EACH morning, as the tide recedes, the people of the Marshall Islands check the walls that protect their homes from the sea. Sea levels in this part of the western Pacific are rising by 12mm a year—four times the global average—and countering them with sandbags, concrete and metal is a Sisyphean task. Eight islands in nearby Micronesia have been swallowed by the ocean in recent decades, and most of the Marshall Islands could follow by the end of the century. Here and elsewhere on the world’s fringes, the apocalyptic consequences of climate change have become reality. Many people will be forced to find new places to live. Forecasts vary, but one widely cited study, from the United Nations University, suggests that there will be 200m environmental migrants by 2050. Both migrants fleeing environmental disaster and those escaping war will be constrained in their choices. But currently only the latter may seek refugee status, and with it the right to safe asylum. Why?

On the surface, the problem is bureaucratic. Environmental migrants are not covered by the 1951 Geneva Convention Relating to the Status of Refugees, which is designed to protect those fleeing persecution, war or violence. The UN agencies most involved in refugee rights, the UN Refugee Agency (UNHCR) and the UN Development Programme, agree that the term “climate refugee” should not be used to describe those displaced for environmental reasons. The UNHCR already struggles to provide adequate support for the world’s 22.5m refugees (from war and persecution). During the Syrian refugee crisis, it admitted to being “stretched to the limit”. If the UNHCR broadens its definition of “refugee” to support an entirely new category, it is unclear if the political appetite exists to provide the necessary funding.

Nina Birkeland, senior adviser for disasters and climate change at the Norwegian Refugee Council, says that the process of renegotiating the existing refugee treaty or creating a new one could take decades. Experts also worry that political opportunists, who regard the current refugee convention as being too generous, would use its renegotiation as an opportunity to dilute current obligations. Perhaps more importantly, some of those affected do not want to be called “refugees”. The former president of the central Pacific nation of Kiribati, Anote Tong, resisted the label, stressing that his people wished to “migrate with dignity”. Slowly unfolding disasters brought about by rising sea levels, desertification and droughts result in complex and often gradual patterns of movement. Their victims resist easy classification.

At the same time, New Zealand is set to become the first country to recognise the impact of climate change as grounds for a claim of asylum. The prime minister, Jacinda Ardern, has plans to create a special visa for Pacific Islanders forced to relocate because of rising sea levels. Though the scheme will only offer 100 visas annually, it sets a precedent. Indeed state-led solutions offer the best hope for such refugees. The Platform on Disaster Displacement (PDD), launched in 2016 by a coalition of national governments, will encourage countries to assist these migrants despite the lack of legal recognition of their plight. It builds on a “Protection Agenda” that 109 countries endorsed in 2015, and aims to integrate its principles into national laws. The PDD’s reach is more limited than that of the UN agencies. It cannot create new global legal standards. But supporters argue that it provides the most effective way to organise the necessary resources. With climate change set to cause new waves of migration, states cannot implement new rules quickly enough.