It's a clich to say that something expensive "costs the Earth." But what is our planet really worth?
At least an average of $33 trillion annually - which is 1.8 times the world's gross national product.
That's the value a team of economic ecologists put on the beneficial goods and services provided by the world's natural ecosystems, not including non-renewables such as fossil fuels or minerals.
Robert Costanza of the University of Maryland at Solomons and his teammates called their estimate low.
"The real value is almost certainly much larger," they say in a recent report in the journal Nature. Nevertheless, they add, "What this study makes abundantly clear is that ecosystem services provide an important portion of the total contribution [of economic activity] to human welfare on this planet."
We couldn't live without those non-human economic services. And if we lost them, we couldn't replace them. There's no practical way that human economic activity could make up for the natural recycling of nutrients such as nitrogen and phosphorous that wash into the sea and eventually return to the land through natural processes.
That service alone accounts for $17 trillion of the team's $33 trillion estimate. The same is true for the natural services that sustain a breathable atmosphere, maintain a healthy ocean with its fisheries and recreational benefits, or continually supply usable fresh water.
Hence the team's conclusion that we should place a much higher economic value on these natural services than we have up to now as we continue to "develop" the planet.
In putting a dollar value on that which has no market price, the team has ventured into economic terrain where most conventional economists decline to tread. To do it, 13 of the new breed of ecological economists from three countries worked together for a week at the new National Center for Ecological Analysis and Synthesis at the University of California in Santa Barbara.
Using all the relevant information they could find in published literature plus a few original calculations, they worked up dollar figures for intangibles such as the cultural value of the world's oceans.
Cultural value includes such factors as recreational use of the sea and the enhanced value of seaside real estate. Or consider the value of forest services beyond supplying timber. Forests stabilize land and regulate runoff. They absorb carbon dioxide. They may enhance surrounding real estate. After all, homes near a beautiful forest could lose value if the forest were clear cut.
Then there are unpriced hidden values. The role of wetlands in processing waste water has no market price. Yet they can sometimes save communities the cost of putting in a third stage of sewage treatment to meet new environmental standards.
What about the value of wetlands in the Upper Mississippi Basin that were filled in to make farmland? Land-use planner Daniel Schneider at the University of Illinois in Urbana-Champaign says draining wetlands along the Illinois River has devastated the river's fish and waterfowl populations. By forcing a need for levees, it also raised flood levels.
He notes that an obvious way to restrict flood damage in that region would be to restore those wetlands to their natural flood control functions. The value of flood damage averted and of recreational uses regained is just as valid an economic quantity as is the value of crops produced on the "reclaimed" farmland.
By putting a dollar value on nature's services, the Santa Barbara team has given planners a tool to aid in future development decisions.
Planners may find that the promised economic benefit of development is more than offset by the loss of even more valuable natural services.