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Subnational Population Projections: 2006(base)–2031 (October 2012 update)
Embargoed until 10:45am  –  08 October 2012
Commentary

Important advice for using projections

Subnational population projections give an indication of the future population usually living in the 16 regional council areas (regions) and 67 territorial authority areas of New Zealand. Three projections (low, medium, and high) incorporating different fertility, mortality, and migration assumptions for each geographic area have been produced to illustrate a range of possible scenarios.

At the time of release, Statistics NZ considers the medium projection suitable for assessing future population changes. The medium series is consistent with the median projection (50th percentile) of the National Population Projections: 2011(base)–2061 (released July 2012). However, users can make their own judgement as to which projections are most suitable for their purposes.

These projections are not predictions. The projections should be used as an indication of the overall trend, rather than as exact forecasts. The projections are updated every two–three years to maintain their relevance and usefulness, by incorporating new information about demographic trends and developments in methods.

The following results highlight the main trends from these projections.

3 in 4 living in the North Island

The population of the North Island will increase by an average of 0.9 percent a year between 2011 and 2031, from 3.4 million to 4.0 million (medium projection). Almost three-quarters of this growth will be in the Auckland region, which will rise 1.4 percent a year. The remainder of the North Island is projected to grow by an average of 0.5 percent a year during this period. By 2031, the North Island is projected to be home to 78 percent of New Zealand's population, compared with 76 percent in 2011.

The population of the South Island is projected to increase by an average of 0.6 percent a year, from 1.0 million in 2011 to 1.2 million in 2031. The faster projected growth of the North Island mainly reflects its higher rate of natural increase (births minus deaths), resulting from a higher birth rate and lower death rate than the South Island. This is partly due to the slightly younger age structure of the North Island, which has a higher proportion of population at ages under 45 years.

Population growth in all regions

All 16 regional council areas will have more people in 2031 than in 2006, although 17 territorial authority areas will have less (medium projection). Even in regions with growing populations, the growth rate will slow over the projection period, as the population ages and deaths increase relative to births. As a result, by the 2020s there is the prospect of small population declines in Gisborne, Taranaki, West Coast, and Southland regions, as deaths and departures exceed births and arrivals. 

Graph, Population of regional council areas, 2006 and 2031, medium projection.

Map, Regional population change, North Island territorial authority areas, between 2006 and 2031, medium projection.

Map, Regional population change, South Island territorial authority areas, between 2006 and 2031, medium projection.

Auckland's population 2 million in 2031

The Auckland region is projected to account for three-fifths of New Zealand's population growth between 2011 and 2031, with an increase of 500,000 from just under 1.5 million to almost 2.0 million (medium projection). Auckland's population is likely to have surpassed 1.5 million in the year ended June 2012. By 2031, Auckland region would be home to 38 percent of New Zealand's population, compared with 34 percent in 2011.

Natural increase is projected to account for two-thirds of Auckland's growth, and net migration (arrivals less departures) for the remaining one-third. Auckland's overall fertility rate (2.0 births per woman) in 2007–11 is similar to the national average but Auckland has a higher proportion of people in the main childbearing ages (15–44 years). As a result, Auckland has a higher birth rate and lower death rate than other regions.

Net migration does make a significant contribution to Auckland's population growth. New immigrants and New Zealanders returning from overseas add directly to Auckland's population. As most of these migrants are aged 15–39 years, they also go on to contribute births to Auckland's population growth.

Impact of earthquakes on Christchurch's population 

Before the 2010–11 Canterbury earthquakes, Christchurch city's population was growing. In the four-year period ended 30 June 2010, the city's population grew at an annual rate of 1.0 percent, with gains from both natural increase (2,200 per year on average) and net migration (1,600 per year on average). Subnational population estimates indicate that the population decreased by 8,900 (2.4 percent) in the June 2011 year. This decrease was due to a net migration loss of 10,600, partly offset by a natural increase of 1,600.

The projections indicate that Christchurch's population will grow in the future, although the pace and timing of that growth is uncertain. The medium projection indicates average annual growth of 0.6 percent between 2011 and 2031. This assumes net migration of zero in 2012–16, and an average net inflow of 1,300 a year after 2016. These migration assumptions reflect some further relocation of Christchurch residents to neighbouring districts and beyond, notably from red zone areas, but allow for some inflows of workers to assist rebuilding.

More people in most areas

Of New Zealand's 67 territorial authority areas, 50 are projected to have more people in 2031 than in 2006, and 44 are projected to have more people in 2031 than in 2011 (medium projection). The highest projected population growth rates over the 25-year period (2006–31) are for Queenstown-Lakes and Selwyn districts (an average annual increase of 2.2 percent). Waimakariri district (1.6 percent), Auckland (1.5 percent), Tauranga city (1.4 percent), Hamilton city (1.3 percent), and Waikato district (1.1 percent) are the next highest.

Under the medium projection, the largest percentage decreases in population between 2006 and 2031 are projected for the districts of Ruapehu (down an average of 1.2 percent a year), Kawerau (1.1 percent), Wairoa (0.9 percent), Opotiki (0.8 percent), and South Waikato and Rangitikei (0.7 percent). The decreases in these six areas reflect shrinking natural increase and continuing net migration outflows, although these outflows are assumed to be smaller than experienced historically.

Narrowing gap between births and deaths

The slower population growth across New Zealand is driven by the narrowing gap between births and deaths. Nationally, natural increase is projected to decrease from 171,000 during 2007–11 to 130,000 during 2027–31 (medium projection). At the regional level, only Auckland will have more births in 2027–31 than in 2007–11. All 16 regions will experience more deaths.

In 56 of the 67 territorial authority areas, the number of births is expected to drop between the period 2007–11 and the period 2027–31 due to the assumed slightly lower fertility rates (average number of births per woman), combined in many areas with a decline in the number of women in the childbearing ages. In contrast, the number of deaths is expected to increase in all areas, despite continued increases in life expectancy. This is because of the increasing number of people reaching the older ages. About 4 deaths in 5 currently occur at ages 65 years and over.

Deaths exceeding births in more areas

In the five years ended June 2006, five of New Zealand's 67 territorial authority areas experienced more deaths than births: Thames-Coromandel, Horowhenua, Kapiti Coast, Waimate, and Waitaki districts. In 2007–11, following an upturn in fertility rates across the country, births were higher than deaths in almost all areas, and only Thames-Coromandel continued to experience a natural decrease. However, as the general ageing of New Zealand's population continues, other areas will begin to consistently experience natural decrease.

By 2021, an additional four districts are expected to have more deaths than births: Horowhenua, Kapiti Coast, Timaru, and Waitaki. By 2031, they will be joined by another 11 districts: Hauraki, Wanganui, Masterton, Carterton, South Wairarapa, Marlborough, Kaikoura, Buller, Westland, Waimate, and Gore. Deaths will therefore outnumber births in about one-quarter of territorial authority areas by 2031 (medium projection). All these areas have an older-than-average age structure, with relatively high proportions of the population aged 65 years and over.

For areas that have traditionally relied on natural increase for population growth, a natural decrease will mean a shrinking population unless offset by net migration gains. However, a net migration inflow would be a reversal of historical migration patterns for many areas.

Ageing population

The population of all territorial authority areas is expected to be older in future. However, there will be considerable variation between areas, largely because of each area's current population age structure, and different fertility and migration patterns. At the national level, the median age (half the population is younger, and half older, than this age) is projected to increase from 37 years in 2011 to 40 years in 2031. At the subnational level in 2011, the median age ranged from 32 years in Hamilton city to 48 years in Thames-Coromandel district. By 2031, the median age is projected to range from 34 years in Hamilton city to 55 years in Thames-Coromandel district. A median age of 50 years or older is projected for seven other territorial authority areas in 2031: South Wairarapa, Waitaki, Kapiti Coast, Horowhenua, Carterton, Buller, and Marlborough districts.

The oldest median ages are generally in areas experiencing low fertility and/or a net outflow of young adults (aged 15–29 years) and a net inflow of people aged 35–74 years. The youngest median ages are generally in areas experiencing high fertility and/or a net inflow of young adults (such as cities with major tertiary education facilities).

Graph, Proportion of population aged 65 years and over, by territorial authority area, 2006 and 2031, medium projection.

More older people in all areas

Under the low, medium, and high projections, all territorial authority areas are projected to have a higher proportion of older people (aged 65 years and over) in 2031 compared with 2006 and 2011. Under the medium projection, the proportion in 2031 will be highest in Waitaki district (36 percent), followed by Horowhenua, Thames-Coromandel, and South Wairarapa districts (all 35 percent). In contrast, older people are projected to account for 15 percent of the population of Wellington city, and 16 percent of Hamilton city, in 2031. For New Zealand overall, 21 percent of the population is projected to be aged 65 years and over in 2031, up from 12 percent in 2006 and 14 percent in 2012.

Fewer children in most areas

Fifty-one territorial authority areas are projected to have fewer children in 2031 than in 2006, and 50 are projected to have fewer children in 2031 than in 2011 (medium projection). Fewer births will be the main reason for the decreasing number of children, caused by the assumed slight decline in fertility rates and, in nearly all of these areas, fewer women in the childbearing ages.

Of the territorial authority areas projected to have more children in 2031, the largest percentage increases will be in Queenstown-Lakes district (up an average of 1.9 percent a year or 2,300 over 25 years), Selwyn district (1.6 percent or 3,800), and Tauranga city (1.0 percent or 6,300). All three areas will gain children through net migration and an increase in births over the projection period.

Under all projection series, all territorial authority areas are projected to have a lower proportion of children in 2031 compared with 2006. Under the medium projection, the areas with the highest proportion of children in 2031 will be Waitomo district (23 percent), followed by Kawerau and South Waikato districts, and Porirua city (all 22 percent). These areas, all in the North Island, have fertility rates well above the national average. Thames-Coromandel district is projected to have the lowest proportion of children in 2031 at 14 percent – down from 17 percent in 2006 and 16 percent in 2011. For New Zealand overall, 18 percent of the population is projected to be aged under 15 years in 2031, down from 21 percent in 2006 and 20 percent in 2012.

Graph, Proportion of population aged under 15 years, by territorial authority area, 2006 and 2031, medium projection.

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