In 2003, the UNHCR acknowledged the "clear links between environmental degradation and refugee flows".
Projections vary when it comes to the number of humans likely to be displaced as a result of global warming and the related effects of climate change, but no serious observer doubts that it will rise as mercilessly as sea levels.
Earlier this year, economist and climate expert Nicholas Stern said that at the current rate of temperature increase, the environmental refugee crisis is likely to become overwhelming in the coming decades.
"Hundreds of millions of people will be forced to leave their homelands because their crops and animals will have died," he said. It gets worse. "The trouble will come when they try to migrate into new lands, however. That will bring them into armed conflict with people already living there. Nor will it be an occasional occurrence. It could become a permanent feature of life on Earth."
In the High Court at Auckland this week, Teitiota was told that he and his wife, who have overstayed on work visas, must return to Kiribati with their three New Zealand-born children. They are ineligible for asylum, Justice John Priestly ruled, essentially because their claim would not satisfy the requirement of the 1951 Refugee Convention that he would otherwise be subject to "persecution". Crucially, Teitiota has not been mistreated by any "human agency", went the ruling - a conclusion that offers a clue to the dawning 21st century debate over climate asylum: if climate change is attributable to human actions, as the overwhelming majority of scientists agree it is, are those humans, wherever they are in the world, not persecuting those forced from their homes?
Upholding the Immigration and Protection Tribunal decision, Justice Priestly said the case amounted to an "attempt to expand dramatically the scope of the Refugee Convention". The task of adding climate change refugees to the convention is not for courts, he said, but for nation states. Despite, and very probably because of, the scale of the problem, that seems unlikely.
Meanwhile, in New Zealand's neighbourhood, land is melting into the water. The Pacific Islands are the only places in the world where New Zealand is a superpower. And the Pacific Islands, as US Secretary of State John Kerry has put it, are "the front lines of climate change".
John Key has pledged $80 million to address climate change in the region over the next three years, mostly directed at renewable energy initiatives. But his counterparts at the last Pacific Forum in the Marshall Islands, another sinking dish in the ocean, left little doubt that they were deeply unsatisfied with Wellington's contribution.
Only when measured against Tony Abbott's efforts across the Tasman does New Zealand's response to climate change appear impressive. At climate negotiations in Doha last year, New Zealand was awarded a Climate Action Network "Fossil of the Day" prize for joining other developed nations sliding out of the Kyoto Protocol, "running away from a legally binding, multilateral rules-based regime".
But even a dramatic global reduction in carbon emissions is unlikely to save the most vulnerable places in the Pacific. For Kiribati, for Tuvalu, for the Marshall Islands, the most constructive thing that New Zealand can probably do, in tandem with Australia, is commit to welcoming these tiny populations.
For the President of Kiribati, Anote Tong, the task is this: "To plan for the day when (we) no longer have a country." He says: "We want to begin migration now ... We don't have any high ground to retreat to. That is the reality we have to face."
