Glaciers have been melting before and ever since the end of the Little Ice Age.
Glaciers around the world expanded until about 1850, the end of the Little Ice Age. And many glaciers have been on retreat ever since, in most of the world. There are some glaciers that are growing. Yet most are receding. This has happened in the past because of the cyclical warming and cooling of our planet.
Some glaciers didn’t get the memo and started receding prior to 1850.