It exists, it will be bad for coastlines, it won't be an Armageddonist event.
Unfortunately, melting glaciers won't "just" make ocean level higher, sinking many coastal areas and islands.
First off, such a massive influx of water would deprive oceans from a lot of oxygen, leading to catastrophic consequences. Second, glaciers are important source of fresh water, with desalinization technology being too complex and expensive for the mass use (not to mention it produces a lot of pollution). Third, a possible apocalyptic scenario is possible, if melting glaciers frees unknown viruses or germs we have no immunity against.