Australia's chief Antarctic scientist says claims by climate experts about environmental changes in the southern continent are not alarmist.

The Australian Antarctic Division (AAD) told a Senate estimates hearing today "rapid changes" taking place across the icy land mass would have significant impact on global climate.

The Mertz Glacier tongue breaks off in the Australian Antarctic Territory. Credit:Neal Young

Changes in ocean flows and shifts in Antarctic ice cap levels were occurring at rates faster than at any other time in history, chief scientist Nick Gales said.

"That's the part that is the most dramatic about the information we're receiving," he told the hearing.