27% percent higher than last year?
"Levels of CO2 are now 27% percent higher than at any point in the past 650,000 years, according to research into Antarctic ice cores."
Last year is a point in the past 650,000 years.
Are you saying that CO2 levels today are 27% higher than last year?
If not, you are writing in a very sloppy way, which indicates that a scientific, fact-based discussion is not on your mind -- doesn't it?
Now don't whine that 'we know what you meant to say'. SAY IT right the first time.