The Amazon rain forest is seen near construction of the Belo Monte dam complex in the Amazon basin near Altamira, Brazil. (Mario Tama/Getty Images)

Centuries before Greece went broke, its citizens would climb to a temple in Delphi and ask questions of a priestess who, perhaps influenced by the “brain-altering vapors” from underground gas deposits, was said to receive messages from the gods.

No word on the air quality at the World Bank, but one recent research puzzle was submitted to another Delphic oracle of sorts to answer the following: How much could you tax European families to save the Amazon rain forest?

Emerging from a long recession and wondering when their children will find jobs, folks in Spain and Italy and perhaps Greece itself would no doubt be happy to write an annual check to the government of Brazil, or to logging companies, or agribusinesses or local tribes, to leave the rain forest alone.

However, researchers Stale Navrud and Jon Strand of the World Bank’s energy and environment team did not have the funds available to conduct an opinion survey of actual Europeans with actual bank accounts.

So they did the next best thing. They turned to a “Delphic panel” of 48 “European environmental valuation experts” who provided their best guesses at what families would pay to have the rain forest preserved in its current state — halting all environmentally degrading uses (and, no, they did not say whether zip lines through the canopy would be barred).

(The Washington Post)

The answer: about 36 bucks a year, though that average covered a range of more than $100 per family in Germany (these guys obviously haven’t followed recent German attitudes about anything involving Greece) to about $4 in Croatia.

Because of the Amazon’s significance — its importance to the global environment and its attraction as a tourist spot — the researchers write, “households worldwide might be willing to pay to reduce or avoid additional losses” from logging, farming and other industrial activities.

It is not clear how that will go over with the tea party in this country, or with Europe’s equivalent, but there is a serious issue lurking behind this calculating. The rain forest is one of the planet’s great oxygen producers and carbon dioxide sinks, and it is important to biodiversity. It is what development economists refer to as a “global public good.” Like any public good, it is hard to protect and manage. The motives for individual profit in the short term are high; the damage to public interests are apparent over a longer time frame.

But if we move to a planetary tax to protect such things, why stop at the Amazon? Indeed, based on this round of Delphic consultation, the authors suggest that the process could be “used more widely as a tool for global benefit transfer” — a way to determine the worth and proper tax for all the world’s public treasures.

Anyone want to bid on a glacier? Or Miley Cyrus?