Dr Khalid Koser is Head of the New Issues in Security Program at the Geneva Centre for Security Policy, and a non-resident Fellow at the Lowy Institute.

Bloggers, government officials, academics, and radio interviewers have kindly (and in one or two cases, not so kindly) responded to my paper, published last week by the Lowy Institute, arguing for a national policy on environmental migration.

Three arguments against my recommendations have recurred.

First, why should Australia respond yet again on a unilateral basis to a multilateral problem? Doesn't Australia already do more than its fair share for refugees with its recent commitment to increase its resettlement quota to 20,000? And didn't Australia, along with the EU and a handful of other countries, save the Kyoto Protocol in Doha last week by agreeing to further cut carbon emissions?

Yes. But the resettlement quota won't cover the number of people who in the worst case scenario may be displaced from Pacific Island countries and head for Australia illegally if there is no other way. And surely the lesson from Doha – as from Copenhagen and Cancun – is that UN negotiations on climate change proceed at a glacial pace. Faced with the prospect of significant environmental migration in the next decade or so, Australia can't afford to wait for the UN.

A second concern has been about numbers. Academics have warned me against speculating, in some cases because of the question marks that remain about climate change science, and in others because of the fear of whipping up anti-immigration reactions. In contrast, media outlets have requested specific (and preferably large) estimates.

My paper cites estimates from fairly reputable sources for how many people may be affected by climate change in Pacific Island countries, and provides reasons why a proportion of them may be expected to leave their countries and head for Australia. But if any country in the world has demonstrated that the political significance of migrants outweighs their numerical significance, it is Australia, where a few tens of thousands of boat arrivals over the last few years have spectacularly dominated politics and policy. Even the most conservative academic wouldn't baulk at estimating that tens of thousands more may arrive from Pacific Island countries as a result of climate change.

Third, it has been argued that the Australian Government is too preoccupied with the current migration agenda and responding to the recommendations of the Expert Panel on Asylum Seekers to expend new resources on a distant problem, and what's more for a policy that will likely admit more rather than fewer people.

I fully acknowledge that the political climate in Australia is not conducive to expensive new legislation on migration, or to policies that risk Australia becoming a magnet for environmental migrants. (It still amazes me that this is the case in the country with, in my opinion, the best managed migration system in the world; how did the government allow a good news story to become such a bad news story?)

But after reviewing a number of policy options in the paper, my recommendation is to extend the existing Pacific Seasonal Worker Programme, thus allowing Australia to determine the countries and people who might be included in any legislation on environmental migration, their numbers, profile, and the conditions for their entry and stay.

Having heard the arguments, I still maintain that developing a national policy on environmental migration is not an exercise in speculation: it is managing a future challenge and it is in Australia's national interest.

Photo by Flickr user Jacek Sniecikowski.