While the development economics paradigm known as sustainable development has been with us for merely a generation or so, the adjective sustainable goes back to 1611, according to OED.  A derivative of that adjective, the noun sustainability, came into use much more recently, which may explain the name attached to the paradigm:

1980    Jrnl. Royal Soc. Arts July 495/2   Sustainability in the management of both individual wild species and ecosystems is critical to human welfare.

We cannot help but agree with the application in that reference.