Complex sentence: It has a unique mandate--to use the power of photography to communicate crucial messages to a global audience; and it has as its goal art of the highest order, applied to the immense social and environmental threats of the new millennium.
Split into simpler sentences: It has a unique mandate--to use the power of photography to communicate vital messages to a global audience. The goal is to uncover art of the highest order, applied to confront the pressing social and environmental challenges of the new millennium.