Floods, bushfires and this year's scorching summer heatwave have raised awareness of the dangers of climate change, but an "infantile" debate over the validity of the science has cost Australia precious time, according to a key Climate Commission expert.

The commission, an independent body that advises the government on climate science, has updated its 2011 The Critical Decade study to analyse the latest findings on climate change and Australia's response to it.

The report is likely to be the Climate Commission's last major contribution if, as expected, the Coalition wins power at the 14 September election. Opposition leader Tony Abbott has signalled that he will scrap the commission , along with the carbon price, if he becomes prime minister.

The commission's updated analysis states that evidence of a "rapidly changing climate has continued to strengthen over the last two years", including, importantly, the link between climate change and extreme weather events.

"It is clear that the climate system has already shifted, changing conditions for all weather," says the study. "While extreme weather events have always occurred naturally, the global climate system is hotter and wetter than it was 50 years ago. This has loaded the dice toward more frequent and forceful extreme weather events."

In Australia, this has manifested itself in an increase in the duration and frequency of heatwaves, such as this year's .

The country is now also more prone to "extreme fire weather", especially in the densely populated south east, changing rainfall patterns and increased coastal flooding from sea level rises.

The report warns that this climate shift "poses substantial risks for health, property, infrastructure, agriculture and natural ecosystems", with Australia largely "ill-prepared to cope" with frequent extreme weather events.

However, the report states that the last two years has seen an increased understanding of the challenges posed by climate change and also the action, such as leaving the majority of buried Australian coal resources untouched, required to help the world stay below the internationally agreed temperature increase limit of two degrees above pre-industrial levels.

"Extreme weather events tend to focus the mind and change the narrative around climate change," Professor Will Steffen, of the commission, told Guardian Australia.

"The IPCC report that linked extreme weather events to climate change in 2012 was a breakthrough as previously scientists were loathed to link the two. I've certainly noted that when I go up to Queensland, people are fed up cleaning up a once in a 100-year flood and then doing it again next year. People are starting to ask what's going on."

Steffen said that Australia had made progress in its bid to reduce emissions but that vital time has been wasted in the questioning of the validity of climate science.

"I'd love for us to be at the point where Nordic countries are, where the science is accepted in a bipartisan way and the debate is around how to get emissions down," he said.

"I think we've lost valuable time with an infantile debate over the science, which has delayed the inevitable work of getting to the solution. There have been attempts to undermine the science. The science has been attacked and scrutinised and it's stood up."

"Australia is moving to the middle of the pack internationally in terms of what countries are doing on climate change. That's partly due to the carbon price, but also the renewable energy target, energy efficiency and the price of solar PV dropping so people are putting it up solar panels."

"But global emissions are still going up. There are positive signs in Australia but we make it clear in the report that we all need to do more and need to do it quickly."

The Climate Commission report states the best estimate for average annual land warming across Australia to be one degree by 2030, compared to the 1980 to 1999 average. However, with around 90% of the planet's extra heart soaked up by the oceans, rising sea levels and the impact on ecosystems such as the Great Barrier Reef will also prove significant.