This is a question Dr Jane McAdam, director of international law programs at the University of NSW, is planning to investigate over the next three to four years.

But it is evident from her initial research that apportioning blame under the present international legal framework will be no easy task.

“While moral or factual accountability for global warming may be attributable to particular countries, establishing legal causation and responsibility is difficult,” she told a symposium at the University of NSW last week.

This is largely because global warming has been caused, or is at least partly attributable, to human activity worldwide, and greenhouse gas emissions in one part of the globe will add to the warming of the atmosphere everywhere.

“Environmental displacement is not new; people have always moved in response to variations in their local environment,” she points out. However, climate-induced displacement “as a result of human activities” is novel.

However, international laws that govern the treatment of refugees were not written with environmental catastrophe in mind, but political, racial, religious or ethnic persecution.

So McAdam says there may need to be a re-think of how the international legal system treats people who have become refugees because their country is no longer habitable.

“International refugee law, that whole system is premised on the idea that you will share the responsibility for people that need to be protected,” she said. But it usually relies on a person being able to point to a particular country and say they have been treated unacceptably according to international law.

“That very individualised context just doesn’t seem to be appropriate here, which is why we have to be thinking more globally in terms of general obligations that have been taken towards the international community and think, ‘what are you going to do about these disappearing nations’.”

She cites several major examples where it has been argued people have already been displaced by climate change. One was the disappearance of the island of Lohachara in the Bay of Bengal on Christmas Eve last year, which may ultimately result in tens of thousands of people being displaced by 2020.

Others under threat include the Carteret Islands in Papua New Guinea, which are likely to be submerged in a decade.

McAdam is watching the only significant effort to date to seek reparations for loss of their lands and livelihoods due to climate change.

In March, the Inuit people from the Artic region of North America lodged a claim with the Inter-American Commission on Human Rights in which they say the impacts of global warming caused by “acts and omissions of the US”, has violated their fundamental human rights.

These include the right to the “benefits of their culture, to property, to the preservation of health, life, physical integrity, security, and a means of subsistence”.

New Zealand already has a yearly quota of immigrants it will accept from specific South Pacific nations at risk from global warming. Although McAdam says this program is not officially attributed to climate change, this was the impetus behind it.

Some have suggested people who live in areas likely to be rendered uninhabitable by global warming should be offered a form of asylum by countries that have contributed to their situation. The number of environmental refugees the polluters should be required to take would be proportional to their greenhouse gas emissions.

So, for example, McAdam said scholars in the US had calculated that country would need to take about 866,000 per year, while Italy, the 10th highest emitter, would need to take about 8600.