Because most glaciers are receding and only a few exceptions (like the Mount St. Helens special crater-shadow case) are advancing.
Of course the glaciers are SUPPOSED to melt in a temperate time, if they didn’t Canada and most of the northern US would still be under miles of ice. The whole freaking out over melting glaciers thing just proves that the global warming alarmists don’t really understand how climate works. If you’re not in an Ice Age the glaciers are melting, period, end of sentence.