Attention Tim Flannery. Immigration is good for the environment.

Apparently there was an IQ2 debate at the City Recital Hall last night, on whether Australia should decrease its immigration rates. Attentive readers would already be aware my answer is a resounding no.

Those who are opposed to increased human population due to its effects on the environment, such as our esteemed 2007 Australian of the Year, have attained the honour of provoking a response from me today. (I might get around to applying a blowtorch to the even more terrible arguments about the labour force or social cohesion on another occasion.)

Its one thing to argue that the Earth can't sustain more people or indeed even our current population. I happen to think it is absurd to argue this; I won't respond to it, though, because the stated case I am refuting is even weaker.

Why? Because immigration does not create more people, magically, out of thin air (as of 2009 there is so far only one technologically mature process for doing so.) It simply moves them. And it doing so, it actually reduces the projected future population of the world. So if we really are approaching the limits of our finite carrying capacity, immigration is actually a Good Thing (TM).

How can immigration reduce future population? Despite popular stereotypes to the contrary, descendents of immigrants assimilate to the culture of their adopted home. Actually the culture also assimilates to them, but this effect is much smaller when immigration is low relative to the size of the population.

Now Australia is in the 5th phase of what's known as the demographic transition. Our natural fertility rate is negative. People immigrating here are typically from countries in the 2nd, 3rd and 4th phases of the transition. If they stayed in their home countries, they would ultimately have far more descendants than if they move here, where many of their great-grandchildren are likely to end up childless.

Of course, Australia's natural resources will end up a little more strained, certainly relative to the rest of the planet. I hope it goes without saying, though, that we all care first and foremost about the global environment, and aren't just seeking to keep our own little island free from populaion pressures. It does go without saying? Excellent.

"Ah", the environmentalist now argues, "but rich people - such as immigrants in a first world country - are far worse for the environment than poor people, such as their cousins left behind."

This rebuttal, for the time being, is true. It is morally abhorrent - it implies that to protect the environment, we should actively seek to prevent the world's poorest people from becoming any richer, while it is implied Westerns be allowed to continue to enjoy tremendous wealth (even the most eco-concious Australian is both far richer and more polluting than most Ethiopians) - but it is nonetheless grounded in fact.

Except the rest of the world is steadily becoming richer, regardless of whether we let people migrate here or not. China and India will eclipse the West's ecological footprint relatively soon, and other developing nations are sure to follow. Meanwhile, the West has actually started to wake up to the issues facing our environment, and furthermore has the luxury of being able to sacrifice some of its vast wealth on attempts to try and save the planet from oblivion.

What is more likely to save the world from climate change? An argument to convince the populations of third world countries that they don't need electricity? An enlightened political consensus leading to enforcable international laws that constrain our carbon emissions? Or scientific breakthroughs, funded by Western economic growth, that lead to both cheap, clean energy sources, and the ability to extract exisiting anthropogenic greenhouse gases from the atmosphere?

You don't have to believe technological progress is a panacea for the world's problems; just that it has a better track record than self-righteous moral preaching or complex political compromies.

Without loss of generality the argument holds for shrinking bio-diversity, loss of arable lands, etc.

Sadly, Malthus remains an influential voice in today's public policy debates, despite more or less 200 years of consistent empirical evidence refuting his ideas. I guess all that's left to be said is: Bring on the next lot of people to add yet more nails to his theories' coffin, and maybe one day people will get the picture.

Here's hoping they include plenty of Indian computer scientists developing smart grid technology for Google in California, Brazilian geneticists engineering algae to convert C02 and sunlight back into fossil fules for the CSIRO in Canberra, and Ghanian economists at the LSE publishing solidly researched papers backing up the case made here with scientifically rigorous evidence.