Of course its only a tiny portion of the polar cap, what do you expect? The whole thing to melt all at once? That much ice at any temperature would take a long time to melt, and much of Antarctica is still more than cold enough to be frozen.
We know that glaciers are melting, and we know the sea level is rising slowly, and the climate has gotten slightly warmer and atmospheric carbon dioxide levels are rising. We also know that internal combustion, deforestation, and other processes produce greenhouse gases, and that these have been going on for over a hundred years, during which time, all these other things have occured. It seems reasonable to me to take precautions to ensure that we are not damaging the Earth's climate in ways that may negatively influence us.
I admit that I don't know everything and no one does. But when a large amount of evidence accumulates, pointing to climate change, it is worth looking into.