How Much "Earth" is Left?

Ever wonder roughly how much of our world is covered in buildings? I found this interesting graph buried in a document about concrete recycling. Isn't it interesting that China, with a population FOUR TIMES larger than the U.S., had a building footprint only 30 percent larger than than ours. Imagine if the Chinese try to adopt Western lifestyle patterns. The resource consumption will literally go off the chart.--M. Power