Does The New Decade Begin Next Year?

Now that we're comfortable inside the New Year, there is controversy as to whether or not we have started a new decade.  Social media is a buzz as to when the new decade actually begins: January 1, 2020 or January 1, 2021. Most people agree that decades begin on years ending with zero and end on years ending with nine. The '70s ran from 1970 to 1979, the '80s went from 1980 to 1989, and so on. But a swell of people says that way of thinking is incorrect. Because there was no year 0, they argue, it's more accurate to say that decades begin on years ending with one and end on years ending with zero. That argument is based on the Gregorian calendar, which is oriented around the birth of Jesus Christ. In the 6th century, an abbot named Dionysius Exiguus attempted to calculate the year Jesus was born. Dionysius labeled the year of Jesus's birth with the Roman numeral for one (I) since the concept of a zero didn't reach Europe until at least the 12th century. So technically, it's only been 2019 years since the year Dionysius determined was 1 A.D.—not 2020. That's led some organizations, like the Farmers' Almanac and the United States Naval Observatory, to favor a decade that begins in 2021 and ends in 2030. Alas, which ever camp you choose to believe, you would be correct.  Quite simply, a decade is a 10-year period. So 2020 to 2029 works just as well as 2021 to 2030.