Send More Urban Planners

More human beings are moving to cities. You already know that. But according to new data (plus maps!) from the Global Rural Urban Mapping Project at Columbia University (yes, that acronym is GRUMP), the Earth looks even more citified than anyone thought.

Mixing satellite data with stats from that Gridded Population of the World project I blogged about the other day (Jeez, these Columbia U. guys are all over this stuff, huh?), the GRUMP maps are the first-ever attempt to combine population size and the geographical extent of urban areas. Suck on that, United Nations Human Settlements Programme!

Cool results from the number-crunching:

GRUMP shows that 20% of the world's urban settlements have populations below 500,000. This is an important finding considering that the UN Population Division only reports on urban settlements of 500,000 inhabitants or more.

GRUMP data indicate that roughly 3% of the Earth's land surface is occupied by urban areas, an increase of at least 50% over previous estimates that urban areas occupied 1-2% of the Earth's total land area.

Coastal environments have much higher concentrations of urban land area (10%) and urban populations (65%) than other ecosystems. 

Far fewer Asian and African urban residents live in coastal and cultivated areas than residents of the Americas, Europe and Oceania, however, population densities in coastal cities of Asia and Africa are much greater than those on other continents.

GRUMP shows that approximately 7% of the world's population now resides in the largest mega-cities, whereas experts had previously estimated this number to be around 4%.

GRUMP has identified about 75,000 distinct settlements worldwide, but only 24,000 urban areasâ€"the result of many agglomerated urban settlements.

I know I'm harping on this, but superdense, super-poor, massive urban development on equatorial coasts practically begs for more kilodeath-scale tsunamis, quakes, etc (and destroys the environment while we wait).

(Spotted in the March 18 issue of Science, specifically this article [subscription req'd].)