at risk at being underwater and possibly losing their homes.
Statistics from the Philippines
Statistical figures above taken from http://www.preventionweb.net/english/countries/?cid=135