Cradling her newborn baby girl, heatwave expert Sarah Perkins Kirkpatrick admits to feeling torn between the joy of motherhood and anxiety over her first-born child's future.

"I always wanted a big family and I'm thrilled. But my happiness is altered by what I know is coming with climate change," she said.

"I don't like to scare people but the future's not looking very good.

"Having a baby makes it personal. Will this child suffer heatstroke just walking to school?"

Dr Perkins Kirkpatrick is one of several climate scientists who Lateline spoke to, seeking a range of opinions from experts at some of the top climate change research units within major universities in Australia.

The 33-year-old lives in Sydney and studies heatwaves as a senior research fellow at the University of New South Wales' Climate Change Research Centre.

'It was 45 degrees in the shade'

Climate scientist Dr Sarah Perkins Kirkpatrick and her baby girl. ( ABC News: Kerry Brewster )

The youngest of seven siblings, she said she'd always wanted to have at least four, possibly five children.

That was until the record-breaking heatwaves of Sydney's last summer.

"One day I measured 45 degrees outside on the porch in the shade and it was 39 on the inside. The air conditioner in the living room had broken down," she said.

"I was sleeping with wet towels on my legs to keep cool. I was thinking this is hot now and it's only going to get worse.

"I said to my husband 'are we doing the right thing? Is it right to be bringing kids into the world with me knowing how bad it's going to be?'"

'I wouldn't want to live in Brisbane or further north'

How hot could it get? Days hotter than 35C 2014 2090 Brisbane 12 55 Cairns 3 48 Darwin 11 265 Melbourne 11 24 Sydney 3.1 11 Data from 2014 CSIRO and Bureau of Meteorology temperature projections. Figures are based on a scenario in which nothing was done to reduce CO2 and other greenhouse gas emissions.

All of Australia is vulnerable to climate change but Dr Perkins Kirkpatrick said as the decades progress, some regions will be better off than others in terms of heatwaves.

"We've already seen changes in heatwaves, particularly their frequency, and these heatwaves are only going to get worse, particularly in the tropics, where the number of heatwave days will be much greater than now," she said.

She said research shows that if there isn't a reduction in CO2 emissions, there will be up to 50 extra really hot days a year in northern Australia by the end of the century.

"I wouldn't want to be living in Brisbane, north of Brisbane, over the coming decades because the humidity will be atrocious and when it's hot and humid it's actually a lot harder to stay cool because your body can't get rid of that heat through evaporation," she said.

"There's nowhere for the moisture to go."

'Adapt or die'

Professor David Griggs, who recently retired as director of the Sustainable Development Institute at Monash University, said Australia is in denial about climate change.

"Australians will have to adapt or die," he said.

He believes temperatures will rise well above 2C and may reach 5C above average by the end of this century, a forecast in line with the UN's IPCC modelling under a high emissions scenario.

He spoke to Lateline about the emotional burden of knowing what climate change would bring.

"Depression is clearly something. You get days when you're down, because what you know and what you can see coming is not good," he said.

He is planning to move his family to south-west England, where he said climate projections look good for the next 100 years.

"When a new fact comes in that makes me fearful I think at least I've done what I can to protect my family," he said.

Climate scientists moving south

PhD student Justin Oogers said he and his wife were also unsure of whether to have children.

"We're quite concerned, even scared. Our parents want us to have children and there are great things about having children but knowing what's happing with climate change we've been putting it off," he said.

He said they have considered moving further south to Tasmania.

"We may be forced, my wife and I, to move further south. A lot of other people are probably thinking the same thing," he said.

"My grandpa, he's living on a boat south of Hobart."

Dr Perkins Kirkpatrick said her family is making contingency plans and may move from Sydney.

"My husband and I have raised the possibility of moving to Canberra. It's a city, it has good employment opportunities, good infrastructure. Their night time temperatures are a lot cooler because they're further inland," she said.

"You can cope with extreme heat much better if you have cooler night time temperatures to sleep."