Considering Land Elevations and Sea Level Rise Aside from the conjecture of whether there is global warming or not, or whether man is the principle cause of it or not, one thing is clear: there is a lot of water stored up as ice on the Antarctic continent and on the island of Greenland. If the Earth does indeed warm up enough to melt those masses completely, what kind of effects could we expect to see? Let's get some numbers to play with, even if rather rough. From Wikipedia's article on Antarctica, we are informed that the area of the continent is 14.4Mkm², and that 98% of that is covered by an average of "at least 1.6km" of ice. so 0.98 x 14,000,000km² x 1.6km = 21,952,000 cubic km of ice. Similarly, from Wikipedia's article on Greenland's ice sheet, we are informed that its ice occupies 2,850,000 km³. Adding the ice from both land masses, we get 24,802,000 km³. From Wikipedia's article on "Ocean", we are informed that the area of all the Earth's oceans total 361,000,000 km². Dividing the volume of ice by the surface area of the oceans and converting to meters, we can find out about how much higher the sea would rise to accommodate all the water from the ice caps, should they melt: 24,802,000 km³ / 361,000,000 km² x 1000 m/km = 68.7 meters. Icebergs (made from glaciers) float. That means they're less dense than sea water. So we can't assume the full volume of ice translates into the same volume of water. Icebergs are typically 88% (that's "over 87%") the density of sea water, although other sources say that individual bergs can vary from 55% to 99%. So sea level rise would come to 88% of 68.7 m = 60.5 m, or about 61 m (200 ft). That's disaterous if you live in say, Florida, the Netherlands, Denmark, Bangaladesh, or along any coast that has low geographic relief. I live in the state of Washington (WA), in the northwestern corner of the continental USA. I happen to have the capacity to perform some mapping of elevations and depths, and I wondered how my neighborhood (i.e., coastal WA) would change if sea level actually rose. So I made some maps and am sharing them with you here. Before clicking on the links and getting all depressed or making (hasty) real estate descisions based on these maps, there are some offhand things you should consider: Timing: if global warming is enevitable, it will probably take a "long" time (several generations?) for the oceans to fully rise. My maps show a rise to 69 m, made before I factored in the densities of glacial ice and sea water. This mostly changes the outlook for those in southern Puget Sound and along the Black River. Current thinking in this neck of the woods is that we'll see a 2m rise by between 2050 and 2100. Look for the coastal areas between current sea level and 2m elevation, shown in pink. That's the area we're talking about. The data was based on a 30m (98ft) digital elevation model (DEM), which means the data has a value for height every 30m across the state. This isn't really fine resolution for accurate (down to your street) shore work. There's no consideration for the expansion of sea water due to its warming. It's significant enough that such changes are used in approximating temperature changes from satellite readings of anomalous sea level changes, but I have no idea how to equate it. As sea level increases, so does the surface area of the oceans as they cover up land. This increase in area probably doesn't slow the rate of rise by much though. The melting of other land-based glaciers is not accounted for. It's not only Greenland and Antarctica where ice on land is found. But my brief research tells me that this is a very small (less than 1%) contribution. Cloud cover might suck up some of this water. I suspect that would be an insignificant amount though, and there's no-one I know of saying heavy global cloud cover is an inevitable result of global warming. I removed landward depressions (bowls) forming at the various sea levels. Global dimming is not considered. Mostly, global warming is generally accepted among mainstream science as currently under way. Debate exists regarding its rate, magnitude, and full effect.

So without further ado, here are the PDFs of the elevations in Washington state:
817kB, 150dpi No labeling	837kB, 150dpi With geographic labeling
318kB, 150dpi With geographic labeling.	The map at left highlights some of the most prone areas of coastal WA affected by a 2m rise (in pink). You can get a rough idea of how much of the state is prone by looking at the pink areas in the thumbnails above.

What I've Learned and Pondered

One thing that I've loosely rued is my omission of the landward depressions. These are "bowls" in the topography that are naturally diked by surrounding terrain from the sea as it rises. They'll become bays when sea level reaches their sills. Could landslides increase because of supporting land being relatively (geologic scale) quickly eroded by sea water? These could cause huge local tsunamis. Think in terms of the Lituya Bay, Alaska 500m-high event of July 9, 1958. Coastal roads are going to be a problem. How far inland will new ones be built, and on what time scale? This will also cause large numbers of condemned properties in the name of Eminent Domain. Gravity-dependent sewer systems will fail once sea level reaches them. New systems will have to be built. Those usually evolve with cities, and treatment plants are typically built at the "bottom of the hill". So they'll be first to go. Somebody's going to have to rename a whole bunch of new islands, peninsulas, bays, passages, etc. Paraphrasing Donovan, get out your cosmic crayons kids, and fill them in! The Olympic Peninsula becomes Olympic Island if the sea gets to about 30m. Ulimately, I think there is a socio-economic timing issue if your coastal house is a retirement investment or planned inheritance. That is, if sea level rise becomes accepted fact and you're in the flood zone, no-one will want to buy your house, even if it's years away from becoming a reef. The timing is something you'll have to work out on your own. I guess this means the government is going to bail out homeowners in the flooding areas, like they do for the chuckleheads who insist on building in river flood plains now. Get ready for tax increases!