Please, look at the bolded which it is in the following passage. I don't think it is a relative pronoun, but I can't find which used as a conjunction in a number of dictionaries. How is which used in the sentence? I'm sorry I couldn't find the source of this passage.
Whenever our urge is to fight a specific biological change, we should
ask the following triplet of questions. Will our efforts have made
much difference a few hundred years hence? If not, this means we are
fighting a battle we will inevitably lose. Next, will our
great-grandchildren’s great-grandchildren be that bothered if the
state of the world has been altered, given that they will not know
exactly how it is today? If the answer to this second question is no,
this means we are fighting battles we do not need to win. If change is
inevitable, which it is, we should then ask a third question:
how can we maximize the benefits that our descendants derive from the
natural world? In other words, how can we promote changes that might
be favourable to the future human condition, as well as avoid the
losses of species that might be important in unknown ways in future?
Best Answer
I agree with Jason that it is a relative word, not a conjunction. However, relative pronouns usually refer to a preceding noun (except for sentential "which").
In this case, it is at least curious that it refers to an adjective. I don't think the antecedent is "inevitable change", but just "inevitable", the relative clause being more or less equivalent to the far less idiomatic:
Within the relative clause, "which" is the subject complement, and "it" (standing for "change") is the subject of the clause.
Another example without a noun will show my point more clearly:
It is clear that "which" refers to the participle "interested".