What is the source of the idea that the Mayan calendar indicates the end of the world on 21 Dec 2012?

I searched Google books, and found no mention of this idea anywhere, until one New Age author, Jose Arguelles, made the claim in two different books in the 1970s and 1980s. He originated this idea that the end of the Mayan calendar indicates a cataclysmic event. (He died in March of 2011, so he did not live to see the day.) Arguelles was not a scientist, nor an historian; he was a New Age author and an artist. The source of this claim is not any of the researchers or scientists who study Mayan culture, and the idea finds no support among them.

The claim that one of the Mayan calendar long cycles ends on 21 Dec 2012 is based on a certain correlation between the Mayan calendar system and the modern (Gregorian) calendar system. But not all researchers agree on when each long cycle begins and ends in the Mayan calendar. And the end of that particular cycle of about 394 years is one of many different cycles in that calendar system. It is in no way remarkable. It is not the “end of the Mayan calendar”, as is popularly claimed. Instead, it is similar to a turn of the century, or of the millennium, in the modern calendar.

At first, Arguelles’ idea went unnoticed by the general public. It spread slowly among adherents of New Age philosophy. The idea came to the attention of a wider audience as the year 2000 approached, and people began to talk more about the end of the world and the Christian concept of the Apocalypse. Only then did Arguelles’ idea become transformed into “the Mayan Apocalypse”.

As someone who has been studying and writings Catholic Christian eschatology for many years, I can tell you that there is no support whatsoever for any type of eschatological event or cataclysmic event on 21 Dec 2012. That date is merely the winter solstice. Many different ancient calendar systems take note of celestial events, such as an equinox or a solstice, as well as the lunar and solar cycles. The use of such ordinary celestial events in a calendar system in no way indicates that a cataclysmic event will also occur.

NASA debunks the 2012 Mayan apocalypse here:
Beyond 2012: Why the World Won’t End

by
Ronald L. Conte Jr.
Roman Catholic theologian and
translator of the Catholic Public Domain Version of the Bible.