New Zealand is said to now experience a damaging storm on average every eight days, a frequency that has more than doubled in the last decade.

Insurers are starting to charge higher premiums for houses on floodplains or cliff-tops. So a house may still be "insurable", but the premium makes it effectively unsaleable.

"You own a house, but you can't do anything with it,” says Boston. “You can't move because you haven't got any assets to move to.

“You've acquired a risk that you knew nothing about... and if your work is vulnerable as well, you're potentially going to be bankrupt.”

Many of those trapped, bought homes on the understanding of having clean Land Information Memorandums (LIMs) - only to then have updated climate modelling render their homes vulnerable.

“Someone may have bought it 30 years ago in good faith, with no indication of river flooding or sea level rise,” Boston says.

“Then the climate system changed. We are faced with risks of a magnitude humanity has not had to cope with since the end of the Ice Age."

The Insurance Council said reducing risk through smarter planning, resilient infrastructure, and better information was essential to ensure insurance remained accessible and available.

New Zealand has a balanced approach through a mix of private and public insurance via the Natural Hazards Commission.

He tells the Sunday Star-Times that New Zealand faces a stark political choice between two paths:

• The Market Route: Risk-based pricing where individuals are responsible for their own assets. If you become uninsurable, that is "bad luck".
• The Solidaristic Route: A collective risk-pooling approach where the state and society share the burden to maintain social cohesion.

“We need to decide whether we're going to link the price of insurance to the risk... or address those risks collectively in a systematic and equitable way,” Boston says.

“The politics are diabolical. Some people are just wilfully blind, including some of our political leaders, to the magnitude of the risks we face."

While physical adaptations like raising houses on stilts exist, Boston notes they are rarely cost-effective against accelerating sea levels.

He advocates for a "paradigm shift" involving the Natural Hazards Commission to facilitate planned relocation where protection isn't feasible.

“We have the capacity to make ethical, rational decisions,” he says. “Whether we demonstrate that capacity is another matter. Plainly, we're not doing very well at the moment.”

He says his book aims to re-fashion policy frameworks, to take into account we're entering a new age, and can't just rely on previous policy arrangements we've had.

“You've got ideological or philosophical differences over how you might respond, even if you accept that we've got unprecedented risk,” he says.

“All those things make it difficult to get a durable multi party agreement. We do have the capacity as a human species, to take risks seriously, to exercise foresight, to do really good policy analysis and to make ethical, cost effective, rational decisions.

“We have that capacity, whether we demonstrate that capacity is another matter. And plainly, we're not doing very well at the moment. We do not have in place the kind of policy framework we need.”