No, "on record" means a year that we have recorded. The year 700 BCE is not "on record", but 1970 CE is.
While the author of the comment was trying to imply that it could get worse, actually they are correct in the other direction. Meaning that if the weather turns cooler (like from a volcanic eruption which releases a lot of particles into the upper atmosphere), then it will no longer be the hottest year.