The world's climate is changing. And at a pace that has been increasing since the start of the industrial revolution.

Experts from the Intergovernmental Panel on Climate Change (IPCC) have established that average temperatures in the Northern Hemisphere were significantly higher during the second half of the 20th century than in the previous thirteen centuries. In the Arctic region alone, average temperatures have increased at almost twice the global rate in the past hundred years.

Although some may still refuse to recognize it, evidence shows that human activity is largely responsible for these changes and that they are increasingly affecting population movements.

Of course migration has always been one of the possible adaptation strategies for people facing gradual environmental changes or natural disasters. In some areas, it has even become a way of life. But today, we have reached a critical point. The international community has started to take the issue seriously, an issue which is complex and still not well understood because it requires bringing together several perspectives, including environmental, climate science, sustainable development, humanitarian action, human rights and migration.

Although we don't know how many people will migrate over the coming decades for environmental reasons as this is very much dependent on our capacity to reduce greenhouse gas emissions, one thing is certain – the number of these people will continue to grow.

With this knowledge, the spectre of a "new human tsunami" is just one step away.1 It may certainly be politically tempting to surf the "security wave" and argue that climate change will inundate the shores of the developed countries with millions of people in search of less hostile environments. Such arguments could be used as a justification for even more restrictive migration policies. Given the anxiety brought about by the current economic downturn, such policies are likely to be welcomed by the public.

However, such political shortsightedness does not stand up to reality.

First of all, recent studies, albeit limited in geographical scope, confirm that most environmentally-induced migration will be internal, either towards the illusory promise of prosperity in cities or towards other rural areas still able to provide sustenance to the affected communities. Cross-border movements might be another important trend, especially in regions where the notion of a "border", although used by States, is not well recognized by local populations.

Secondly, it is likely that international migration linked to climate change will be very limited for the simple reason that migration requires financial resources and/or community networks in the destination countries, which the poor and the "landless" do not usually have.

Finally, if the policies to combat irregular migration in all its forms are to be effective, they need to be accompanied by the opening up of regular migration channels on the conditions agreed among the relevant partners. Without such a global and concrete approach, clandestine channels and unscrupulous smuggling networks are often the only option available with the dramatic and unfortunate consequences that so often make the headlines.

A further complicating factor is the difficulty of identifying or "labeling" environmental migrants. Except in cases when natural disasters force people to move in order to survive, it is usually difficult to single out climate change or environmental degradation in a combination of socio-economic and political considerations that are behind the decision to move. This is probably why environmental migrants do not benefit from a distinct status under international law.

Considering the utmost caution, not to say the reluctance, with which most States approach the establishment of new categories of people entitled to specific rights, this is unlikely to change in the near future. In the migratory flows that reach developed countries, environmental migrants are indistinct from economic migrants and share the same fate. Asylum claims made by some are systematically rejected.

The reason is simple. People moving for environmental reasons are not "climate refugees", even though the media continues to use this term because of its strong emotional connotation and the compassion it generates. Words do have a meaning, and the 1951 Convention Relating to the Status of Refugees clearly states that the notion of persecution is central to the eligibility of people for this status. This limits the possibility of granting a refugee status in the context of environmental degradation to few very special cases. In a few countries, Temporary Protection Status (TPS) was established to assist foreign populations affected by natural disasters. Hurricane Mitch led the United States to offer temporary protection, an example followed by Sweden and Finland with different conditions of eligibility.

Natural disasters affect populations in many ways, yet it is important to remember that 98 per cent of all deaths related to natural disasters occur in developing countries. It is this image that comes to mind first – human drama, hundreds or thousands of deaths and the need for the humanitarian emergency response. In most cases, mass displacement linked to such phenomena are temporary and paradoxically, the returnees tend to rebuild their homes in the same place where they lived before the disaster struck. This despite the likelihood of something similar happening again and the advice of the humanitarian community.

It is true that the number of extreme events has doubled over the past 20 years, from 200 to more than 400 a year. Yet, climate change is also triggering other, more subtle and gradual changes that are expected to lead to more permanent displacement over the next decades.

These changes include increased desertification, soil erosion, deforestation, rising sea levels and the salinization of water resources. In this context, the key word is, no doubt, "adaptation". Yes adaptation at or close to the homes of affected populations if feasible, but we have to accept that migration remains today, as it has since time immemorial, a mechanism to adapt to change.

Therefore, the international community's response must also adapt to this new paradigm. It may be easier to raise funds to respond to natural disasters because of the emergency nature of such events and because of the media coverage and the political credit such assistance can bring. However, it is much more difficult to convince donors to invest in tackling the long-term effects of climate change and to support adaptation as the effects of such investments are not evident for many years. They are less "saleable" to the public. This is particularly true in the current difficult economic climate, where voters are more concerned about keeping their jobs and maintaining their standard of living.

The moment of truth will come in Copenhagen, during the next United Nations Framework Convention on Climate Change (UNFCCC) Conference of the Parties.

As well as the need to come to an agreement on reducing greenhouse gas emissions, the manner in which climate change adaptation is addressed will determine our actions on the ground for at least the next decade. Will negotiators be willing to consider the humanitarian implications of climate change - including migration and displacement - not just as a simple corollary of climate change but as central to our ability to guarantee human security?

It's a gamble – risky but worthwhile.

1 Liberation forum (20-21 September 2008) held a debate on the theme "Climate refugees: a new tsunami?"