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I have two global polygon shapefiles in WGS84, and I would like to generate spatial stats on the % area of one shapefile that is overlapping the other. I understand that geometric calculations such as area require a projected coordinate system, but I am wondering if that is necessary in order to calculate % overlap.
I would like to avoid projecting, as these are large datasets. However, in the event that I do have to project, are there recommended projections for running geometric calculations on global data? I've only ever worked with local / regional projections. I am using ArcMap 10.2.