The polar icecap exerts a modulating effect on heat waves. When it melts, long before rising sea levels will kill many, most of humanity will die from the heat wave destruction of the biomass and foodchain. Predicted major die off of 90% of humanity: 2015.
The ice cap is like ice cubes in your summer lemonade. When the cubes melt, your cold drink quickly becomes room temperature. The modulating effect of the polar ice cap in preventing and reducing crop-destroying heat waves will be gone with near instantaneous, non-ending global heatwaves. Everything is usually bigger in Texas, but the that state's Texas-size drought with fires is nothing compared to pending pandemic continental conflagrations that will make the Australian Christmas fire (2500 kilometers long) look like kids playing with matches.
Also see
www.timism.com\GlobalDying\RecordsNew\Polar\PolarTimeBomb.htm
www.timism.com\GlobalDying\RecordsNew\Polar\PolarImpact.htm