Tuesday, March 20, 2007

Flood Maps

Flood Maps, by Alex Tingle, show the effects of sea level rise of up to 14 meters in Google Maps. You can set the sea level rise for the best estimate you have. My neighborhood is still above water, but Chiba has become an island, with perhaps a bridge or tenuous causeway to the rest of Honshu, and most of the east side of Tokyo is underwater. I understand the White House will be waterfront property in the 14 m scenario. If the entire mass of the polar ice caps melts, sea level rises could be much more than this, but that may occur over several centuries. The old city of Funabashi will go underwater and Higashi Funabashi will be a beach area. Water comes up on several sides of Tsudanuma station.

Update 2007-03-20:
I should mention that a complete polar meltdown to ice-free status would raise sea level by around 80 meters, 73 meters contributed by Antarctica and 6 meters contributed by the already-melting-and-likely-to-accelerate Greenland, according to the USGS. Historically ( in geological history), this is not unusual. I also like to point out that sea level was 130 meters lower in the last ice age, 18,000 years ago, and only neared the present levels 8,000 years ago, not so much earlier than the construction dates of early pyramids 4600 years ago. Thus a rise or fall in sea levels of tens or hundreds of meters should not be beyond our imaginations, but the poverty of imagination is one of the great resource scarcities of this time.
The inside of the Yamonote Line would still be above water after a sea level rise of 14 m. One could conceivably board a speedboat shuttle near Tsudanuma or Higashi-Funabashi to commute to a disembarkation point somewhere between the Akihabara and Ginza waterfronts. Tokyo Bay submerges "shitamachi" areas and extends far beyond Saitama City, halfway to Maebashi, Gunma.

NASA and Google should be credited for the data which Alex Tingle so elegantly programs and displays.

In order to view sea level rises above 14 meters as well as negative numbers, try http://kirk.caset.buffalo.edu/~depape/topo/

or try running the Java applets of Sebastien Merkel at http://merkel.zoneo.net/Topo/Applet/
I have trouble understanding some of Merkel's figures: How could sea level have been 300 meters higher 95 million years ago and 600 meters higher 450,000,000 years ago -- unless the earth is losing water to space?

Check out Japan without the Kanto Plain, just the Kanto fishing grounds. Part of the Boso peninsula has survived as an island. This is an 80-meter sea-level rise, the result of ice-free polar regions. (By the way, I tweaked the gamma, contrast, and saturation to make the screen shot of the Java applet more vivid.)

One final alternative for similar explorations: The University of Arizona.


Eli said...

Just a note about distant past sea level findings...one reason that sea levels would have fallen since prehistoric times is the general expansion of the earth itself since those times due to plate tectonics and the accumulation of debris from space.

Blues Tea-Cha said...

It occurred to me later that water on the Earth is not a fixed quantity. It is breaking into hydrogen and oxygen all the time through photosynthesis and other chemical and biological processes, so all of the oxides and hydrates, hydrocarbons, and so on could reduce the quantity of water on the Earth's surface. There could also be lots of water in the earth's crust as groundwater, which when depleted, causes the surface to be below sea level in many cases. It still seems hard to account for a 600 meter deep, planetwide sphere of missing matter.

I'll have to accept your plate tectonics (and piled up space debris? Really?) as the best explanation offered up so far.