From the BBC’s “Science and Environment” section yesterday:

The global economy is losing more money from the disappearance of forests than through the current banking crisis, according to an EU-commissioned study.

It puts the annual cost of forest loss at between $2 trillion and $5 trillion.

The figure comes from adding the value of the various services that forests perform, such as providing clean water and absorbing carbon dioxide.

[…]

Key to understanding his conclusions is that as forests decline, nature stops providing services which it used to provide essentially for free.

So the human economy either has to provide them instead, perhaps through building reservoirs, building facilities to sequester carbon dioxide, or farming foods that were once naturally available.

Or we have to do without them.