It is very possible that this would make it worse than anticipated, but a quick reminder to anyone afraid ice melting will create a positive feedback loop:
The main thing that takes CO2 out of the atmosphere is the ocean. Adding more water will mean more CO2 can dissolve. This is the main reason why in the past, the climate always returned from getting too hot or too cold.
About 2.5% of the planet's water is freshwater; about 99% of that freshwater is ice, so considering only freshwater ice, if it all melts we'd have about 2.5% more CO2 capacity. There's also such a thing as seawater ice (see: North pole), but it doesn't add that much volume to the system, overall.
Any expansion in CO2 capacity due to melting ice will be completely dwarfed by other effects.
Only the first half of this page is devoted to stating facts; the latter half is a call for political action. The facts section states that the millions of tons of methane trapped in the Arctic ice are a factor not commonly taken into account in future climate models, and its release will very quickly worsen global warming to the point of posing a serious existential risk.
http://www.alternet.org/environment/giant-methane-monster-lurking?paging=off