Probably the most visible example of unintended consequences, is what happens every time humans try to change the natural ecology of a place.

Without reflection, we go blindly on our way, creating more unintended consequences, and failing to achieve anything useful.

Politics is tricky; it cuts both ways. Every time you make a choice, it has unintended consequences.

For the U.S., as the largest player in the global environment, unintended consequences are magnified.

Oh, the unintended consequences of perfidy!

from The Ninja and The Diplomat (coming in September 2015)--As an unintended but ineluctable consequence of the one child policy, he and his wife, like most of his generation and those succeeding, consisted of only children; hence his family included no aunts or uncles, no cousins, and no nieces or nephews. The Chinese family had lost an immeasurable dimension of richness.