Civil and Human Rights · History · Science

Significant changes in NZ birth statistics

New Zealand’s birth rate has fallen well below replacement level. The average number of births per woman has fallen to 1.6 in 2021, the lowest ever, compared with its 1961 peak of 4.31 (which was in the final quartile of the post-war Baby Boom and was the year the Pill became available in NZ).

A total of 57,105 live births were registered in the year to 31 March 2021, representing a statistically significant fall from the 21st-Century peak of 64,341 births in 2008 and the all-time peak of 65,391 in 1962 (when the population was much lower; 2.42 million compared with 5.12 million now).

Despite continued growth in average life expectancy (around 82 years now, compared with around 63 years a century ago), the “natural increase” in population is now consistently below the death rate; meaning the population can only increase with continued immigration.

Another major change is a sharp fall in the number of teenagers giving birth and an equivalent rise in women over 40 giving birth. In 1980, the teenage birth rate was 38.2 per 1000 teen females. It is now 9.8 per 100. By comparison, the birth rate for women between 40 and 44 is now 13.42

The number of new mothers in their 40s now exceeds those in their teens for the first time. Many teen pregnancies now appear to be planned; as are pregnancies in women over 40. The growth in the latter appears driven by women choosing to start families later in life, and coincides with women having become a majority of those with tertiary education and many women enjoying careers.

The median age of women giving birth has risen from 25.7 years in 1980 to 30.8 in 2020. For Māori women it is 27.3 years, for Pasifika women 27.7 years, for Pākehā 31 years and “Asian” women 32.1 years.

These NZ trends are reflected around much of the world and may be linked to steady growth in the past 50 years in the proportion of women in higher education and the growth of the middle classes. Countries including Japan and many in Europe have sharply falling birth rates. So do formerly high-birth rate counties such as India and especially China, which abandoned its one-child-policy in 2015 from concern at having insufficient young people to support a growing elderly population, with no upward effect on birth rates.

World population is expected to peak at 9.7 billion in 2064 and decline to 8.8 billion by the end of the century.

All this is good news – for the status and position of women in societies; and for the reduction in the pressures on resources that were caused by the population growth of the past two centuries. The growth was caused by the very welcome advance of modern science with its resulting massive increases in health and life expectancy. Demand for resources will fall from mid-century, for the rest of this century and well beyond. Thus will modern science and education also solve the climate question so many people are alarmed by and which the media unthinkingly portray as the next Armageddon.

Statistics NZ data retrieved 9 August 2021
Stuff article 9 August 2021: Changing age of motherhood
The Lancet, 17 October 2020: Population scenarios for 195 countries

News media · Science

¡Hola! Buenos días del Ciclón Hola! Or maybe not.

In recent years, the media has gleefully embraced tropical cyclone categories, telling us, for example, that Cyclone Gita, which reached Tonga on February 12 was “Category 4,” the same intensity claimed for the meandering Cyclone Hola, which the media tell us will wreck New Zealand’s Northland,  Coromandel and East Cape today.

Further, we’re often told, many of these storms are almost as big as the Category 5 Hurricane Harvey, which affected Texas and Louisiana last August (a cyclone, hurricane and typhoon are simply different terms for the same kind of tropical storm, depending where they are).

Until relatively recently, they were simply cyclones, when they were cyclones. Or just storms, when they were just storms.

It’s time to hang on a minute. For a start, Hola is so weak it’s no longer a cyclone by any definition, whatever the media are frantically telling us. It is not now even a particularly big storm, as storms go. MetService, the voice of reason, says it will be a “one-day wonder,” but if you find that at all in a news story, it will be buried at the end.

Most importantly, New Zealand forecasters use a completely different category-system than the US. What we call Category 1 and 2 cyclones are not even Category 1 in the US; their Category 1 is our Category 3. Our Category 4 is their Category 2, and so on. The only similarity is that 5 is the top category in both, and we get to 5 well before the American category does.

We use Australia’s Bureau of Meteorology Scale, which (to the media at least) makes our cyclones appear bigger than the same-digit category used under the American Saffir-Simpson Scale. Look at the chart below  this article, or read more about it on the Bureau of Meteorology Tropical Cyclone FAQ.

And stop worrying. Such storms are not becoming more frequent, anywhere. It is just the media coverage of them becoming noisier and more doom-laden. Harvey was the first major hurricane to make landfall in the US since Katrina and Wilma of 2005 — an 11-year gap — but you would never have learned that from the panic-driven media.

New Zealand has had just two real cyclones in the past half century — Bola in 1989 and Giselle in 1968. Bola mainly affected East Cape north of Gisborne. Giselle was the biggest storm by far  experienced in New Zealand’s continuously recorded history, which goes back to a little before 1800. Giselle  did enormous damage along most of the length of the country and sank the inter-island ferry TEV Wahine with the loss of 52 lives. But the way every tiny storm gets reported now, you’d think they’ve never been worse and that this week’s quite normal storm is always worse than last week’s.  And that is nonsense.

cyclone category scale

Chart: Bureau of Meteorology, Australia.

History · Science

A history of time, space and the wonders of the universe, in 800 words

Expansion and history of the universe

We live at a time when we know many of the secrets and history of the universe, and even where time and the universe are heading. Yet until only a few centuries ago, people looked into the night sky and — if they thought about it at all — had no real idea of what they were seeing, only myths and guesses.

The people of 1618 could look up and see the stars and planets (the latter looked like stars) but (the very few with the just-invented telescope aside) had no idea what they were, beyond being tiny dots of light in the blackness. They could see the moon, often even in daylight, but did not know what it was or what it did. During the day, they could see the sun and feel its heat, and while assuming it was a ball of fire, they did not know actually what it was, despite using it for agriculture, light and warmth.

Even a century ago — when, thanks to great developments in telescopes and science since 1618, we knew the Earth was a big globe that circled a star we called the Sun; that the Earth orbited the Sun and was one of a number of such orbiting planets, many of which had moons that circled them like our own moon; and that our Sun (a huge ball of plasma converting hydrogen into helium by nuclear fusion) was one of millions of stars in a galaxy we knew as the Milky Way — we believed our galaxy was the entire universe.

Today, we know the Milky Way contains billions of stars, many of them with their own orbiting planets, and that the universe contains billions of galaxies. Scientists have estimated the age of the universe at some 13.7 billion years and the age of the Earth as some 4.5 billion years, around the time our solar system formed from matter solidifying into lumps around our newly formed Sun.

We humans have walked upon this Earth for only 200,000 years. Civilisation — the groupings of people into villages, towns and cities and using written languages and rules governing how people interact — has existed for only some 5000 years of that speck of time, and in the beginning not everywhere on Earth, chiefly the Middle East, China, the Mediterranean and likely Zimbabwe and a few parts of what we now call Latin America.

Scientists today believe the universe started with a gigantic cataclysm we now call the Big Bang, a single moment in which time and space came into being. We can posit this—and the age of the universe—from the theories of geniuses like Albert Einstein and Stephen Hawking; by measuring the expansion of the visible galaxies into the void; and by such things as the background radiation believed to be from the Big Bang.

Current physics suggests that all the matter and energy in the entire universe was created in the instant of the Big Bang and was flung into space as plasma that settled, cooled and formed over billions of years into the galaxies, stars and planets, all of it shaped and held together and kept apart by gravity.

Gravity—still regarded as a semi-mysterious force—keeps us standing on the ground rather than floating into space; it keeps the moon orbiting the Earth (while creating the tides as the moon moves above us); the planets circling the sun; and all the stars in the Milky Way and all the other galaxies rotating in huge spirals in space. Spirals that probably have huge black holes in their centres, holes so dense and with gravity so strong that not even light can escape, so we cannot see them.

For some decades, up to the late 1990s, scientists believed the universe would continue expanding, though at a slowly decreasing rate, until gravity forced all the galaxies to fall back towards the centre where it all began, and then everything would collapse in a Big Crunch, leading to a new Big Bang that would start it all again.

But observation of the universe with our latest ocular and radio telescopes suggests the expansion of the universe is actually speeding up, not slowing. This acceleration has been hard to explain by Relativity Theory, so physicists have developed theories about “dark matter” adding to mass and “dark energy” driving the expansion — but so far, we can neither see nor find these strange matters and forces.

Stars have finite lives and though new ones are still being born, all will eventually die. Our sun will consume all its hydrogen in about five billion more years. If the universe keeps expanding to infinity, all the stars will eventually burn out, and nothing will remain — no light, no life, nothing. A dismal prospect.

And yet against all this wonder of the universe, we humans have become so conceited that many of us think we can wave a piece of paper and make the temperature of the Earth rise by exactly 1.5 °C, as if we were King Canute. Wise Canute, though, knew that he could not stop the tides, and proved it. Ironically, his home was Copenhagen.

  •  Image of the expanding universe courtesy NASA Jet Propulsion Laboratory