2021 will start a new decade. :)
3. This debate will occur again in 2030.
Correct, because there was no year zero.
Thank you. Yes 2021 is the new decade
The Roman calendar before Julius Caesar mucked it up by demanding his own personal month, had only ten, 36 day months. When Julius got his month stuck in, they had to change everything to account for eleven months. Thats what it was when Christ was born. . . but then Caesar Augustus comes along and says "I want a month, too!" and pitches a fit until the Roman Senate knuckles under and carves the calendar into twelve 30 day months by sticking August in. . . That happened when Jesus was (maybe?) eight years old in 8 A.D., further confusing time keepers. They stuck those two new months arbitrarily in the summer. Pushing the other months up. Thats why our ninth month, September, in Latin literally means Seventh month, our tenth month October means eighth month, and November, ninth, and December, twelfth. That must have been really confusing for the average Roman citizens. Typical bureaucratic SNAFU. Oh, and then they toss in a six-day holiday after December called Saturnalia, to account for the 366 day length of the year. Us Christians kinda borrowed it, filed the serial numbers off, and just stuck Christmas in there.
But, every years trip around the sun takes ~365 ¼ days, not 366 days and the 366 day Julian calendar slipped out of synch 0.75 day every year or so for years. . . and of course it wasnt reset to reflect year 1 A.D. until Emperor Constantine made Christianity the official religion of the Roman Empire in ~325 A.D.
Then, of course there was the change from that messed up Julian Calendar to the Gregorian in 1582 when October 5th was necessarily changed to October 15th for all Catholic Nations to re-regularize the calendar with the solstices.. . and more importantly for Catholics to calculate Easters date correctly! It was later found that those ten days taken out were not nearly enough. It actually was more like 83 more that needed to be removed to get everything back in sync!
Following that, various nations decided that April 1 was a stupid time for a new year to start, and starting in 1599, moved it to January 1. Great Britain, and its colonies, including the thirteen American Colonies made the change in 1752, which meant 1751 had only 282 days in it. The last nation to change to Gregorian and January 1 new year was Saudi Arabia in 2016. People who insisted on still celebrating New Years on April 1st were ridiculed as "April Fools," stupid people who werent willing to "move with the times."
So, the bottom line is, we really havent the foggiest idea when in time we are!" The best we can do is pick one, agree on it, shake hands, and set our calendars on our smart phones and not worry about it!