Richer nations don't necessarily need to build walls around poorer nations to keep the water out. They may find it cheaper or otherwise preferable to build walls around themselves to stop the flow of people fleeing from the poorer nations.
Climate refugees have no legal status under the UN Refugee Convention:
> `there has been a collective, and rather successful, attempt to ignore the scope of the problem... so far there is no "home" for forced climate migrants in the international community, both literally and figuratively` -- Oli Brown [1]
Nations are already following this approach of literally building walls or pouring resources into improving their border security. For example, India is building a wall along its border with Bangladesh, and some of the nations in the EU are spending a lot of money and resources trying to intercept or discourage boats of immigrants from Africa [2].
> With 80 percent of its densely populated landmass lying near sea level, Bangladesh is often hailed as "ground zero" for climate change. A 1 meter rise in sea level, which seems likely by the end of the century, could flood almost one-fifth of the country. Some of the most vulnerable coastal districts in Bangladesh—Khulna, Satkhira, and Bagerhat—lie along India's border. -- [3]
> The Continent's richer, more northerly countries, great emitters of carbon and producers of wealth, barely contributed ships or aircraft to Frontex [4], and they processed a relative trickle of African asylum seekers. So Malta was itself a victim to this, he suggested. It was a power game: Northern Europe bullied southern Europe. Southern Europe fought within itself and with or against North Africa. The big stepped on the small, and the small stepped on the smaller. The migrants themselves were at the bottom. Here, too, shit rolls downhill. -- [2]
edit: as usual, I'm not writing this because I advocate this position, or think that it has any moral or ethical merit. But I think it is good to clearly understand that this is already happening and it will almost certainly get worse the further we get into this century.
And I did not write what I did because I'm unaware that those that make the argument that "it would be cheaper to adapt" never publicly add "... for us", because the argument gets a lot less palatable if you admit that your plan is to let the peoples of the developing world drown or starve to death...
Climate refugees have no legal status under the UN Refugee Convention:
> `there has been a collective, and rather successful, attempt to ignore the scope of the problem... so far there is no "home" for forced climate migrants in the international community, both literally and figuratively` -- Oli Brown [1]
Nations are already following this approach of literally building walls or pouring resources into improving their border security. For example, India is building a wall along its border with Bangladesh, and some of the nations in the EU are spending a lot of money and resources trying to intercept or discourage boats of immigrants from Africa [2].
> With 80 percent of its densely populated landmass lying near sea level, Bangladesh is often hailed as "ground zero" for climate change. A 1 meter rise in sea level, which seems likely by the end of the century, could flood almost one-fifth of the country. Some of the most vulnerable coastal districts in Bangladesh—Khulna, Satkhira, and Bagerhat—lie along India's border. -- [3]
> The Continent's richer, more northerly countries, great emitters of carbon and producers of wealth, barely contributed ships or aircraft to Frontex [4], and they processed a relative trickle of African asylum seekers. So Malta was itself a victim to this, he suggested. It was a power game: Northern Europe bullied southern Europe. Southern Europe fought within itself and with or against North Africa. The big stepped on the small, and the small stepped on the smaller. The migrants themselves were at the bottom. Here, too, shit rolls downhill. -- [2]
[1] http://www.ibanet.org/Article/Detail.aspx?ArticleUid=B51C02C...
[2] see the book: "Windfall: the booming business of global warming" by McKenzie Funk.
[3] http://www.slate.com/articles/health_and_science/green_room/...
[4] https://en.wikipedia.org/wiki/Frontex
edit: as usual, I'm not writing this because I advocate this position, or think that it has any moral or ethical merit. But I think it is good to clearly understand that this is already happening and it will almost certainly get worse the further we get into this century.