David Blaker: Auckland growth predictions exaggerated

Debate over Auckland's future has presented us with an unattractive choice: build up or build out. Either a rash of high-rise in suburbia, or outwards sprawl into surrounding farmland. But it's a false choice, based on the Unitary Plan's belief that Auckland is " ... projected to increase by one million over the next 30 years". This blunt statement is contained in one sentence in section 1.3.1, accompanied by not a scrap of supporting evidence.

Their projection is unrealistic. Bernard Orsman's feature in the Herald last week provides a breath of fresh air by taking a critical look at the supposed reality of an extra one million, leading to an Auckland population of around 2.5 million by 2030.

So what is the evidence? The basic facts are set out in Statistics NZ's website and in their Yearbooks. Future population can be predicted quite accurately from rates of natural increase (births minus deaths), combined with migration.

New Zealand is one of the very few countries to have total control over immigration. We have no boat people, few asylum seekers, none of the cross-border people-smuggling that torments Europe. Migration is good but it's not an irresistible force of nature. New Zealand is a hard country to get into and gaining permanent residency is a major hurdle. Statistics reports an overall net gain of 65,004 "permanent and long-term arrivals" in the five years up to 2011. An average gain of 13,000 a year into the whole country is hardly a flood, and government could reduce inflow at the stroke of a pen.

And what of natural increase? Since 1981 net fertility has been at or slightly below replacement level, with an average of two children per woman, in contrast to the average of 4.3 children in the late 1950s. Just as important, childbirth is being delayed. The median age of childbearing in 1973 was 25 years; by 2003 it was over 30 years.

It is wildly unlikely that New Zealand women will collectively revert to the reproductive enthusiasm of the 1950s. If fertility and net migration are both low, then why has our population kept increasing? Simple: it's due to the baby boom of those fecund post-World War II years. However, they will pass. Us baby boomers are just as mortal as everyone else, and we are starting to die off.

Auckland is a special case, having experienced steady migration from other parts of the country. New Zealanders are highly mobile. People will continue to move in and out of Auckland from elsewhere in New Zealand, basing their decisions on whether jobs and living conditions are attractive enough to offset the drawback of high house prices. The big question remains: how many people?

The projection from Statistics is that nationwide population will touch five million around 2030 - an increase of just under 600,000 on present numbers. The Unitary Plan predicts an increase of one million for Auckland, which means that almost 50 per cent of the nation's population would be living here by then. Really? Will all of the 600,000 increase (plus 400,000 more) decide to settle in Auckland? All evidence suggests this won't happen.

Even if population increase turns out to be less than half the Unitary Plan's "extra million", even if floods of expatriate Kiwis return home, wouldn't it be great if Auckland had a satellite city with good infrastructure, good transport links, plenty of available space? Actually it does: Hamilton. Many people are already voting with their feet and heading for dozens of places where living conditions are better and house prices lower.

It is right and proper that Auckland Council takes the long view, but we need to see the "extra million" prediction for what it is: highly exaggerated. And why should projections and vision extend only 30 years? Nationwide statistics show our population levelling off at 5.5 million around mid-century.

That may seem distant but it's not; the 165 babies who will be born tomorrow across the country will be only 37. Instead of being panicked into planning for an extra million people who won't arrive, we should be asking ourselves basic questions, such as "What kind of city and country do we really want?"

David Blaker is a science writer based in Auckland.