The real question is, if sea levels rose due to melting glacial ice, what percentage of the word’s population would get their feet wet? There are several problems with addressing this question, including the fact that it depends on how high sea levels rose. Most studies or calculations are based on what most people consider to be a large rise in sea level of about 10 meters/30 feet. Given this sort of consideration, the number of people living in the global food zone is significant. Here are a few tidbits from the Intertubes:
- Three-quarters of the world’s mega-cities are by the sea.*
- By 2010, 80 per cent of people will live within 60 miles of the coast.*
- …by 2010 some 80 percent of people will live within 62 miles of the coast, with about 40 percent living within 37 miles of a coastline.*
- “For a while, it was said, ‘Oh, two-thirds of all the population lives within 100 kilometers of a coastline,” … The numbers showed that low-elevation areas (under 10 meters/30 feet) are home to 634 million people….”Roughly one in 10 persons in the world lives in this low-elevation coastal zone,” Balk says.*
Current estimates for the absolute maximum sea level rise, if the glaciers at both polls melted, range from 225 to 365 feet, with the latter being more likely accurate. If sea levels rose that much, coastal lands would be depressed several meters and transgressive erosion would also occur. So, for instance, even though Long Island has many points that are above 300 feet or so, none of it would survive the transgressive erosion because it is all glacial till. It is hard to extrapolate from the numbers above to a 100+ meter rise, and improper to do so, but consider that if the human population is concentrated near the seas, and 10% live below the 10 meter line, then it is probably true that well more than half live below the 100 meter line, and many more within the area that would be claimed by the sea through erosion and depression.
I’ve only done a cursory check for sources. If you have better information, please send it my way and I’ll update the post.