However, it is not simply the aggregate stock of capital in the economy that may matter
but also its composition, in particular whether present generations are "using up" one form of
capital to meet the needs of today. For example, much of the recent interest in sustainable
development has risen out of concern that current economic development may be leading to
rapid accumulation of physical and human capital, but at the expense of excessive depletion and
degradation of natural capital. The major concern has been that, by depleting the world's stock
of natural wealth irreversibly, the development path chosen today will have detrimental
implications for the well-being of future generations. In other words, according to this view,
current economic development is essentially unsustainable.