Are there any estimates as to how much land would actually end up under water in such a situation?
Would there be a net loss of land above water? Or is there a possibility that land uncovered by the melting ice caps would make up for it?
I’m sure that there are lots and lots of estimates out there, which I’m sure someone will provide shortly. I’ll just point out that simply counting the number of acres exposed vs flooded doesn’t really tell the story. We’re talking about inundating lots of heavily populated, very fertile, useful land around the globe, and exposing barren land that is still in the Antarctic (plus a bit in the Arctic). Global warming is simply never going to make that land as useful as the land we’d lose to flooding.
The bedrock under the Greenland and Antarctic ice sheets is all pretty much at or below (sometimes significantly below) sea level. That’s largely because the weight of the ice is pressing the crust down, and so it might rebound eventually, but probably not over human timescales.
The water would rise 67 meters (that includes Greenland). To see the effect (well, up to 60 meters): Lowest Land Points Below Sea Level Map | Depression Elevations
Of course, right now the average temp in Antarctica is way below 0C, so there is no danger of all of the ice there melting.
I bet half the people in the world live less than 100m above current sea level.
It wouldn’t be the first time that the polar ice has melted. Once was during an extinction event, and the theory that I’ve read is that the area around the equator just got too hot to support life (at least the type of life that had evolved there). If you return to that scenario, all of that extra heat will allow a lot more water vapor to remain in the air. The sea levels will still rise, but not quite as much as what you’d get if you just melt all the existing water and calculate it out from there.
The other condition I read about was a world that was very different than the one we live in now. The polar ice had melted and there were green trees and plants growing at the poles, but the equatorial region wasn’t the hot death scenario as above. Instead, the temperature gradient between the equator and poles was significantly less harsh. Basically, if you had those conditions today, the area around New York City would have roughly the same temperature as Miami, Florida. There wouldn’t be much incentive for “snow birds” to travel to Florida in the winter.
Both of these scenarios are very drastically different from what we have now. Once you start talking about usable land and entire cities that would have to be relocated, you can’t just think only about the rising waters. In order for the poles to melt we probably have to end up in very drastically different conditions that what we have now, and that means a lot more than moving people away from the coast. In some scenarios, most of the southern U.S. could become uninhabitable. In other scenarios, you’re talking about relocating people to the lush forests of Arizona and New Mexico.
The average temperature isn’t the relevant measure. If it’s +5 in some regions (or at some times), and -10 in others, the average is below freezing, but the warm spots are still going to melt. And if you then get a warm spot somewhere else, that’ll melt, too. The melted spots will eventually re-ice if the temperatures go back below freezing, but that can take a very long time (basically, you’re waiting for precipitation, in the driest desert on Earth).
The average high-for-the-day temperature in Antarctica, during the warmest month (December) is -16F. There is no danger of things melting.
Once in a while, the northernmost part of Antarctica (the warmest) may get to as high as 41F for a couple of hours. But rarely.
I am more concerned about the loss of the ‘third’ ice cap, and I do not mean the Greenland ice sheet.
The ice on the Tibetan plateau feeds several major rivers that supply water and life to some of the most heavily populated, and poorest, areas of the world. The Ganges, Mekong, Yellow, Yangtse, Indus, and other rivers, all rely upon the ice on the plateau.
Sea level rise will displace many people but the potential loss of water supply from the Tibetan mountains will result in a real disaster. You do not see this talked about much.
Look at this map and think about these rivers no longer supplying reliable water to the land below. From a humanitarian viewpoint this is a much scarier possibility than people having to move away from coastal areas or major cities needing to raise their levees. These people have no where to go, and little money to address the issue.
Well you have a northern sea route and new land in the South. I can see, China, India, Australia even South Africa, Argentina and Pakistan all vying to get a foothold there.
Awesome, if the oceans rise by 60 meters, I’ll be within three blocks of the bay. Then again, we’ll lose the entire San Joaquin Valley and all of its farmland, and we won’t have a way to get fresh water to the Bay Area… and, it looks kind of bad for Florida and The Netherlands.
Why would the ice melting cause the rivers to dry up? You’d need some combination of lowered precipitation, or more ice forming, to reduce the total river water. If the average amount of ice over a year were held fixed, then the river water would all come from precipitation, not directly from the ice.
Let’s not forget that hotter water expands, and the oceans are on average about 2000 feet in depth. Heat up the oceans on average and the water already there expands to make sea levels even higher than just ice on land melting.
I think the issue is an increase in seasonal variability. Without the glaciers feeding the rivers during the dry season droughts will be more severe, and if precipitation stays the same during the wet season, but some of it changes from snow to rain I suppose floods would be too.
The ice in the North Polar sea is already in the water, it melting will contribute nothing to sea levels. All that matters is the Antarctic and Greenland ice.
If any of the ice gets to above 0c that part will melt regardless of the average temperature. Vast areas of the Antarctic ice sits on land that is underwater, held down by that ice. Its feet are being warmed and so melted by the warming Southern Ocean and the consequently reduced ice mass there allows the glaciers to flow faster into the ocean, putting more ice into the danger zone. Averages are not useful here.
Hey - I’d be within 200 yards of the beach, instead of 50 miles. Cool.
I’d be underwater. Less cool.