The biennial State of the Climate report pulls together the latest climate monitoring and science to reveal how the climate is changing.
CSIRO Climate Science Centre interim director Steve Rintoul says the findings line up with evidence of climate change.
"And the primary driver is the increase in carbon dioxide measured in the atmosphere. Since 1975, carbon-dioxide levels have increased pretty steadily. The concentration of CO-2 in the atmosphere is now 44 per cent higher than it was in 1750 and is likely higher than it has been at any other time in the last two million years. As a consequence of that increase in carbon dioxide -- carbon dioxide is a greenhouse gas -- the additional carbon dioxide has enhanced the greenhouse effect and the earth has warmed."
The Bureau of Meteorology's Manager of Climate Monitoring, Karl Braganza, says Australia is already experiencing the effects of climate change with record-breaking heat.
Dr Braganza says it is now becoming commonplace around the country.
"So that's a really big change in terms of, from our perspective, all the operational agencies that might be dealing with fire, weather and heatwaves across more than one state at one time. So, these events would come around relatively infrequently -- at most, once or twice a year, but, really, there's many years where we didn't get any such days. In the last period, what we've seen is, really, a stacking up of these days, so a much higher frequency of this kind of extreme heat."
The report says Australian temperatures will continue to rise over the coming decades, with more extremely hot and cool days.
While rainfall has spiked across parts of northern Australia since the 1970s, the country's south-west has seen falls reduce by up to 20 per cent.
Dr Braganza says rainfall and extreme heat are key factors that contribute to more devastating fire seasons.
"What we've seen is both an increase in the extreme fire weather, so it's becoming more extreme, and we've seen more fire weather throughout the fire season, and that's associated as well with a longer fire season. So we're seeing fire weather push into spring and autumn, and, particularly in spring, that's been associated with early-season heatwaves that have come through. "
Dr Braganza says sea-level rises will continue and the oceans around Australia will continue to warm, influencing the overall climate of the country.
He says Australia's tropical cyclones will also be different, likely to decrease in number but increase in intensity.
"When we talk about intensity in tropical cyclones, we're mostly talking about wind speed, and changes to wind speed are expected to really become apparent later this century. Something to note, though, with tropical cyclones is a lot of the damage in Australia gets done by storm surges and intense heavy rainfall, and those things are expected to increase proportional to global warming. So we're expecting those changes to be occurring now and ongoing."
Dr Braganza says some of the record-breaking heat seen in recent times will be considered normal in 30 years.
But the CSIRO says awareness of climate change and its implications is also improving.
Steve Rintoul says the appetite and demand for better scientific information is growing rapidly.
"That's an indication, I think, that the community and decision-makers in government, in industry and in the community are engaged with the issue and are looking for the best information they can get to make some of the tough decisions that they have in front of them."
