The word "that" cannot be omitted. I don't know about the original sentence, but an alternate wording could be "that is more apparent here than anywhere".

I'll give you an example: "Hi, I'm Dan, reporting from Beverly Hills, California. Everyone knows that the recession hasn't hurt all Americans equally. Nowhere is that more apparent than here." What is the meaning of "that"? "Nowhere is (the fact that the recession hasn't hurt all Americans equally) more apparent than here." However, the sentence is still confusing. It is very formal, and uncommon in conversation. If we change the order, the meaning is clearer: "(The fact that the recession hasn't hurt all Americans equally) is more apparent here than it is anywhere else in the world." Basically, Beverly Hills demonstrates the fact better than any other place on Earth. "That" must be a fact that you already mentioned.

Nowhere is that more apparent than here. =That is nowhere more apparent than here. =That is more apparent here than anywhere. Am I right?

mucho appreciated :)

Just to clear up... "that" is a pronoun in the sentence. For example, "Life in the desert is harsh. Nowhere is that (ie. a harsh existence) more apparent than here (probably, in the middle of the desert)." Or, "Corruption often interferes with the political process; nowhere is that (ie. the corruption) more apparent than here." In the second example, this might be talking about bribery to gain votes.