wilderness

As the debate about how to revive our economy while sustaining our environment heats up, it's important to remember that the economic driver truly "too big to fail" is Mother Nature herself.

It's been calculated that nature's "Ecosystem Services" are worth over $33 trillion dollars a year – nearly double the size of the global economy. And while that figure is important for putting a value on Nature's contributions to the economy, it belies the fact that without nature we could not survive at all.

So the true value of natural services? Priceless.

In their seminal work "Sustaining Life: How Human Health Depends on BioDiversity," Harvard M.D.'s teamed up with Oxford University Press, the U.N. Environment Program, and famed biologist E.O. Wilson to compile a comprehensive picture of how diverse species and ecosystems provide "materials, conditions, and processes that sustain all life on this planet, including human life."

Here's a look at the Top 10 things Mother Nature does for us for free, year after year, that we couldn't even begin to do ourselves without her: