The Worth of the Earth What's the Combined Value of All the Real Estate on Earth?
Steven Cord in 1985 published an article in the American Journal of Economics & Sociology on total U.S. land values. He concluded that the values came to 24 percent of U.S. GNP, and one of his sources was the Federal Reserve. He reports he hasn't done anything since then to update the number. David Morris of the University of Wisconsin has done more recent work at http://morris.marginalq.com/land_sector.html. His estimate, based on flow of funds data from the Federal Reserve Board, indicates that the total value of private U.S. land, including a small fraction owned by nonprofits (and therefore probablky not taxed, or not taxed at a full rate), was $12.4 trillion in 2007. This is a little less than GDP, but doesn't include farmland. With farmland, maybe equal to GDP? The USDA estimates the average value of U.S. farmland at $1,200 an acre. Land is estimate at 79 percent of the assets of farms - see http://www.ers.usda.gov/Briefing/landuse/aglandvaluechapter.htm.
If we add $3 trillion for farms, we have a total value of private land of $13.4 trillion.
We might add $10 trillion more for government-owned property, but any attempt to sell this property would lower the value of other land in the area, so perhaps only $4 trillion of this should be added as usable (sellable for development) land.
That yields a total value of land of $17.4 trillion, which is 178 percent of 2008 U.S. GDP of $14.3 trillion, or 122 percent.
Applying this percentage estimate to world GDP of $60 trillion in 2008 (based on IMF data for individual countries) yields a total Worth of the Earth of $73.2 trillion.