Apparently PVC creates a lot of its own concerns. I would imagine that the amount needed to cover a glacier would be enormous.
What follows is a quote from a long article on PVC:
So what does all this mean? Is the PVC phase-out called for by Greenpeace justified? What would be the economic implications of such a phase-out?
At this point, we are left with more questions than answers. Greenpeace and the International Joint Commission on the Great Lakes have responded to significant environmental problems resulting from a class of industrial compounds with a call for their elimination. There is merit to addressing the problem of chlorine-related pollution and health problems in a broad manner as they are doing. One cannot ignore the million-plus pounds of vinyl chloride gas or the million-plus pounds of the plasticizer DOP emitted into the atmosphere each year. Or the 15% of cadmium emissions from municipal solid waste incineration that comes from PVC products. Or the evidence (controversial though it may be) linking PVC production and disposal to dioxin, PCB, and furan emissions.
http://www.buildinggreen.com/features/pvc/pvc.cfm