As the tally of losses from the BP oil disaster keeps running – and as the related lawsuits and insurance claims continue to mount – one group has released a unique new study that seeks to fix a monetary value to the entire ecosystem of coastal Louisiana now under such dire threat.

The Washington, D.C.-based Environmental Defense Fund produced the study, which analyzes the Mississippi River delta as a capital asset and pegs its worth at as much as $1.3 trillion.

Called “Gaining Ground — Wetlands, Hurricanes and the Economy: The Value of Restoring the Mississippi River Delta,” the study takes a comprehensive look at this enormously productive but fragile and badly damaged coastal area. By protecting against hurricanes, maintaining a water supply, supporting fisheries and other food and fur stocks, creating critical habitat and providing waste treatment the natural systems of the delta provide $12 billion to $47 billion in benefits every year. However, the group also points out that much of it is under direct and worsening threat from land loss.

“These huge numbers show that the BP oil spill, hurricanes and continued wetland degradation threaten not only the Gulf regional economy, but the national economy,” says David Batker, an ecological economist and executive director of Earth Economics. “Unlike the Exxon Valdez oil disaster in 1989, we now have solid economics to put a value on the damage done to natural systems and the resulting harm to people. The Gulf economy needs nature to survive.”

The solution advocated in the study is to use the energy, water and sediment of the Mississippi River to rebuild the delta’s wetlands, and the study’s authors argue that this work is a good financial investment for the nation. For example, for every 2.5 miles of wetlands, one foot of a hurricane storm surge is mitigated. The Environmental Defense Funds calculates that if coastal Louisiana still had the 7,000 square miles of wetlands that has been lost here since 1930, much of enormously expensive damages from Hurricane Katrina might have been avoided in the state.

“Large diversions work, so the solution is clear,” says Dr. John Day, a wetlands expert and co-author of the study. “It is rebuilding the Mississippi River delta and that provides hurricane buffering, fisheries, recreation, clean water, and a host of other highly valuable natural system goods and services.

“If healthy,” he says, “the Mississippi River Delta wetlands will provide benefits in perpetuity.”