Today urban areas — ranging from Times Square to a small town in India — cover perhaps 3 to 5% of global land. But Seto and her co-authors calculate that between now and 2030, urban areas will expand by more than 463,000 sq. mi. (1.2 million sq. km). That’s equal to 20,000 U.S. football fields being paved over every day for the first few decades of this century. By then, a little less than 10% of the planet’s land cover could be urban. “There’s going to be a huge impact on biodiversity hotspots and on carbon emissions in those urban areas,” says Seto.
The bulk of that great urban expansion will be in Asia — where more than 75% of the increase in urban cover is projected to occur — and in Africa, where urban land cover will be 590% above the 2000 level of 16,000 sq. mi.