Sir

Sujatha Byravan and Sudhir Chella Rajan, in Correspondence (“Immigration could ease climate-change impact” Nature 434, 435; 200510.1038/434435a), argue that major greenhouse-gas emitters should provide compensation for the impacts of climate change.

We believe that compensation is on the cards. We also believe there will eventually be the science to accurately establish liability for those impacts (see M. R. Allen and R. Lord, Nature 432, 551–552; 2004). But the nature of compensation will always remain contested. The notion that migration is a sustainable adaptation strategy for future climate change ignores the fact that patterns of migration are strongly based on social networks and cultural links. Legislating for flows of people may simply not appeal to migrants.

New Zealand's creation of the Pacific Access Category, in response to concerns about climate change, is an instructive example. The scheme allows for up to 75 people from Tuvalu to migrate each year, but since it began in July 2002, fewer than half the places available have been filled. This possibly suggests that even in Tuvalu, where there is widespread concern about climate change, people are not eager to leave their homeland. This example points to the need for policies and measures that help people adapt to climate change, in order to lead the kind of lives they value in the places where they belong, rather than to encourage migration.

The United Nations Framework Convention on Climate Change (UNFCCC) is developing mechanisms to help vulnerable countries adapt to climate change. However, these mechanisms are not the obligatory compensation transfers that Byravan and Rajan espouse. Indeed, the prospect of enforceable migration threatens voluntary processes, such as the UNFCCC, as they may deter large greenhouse-gas polluters from participating in the process.

We believe that promoting and funding activities that enhance in situ adaptation for vulnerable populations is a more practicable and equitable approach than migration-based compensation strategies.