Carbon dioxide levels in the atmosphere are now higher than at any time in the last 800,000 years, while the last decade in Australia was the warmest on record, CSIRO scientists say.

The findings are released in the CSIRO's annual State of the Climate report, which has been released today.

The report says Australia's annual-average daily maximum temperatures have increased by 0.75 degrees Celsius since 1910.

Australian temperatures are forecast to rise by between 1C and 5C by 2070 "when compared with the climate of recent decades."

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But CSIRO says 2010 and 2011 were the coolest years recorded since 2001, because of two consecutive La Nina events.

Dr Karl Breganza from the Bureau of Meteorology says that while 2010 and 2011 were slightly cooler due to high rainfall, temperatures are still increasing.

"Australia tends to be cooler during periods where you have intense rainfall. But despite that, the last decade was still the warmest decade that we've recorded in Australia," he said.

"We've actually started to see an increase in the amount of stations, weather stations that are recording their monthly maximum temperatures.

"So the highest temperatures on record are occurring with greater frequency and over greater areas of Australia."

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."