Seriously, there was! Or at least, there COULD have been.
Snooty pretentious people like to sneer at those who would say 2000 is the start of a new millennium, or 2009 is the end of a decade, by saying, "Well, there was no year zero, so the decade/century starts at whatever-01, so blah blah blah".
The idea that there can have been no year zero depends on one counting years the way one would count, say, magic beans, that is, start at 1, then 2, 3, etc.
We are counting years here, and not just years, but years since a supposed person's birth (we are aware that the said birth probably never even happened, and even if it did, it didn't happen at the point the calendar's dated from, but that's the conceit it's based on, so let's go with it).
And what do you do when you count the years since someone's birth? You say "Mr X is ONE, when he has finished his first year, not when he is starting it.
In other words, in all of our lives, there IS a year zero - the year from our birth up to our turning one year old.
And there is no reason not to suppose that, say, the year 2010 marks, not the start of the 2010th year, but the year following the END of the 2010th year.
That is, the number attached to the year indicates the "age" of the world, counting from 0, not the progressive year. In just the same fashion as somebody who is 50 is living in their 51st year, and the 1900s were the 20th century, it is entirely reasonable and consistent to say that 2010 is the 2011th year.
Now of course it's all arbitrary anyway, and the starting point of our calendar was just plucked out of the air, but the fact is that those who claim "there was no Year Zero", "the millennium began in 2001, not 2000", etc., are relying on making a grand statement that sounds unassailably rational, and will therefore not be questioned. Since, once questioned, the grand statement is found to be entirely without evidential backing, and the stater to have not a leg to stand on. The entire argument is a house of cards, waiting for clever people like me to blow on it.
There is absolutely no reason there can't be a year zero. The assertion that there was is just as sensible as the assertion that there wasn't, with the added bonus that it accords with our natural human sensibilities to see a year like 2000 as a milestone, rather than 2001.
Incidentally, the only reason people are really kicking up about 2010 not being the start of a new decade is that 2010 is not blatantly enough a change from 2009, especially since most people are still pronouncing it "Two Thousand and Ten". It's a lot easier emotionally to accept 1990 as a new decade following 1989 - 80s to nineties - than it is the seemingly non-existent distinction between nine and ten.
Tell your friends!