What they are not mentioning about immigration.

If you are under the impression that lowering skilled immigration to around 180,000 per year will result in our population being less than 36 million in 2050 you're wrong. The numbers both parties are using come from the Intergenerational Report 2010 (IGR). That report says that if we increase skilled immigration to 180,000 per annum we should reach 36 million by 2050. Opposition Immigration spokesman Scott Morrison actually acknowledged this in the initial immigration debate on the ABC. But somehow, in the general spin of an election campaign the message of the IGR got twisted into almost its exact opposite.

The IGR is also quite clear in showing that if its predictions are right, even this level of immigration will not necessarily ameliorate the effects of the problem the IGR was set up to look at in the first case. That is, the problem of Australia's ageing population.

Using migration and total population estimates from the IGR while failing to realise the framework problems the IGR is actually reporting on gives the electorate only half the story. The small half of the story.

The big part of the story is that even if we keep up that level of skilled migration, by 2050 there will be only 2.7 working aged people to every person aged over 65. Today there are 5 working aged people per aged person. And in 1970 there were 7.5 working aged people per aged person.

This is the reality that underpins our population problems. We need more people in order to support our ageing population, yet we are unwilling to accept more people if that means more congestion and further harm to our natural environment.

But unless we can more than double the productivity of every working aged person by 2050 we really have no choice other than to grow the population.

Of course, we could figure out some way of removing more old people. Labor have gone somewhat down this path by simply raising the retirement age for anyone who is currently under 52. But even this measure, implemented between 2017 and 2023, will not give us anything like the space we need to solve the problem.

It is also worth noting that we are not alone in this. Most of the Western World faces similar problems with an ageing population. This means the people we bring into the country to fill the gap will almost certainly come from China, India and South East Asia. Recent changes to migration rules are not doing anything toward making us a more attractive, or even viable, destination for people from these regions.

But in the medium term we must engage with these people. It is also in our long-term interest to design and implement a steady and predictable migration program, not one that changes with the short term election cycles as its primary motivation. The sooner we start bringing these people in, the longer their communities will have to assimilate and settle into the broader Australian community.

We also need the time to build infrastructure, and avoid the environmental impacts of having more people here.

The problem then is not about if we want to have a population of 36 million in 2050, but how we can reach that number while preserving our natural environment, providing adequate infrastructure and, while we're at it, doubling the productivity of the people. That is a challenge. Pretending to simplify this problem to mere number trading and racial dog-whistling does the electorate no service.