A Pacific islander whose homeland is threatened by rising seas failed in an attempt to become the world's first climate change refugee Tuesday, with a New Zealand judge dismissing his case as "novel" but "unconvincing".

Lawyers for Ioane Teitiota, 37, argued that New Zealand should not deport him even though his visa had expired, because climate change was gradually destroying his low-lying home in Kiribati.

The difficulties Teitiota and his family would face in the tiny nation -- which consists of about 30 atolls, most only a few metres above sea level -- meant they should be recognised as refugees, the lawyers said.

In a written ruling handed down on Tuesday, High Court judge John Priestley acknowledged that Kiribati was suffering environmental degradation attributable to climate change, including storm surges, flooding and water contamination.

But he said millions of other people in low-lying countries were in a similar situation and Teitiota did not qualify as a refugee under international law.

Priestley said the UN Refugee Convention stated that a refugee must fear persecution if they returned home, a criteria Teitiota did not meet.

"The economic environment of Kiribati might certainly not be as attractive to the applicant and his fellow nationals as the economic environment and prospects of Australia and New Zealand," he said.

"But... his position does not appear to be different from that of any other Kiribati national."

The judge rejected the argument from Teitiota's legal team that he was being "persecuted passively" by the environment because climate change was a threat to him that the Kiribati government was powerless to control.

"Novel and optimistic though these submissions are, they are unconvincing and must fail," Priestley wrote.

"On a broad level, were they to succeed and be adopted in other jurisdictions, at a stroke, millions of people who are facing medium-term economic deprivation, or the immediate consequences of natural disasters or warfare, or indeed presumptive hardships caused by climate change, would be entitled to protection under the Refugee Convention."

He said there had been numerous similar claims under international law for climate change refugee status by people from countries such as Tonga, Fiji and Bangladesh, none of which had succeeded.

"It is not for the High Court of New Zealand to alter the scope of the Refugee Convention in that regard," he said. "Rather that is the task, if they so choose, of the legislatures of sovereign states."

He said Teitiota and his wife moved to New Zealand in 2007 and chose to stay illegally because it offered a better future than Kiribati.

They had three children who were born in New Zealand but they will also be deported because the offspring of illegals born in the country are not recognised as citizens.

Kiribati is among a number of island states -- including Tuvalu, Tokelau and the Maldives -- which the UN Human Rights Commission is concerned could become "stateless" due to climate change.

Kiribati's government has raised the prospect of relocating the entire population or building man-made islands to rehouse them if predictions that the sea will rise by one metre by the end of the century prove accurate.

It has also moved to buy 2,000 hectares (5,000 acres) of land in Fiji to act as a farm for Kiribati if salt-water pollution means the islands -- a former British colony -- can no longer produce crops.

Teitiota's lawyer was not immediately available for comment on the ruling.