We need to start preparing for retreat rather than leaving it until it's too late, researchers say.

From Bangladesh to the Philippines and the low-lying islands of the South Pacific, the impacts of climate change for many people around the world are going to get much worse, very soon.

Key points climate retreat Key points Preparing now can prevent last-minute disorderly evacuation from climate impacts

Building in areas that will be hit by climate disasters in future needs to stop

Millions are expected to be displaced by the end of the century

Some people will become stateless, and will need to find homes in new countries, while others will need to relocate within their own borders.

Researchers writing in Science today argue that it's time to begin preparing the retreat of people living in regions that will become uninhabitable due to climate change.

By preparing now we can manage retreat in as equitable a way possible, and minimise paternalism and disruption to culture, according to author AR Siders from the Disaster Research Centre at the University of Delaware.

"People need to think about it right now," Dr Siders said.

"We've already seen examples of when hazards happen, it is unorganised and it causes more harm than it needs to."

Average global sea level will rise by up to 77 centimetres by the end of the century if warming is kept to 1.5 degrees Celsius, according to IPCC predictions.

If warming reaches 2C, that is likely to be around 10 centimetres higher, displacing around 10 million more people worldwide.

According to the IPCC, we're on track to hit 1.5C of warming between 2030 and 2052 at our current rate.

Extreme weather events, saltwater incursion and bushfires are also expected to displace people in the near future.

Before and after flooding on the Gold Coast due to climate change Share High tide inundation on the Gold Coast in 2018. Share High tide inundation on the Gold Coast in 2100.

But we need to start small, and get the fundamentals right, Dr Siders argued.

"Some places absolutely will require cross-border relocation and managed retreat, but in other times we're talking about relocation from one Australian community to another — so dealing with people who are on the coast in a vulnerable place, or they're too near to bushfire risk," she said.

"It's really also a conversation about where we should build as well as how should we build."

Like most scenarios though, prevention is better than cure.

While it is widely thought to be too late to avoid warming of at least 1.5C, Griffith University adaptation scientist Johanna Nalau said we can avoid building in areas we know will become uninhabitable in the future.

"We have a lot of population on the coast. The smart thing would be to start having these discussions when it comes to building new infrastructure and investment," Dr Nalau said.

Coastal regions like Miami in the US are already starting to see property values drop as houses get harder to insure, she added.

Part of our retreat strategy needs to manage the relocation of people currently living in low-lying areas in ways that don't leave them financially destitute.

Developers 'not paying for the recovery' after disasters

Share Parts of coastal Australia will eventually have to be abandoned.

But there are competing interests between property developers and house buyers.

Developers currently suffer no consequences when poorly planned housing developments are hit with foreseeable natural disasters, Dr Siders argued.

"It's a challenge of who has the incentive to build and who bears the risk. Developers can come in and build and then they're gone before the next flood comes," she said.

"They're not living through the flood, they're not dealing with the harms, they're not paying for the recovery afterwards.

"That's left on the people who actually live there or the taxpayers who are funding that recovery and mitigation for the next disaster."

There has been some effort in Australia already to limit coastal development.

Future climate conditions and their potential impacts have been discussed for development to varying degrees in different parts of Australia for the last 10 years or so, according to Dr Nalau.

"We have been trying to develop more robust planning practices in different states, to make new investments and new infrastructure on the coast to better withstand impacts from climate change," she said.

But as was made clear at the Pacific Islands Forum in Tuvalu last week, many in the South Pacific fear they will soon lose their countries.

In that case, Australia will be one of the countries in the region that people will be likely looking to resettle in.

Planning for that eventuality, whilst also reducing emissions now, could help make that transition easier and more equitable.

"The question at the moment from a Pacific Island viewpoint is, why is Australia opening new coal mines...as these will accelerate climate change globally, with severe consequences to Australia and all other countries," Dr Nalau said.