CSIRO senior research scientist Dr Paul Fraser says the amount of carbon in the atmosphere has reached 390 parts per million.
"We find no evidence going back 800,000 years of CO2 levels above 300 parts per million," he said.
Dr Breganza says the pace of climate change is alarming.
"In the geological history of earth, global changes of this magnitude happen very rarely," he said.
The report says the projected increases in temperature will lead to floods, droughts, and extreme cyclones.
And it says global sea levels continued to rise, with the CSIRO putting them at 210 millimetres higher than they were in 1880.
Dr Braganza hopes the report will convince people the climate is warming and that the pace of change is worrying.
"Global changes of this magnitude happen very rarely. They happen when asteroids strike, they happen when there's planetary volcanic activity," he said.
"They're happening now because we're digging up fossil fuels and basically burning them all. And we're doing that very, very rapidly.
"And that transition system has a lot of unknowns in it, a lot of nasty surprises."