"Green accounting"

If the value of an asset like a machine is reduced as it wears out, proponents say, the same accounting principle should apply to a dwindling natural resource.

"Environmental arguments come from the heart. But in today's world based on economics it's hard for arguments of the heart to win," said Pavan Sukhdev, a former banker now leading an ongoing project that was proposed by the Group of Eight industrialized nations to study monetary values for the environment.

That study, started in 2007, has estimated the world economy suffers roughly $2.5 trillion to $4 trillion in losses every year due to environmental degradation. That's up to 7 percent of global GDP.

But environmental accounting still faces many detractors and obstacles. Among them is resistance from governments who might lack the resources and expertise to publish a "greened" set of national accounts alongside those measuring economic growth. Particularly in the developing world, many still struggle to produce even traditional statistics that are timely and credible.

Opposition is also expected from parts of the corporate world, since green accounting could make doing business or buying products more expensive.

A forest once valued by what its trees fetch on the timber exchange might instead be valued according to the carbon dioxide it absorbs, the animals it supports, the water it filters and the firewood it provides. Or it could be revalued with future generations in mind. That might lead to higher felling fees, pricey replanting requirements or more expensive wood. Some might rethink the economic benefit of cutting it down. Science would become a more important factor in economic decision-making.