Dr Fraser said carbon dioxide grew by two parts per million (0.54 per cent) in 2005, the fourth year in a row of above-average growth.
"To have four years in a row of above-average carbon dioxide growth is unprecedented," Dr Fraser said in a statement.
"In addition, the trend over recent years suggests the growth rate is accelerating."
He said the 30-year record of air collected at the Cape Grim observation station showed growth rates of just over one part per million in the early 1980s but, in recent years, carbon dioxide had increased at almost twice this rate.
"This is a clear signal that fossil fuels are having an impact on greenhouse gas concentrations in a way we haven't seen in the past," Dr Fraser said.
The good news is that methane has seen a slight decrease over the past two years, and that ozone depleting gases have been decreasing since 1997. Actually, that last bit is fantastic news; it comprehensively demonstrates that we can do something effective about climate threat without suffering a fall in economic growth.
other blogs on: global warming, climate change, carbon dioxide