Curious what the planet would look like if all the world’s ice melted? Let’s just say the topic has been on my mind lately. National Geographic did the math, with pictures to help us wrap our heads around it. If all the world’s ice melted—an extreme eventuality that would require thousands of years—sea levels would rise an estimated 216 feet. Unsurprisingly, what we know as “coast” today would become “offshore.” In North America, the Atlantic seaboard is gone, as is Florida. In my novel (set in 2139), the Philly Bay is a thing, but that was based on a model of just 22 meters (72 feet) in sea levels rising. In Nat Geo‘s more extreme model, the Central Valley in California becomes a giant bay. San Diego goes bye, bye, as does a little town in Texas called “Houston.” Nat Geo has detailed maps of all the continents, including the desert formerly known as North Africa, the desert formerly known as Australia, and parts of China that are currently home to some 600 million people. As noted above, this map represents the ultimate extreme of global warming, including melted Antartica ice sheets that have survived previous warming periods. The point, though, is that it’s fascinating to see what it might look like.