The Best Australian Science Writing 2012 (13 page)

Yet we need only look at the appalling famines in Somalia and neighbouring countries to see what happens when too many people try to scrape a living from the land. The great biologist E.O. Wilson puts it sharply: ‘The raging monster upon the land is population growth. In its presence sustainability is but a fragile theoretical construct. To say, as many do, that the difficulties of nations are not due to people but to poor ideology or land-use management is sophistic.'

It took two million years of human history for humanity to notch up its first billion, in 1800. Yet the next billion took only 127 years, and by 1960, a mere 33 years later, there were three billion. The fastest ever growth rate came in the 1960s, with the fourth billion taking only 14 years.

Despite this explosion, the world population growth rate has slowed dramatically since the early 1970s. To me, this slowing in global population growth is the big story. It is where any hope for a sustainable future lies.

For most of history, our ancestors had many children, yet population grew at a trickle because life tended to be short. Mothers routinely died in childbirth, and infants and young children often didn't make it to adolescence.

The explosion in human population, from one billion at the start of the Industrial Revolution to seven billion barely 200 years later, comes almost entirely from improved survival.

A genuine understanding of hygiene and disease, immunisation programs, sanitation, clean water, antibiotics and massive improvements in agriculture have all contributed to longer lives and better childhood survival.

Whenever mortality plummets like this and birth rates remain high, population growth goes through the roof. Our capacity to breed prolifically should be no surprise. After all, evolution has equipped us to excel at reproduction.

Every person alive today comes from an unbroken line of
successful ancestors – people who managed to have at least one child. Many of the most successful ancestors in history are the people who had large numbers of children.

As a result, the genes we inherited from them tend to be genes that give us the behaviour, physiology and anatomy of successful breeders.

But evolution can also be subtle. Sometimes the best way to become an ancestor is not to go at it like rabbits.

In short, millions of years of evolution have equipped us to be exquisitely sensitive to our circumstances in our decisions about how much to invest in each of our children.

When mortality – especially child mortality – is high, it makes sense to have plenty of kids, because not all of them will survive; even more so when children can gather food or work on the farm.

But when child mortality drops and skills and knowledge become economically more rewarding than manual labour, the best way to ensure each child's success is to invest in caring for them and educating them.

That is precisely what happens when economies industrialise. Families that educate and invest in their children achieve social mobility.

Since the start of the Industrial Revolution, birth rates have plummeted in Europe, North America and Australia as families shifted from having as many children as they could afford to investing as much as they could in a modest brood.

The key to dealing with the challenges of population growth will be to educate and empower women and girls, like little Danica Camacho, the symbolic seven billionth baby, who was born in the Philippines on 31 October 2011.

There is one more important but often-overlooked piece of this puzzle. Until now I have assumed that families operate in harmony – that what is good for the mum is equally good for the dad and for the kids.

But in evolutionary terms, different family members can have disturbingly different agendas.

Every baby a woman has increases her chances of dying in labour and decreases her chances of good long-term health. While a father may be bereft at losing his partner in childbirth, he doesn't lose everything. He can always remarry.

So women often do best, in evolutionary terms, if they have fewer, but high-quality offspring. For men, evolutionary success is more of a numbers game, and men often want more children from their wives and more chances to have extra children from affairs.

So at the heart of the trade-off between offspring quality and quantity is an often subconscious tension between husbands and wives.

The industrial era also brought forth feminism, and every step in the empowerment of women shifted the battle over family planning towards smaller and higher quality families.

Safe contraception and access to abortion give women the means to limit their fertility.

Women's education and employment give them knowledge and power within the home to do so. And when women can earn a good wage, families that limit their fertility enjoy more quality time.

Michelle Goldberg concludes her wonderful book
The Means of Reproduction: Sex, power and the future of the world
by arguing that only when governments take women's needs seriously will we have any chance of avoiding Malthusian misery. That is why, she concludes, ‘There is no force for good as powerful as the liberation of women.'

Saving the planet

Darwin

Balancing act

Adrian Hyland

As policeman Roger Wood heads down the drive, he pauses. Listens. He's struck by the eerie silence of the morning. The glare is blinding, the air a shimmering haze. The land is seared and withering under the sun's relentless heat. There's a strange smell in the bush, vaguely reminiscent of cloudy ammonia. A flock of choughs are huddled together, so exhausted by the heat that they can't be bothered stirring. A pair of wrens – beautiful blue feathers, vicious eyes – dart about, little swoops.

He watches a leaf twist and spin in the morning light. Then another. He follows their zigzagging flight, sees more join them. Falling leaves: there's been an astonishing number of them lately.

He gets out of the car, crouches down, runs a hand through the litter on the ground. Picks up a handful and lets it fall. Leaves, bark, twigs, crumbled branchwood drift away. The leaf litter is a world unto itself. Wattle seeds, gumnuts, parched bones. A dragonfly's glassy wing. Creatures too small to be seen with the naked eye. Dry leaf mould. Layer upon layer of it, 15 or 20 centimetres thick in places. All of it crumbling into the great cycle of death, decomposition and birth that is the forest floor. It's thicker than he's ever known it to be. And the rock-hard earth below it hums with stored heat.

The litter is a frightening sight for anybody who's observed with a knowing eye its steady, remorseless accumulation over recent years. It's more than just debris: at this time of the year it's an accelerant. Might as well be petrol.

As he watches those parched fragments trickle through his outstretched fingers, Wood thinks about the interwoven influences of nature and humanity that have brought the bush to such a state. That simple handful of litter bears testament to years of drought, devastating climate change, an environment, already the most flammable in the world, tormented and stretched to breaking point.

All those falling leaves – what do they mean? The trees are in trouble: they're like a ship on a reef, jettisoning cargo, struggling to survive.

The rainfall in the past year has been the lowest on record: in January 2009 only 0.6mm of rain fell, the driest start to a year Victoria has ever recorded. The water storage is lower than it's ever been: Melbourne's dams started the year at a fearful 34.7 per cent capacity and by now they must be at rock bottom. Groundwater levels, soil moisture, fallen logs and stumps are all severely affected. They're all connected, all indicators of danger: the lower the moisture level in the soil, the more ready the bush is to burn.

The drought reached its nadir in the three brutal days of over 43ºC a week ago. Eleven consecutive days of 30+, conditions not seen in 160 years of white settlement. Temperatures like that cure the land, dry it out, prime it.

And today?

Jesus wept. The worst of all. Scorching heat, negligible humidity: less than 10 per cent predicted. The humidity is important. The lower the moisture in the atmosphere, the closer things are to ignition. The wind already feels like a gale blown up from the bowels of hell. And it will get worse as the day wears on.

* * * * *

The McArthur Forest Fire Danger Index is the scale used to measure the threat of fire in the Australian bush. Developed in the 1960s by legendary fire scientist Alan McArthur, it weaves together variables such as wind, fuel, drought, humidity and temperature to come up with a numerical rating that can be applied to any locality. It uses Black Friday – 13 January 1939 – as a measuring stick: the index on that terrible day, when 71 lives were lost, was set at 100, which scientists believed to be as bad as it could get. A day of Total Fire Ban, when it is a serious offence to light a fire anywhere in the open, is declared if the index reaches 50.

Today the fire danger index is off the scale. It varies according to local conditions, but in the countryside around Roger Wood's home it's in the 180s. The weather has gone mad, and the bush is ready to explode.

* * * * *

Climate has been the driving force behind much of human history. It drove our ancestors in and out of the caves, it propelled the Mongols into Europe, the Vandals into Rome. Its vicissitudes were the reason that empires from the Sumerian to the Egyptian – arguably even the Napoleonic, and the Nazi – rose and fell. It allowed humankind to colonise the New World, twice.

Until very recently, humans were outdoor animals with an awareness of weather in our bones. But although we've lived forever in its icy blasts and scorching heat, our understanding of it is still surprisingly limited. We can send a remote-controlled vehicle to Mars, but our best scientists cannot accurately predict the timing of a change in a local wind that will turn a fire about and kill scores of their fellow citizens.

Why? Because the weather is so damned complicated. Even with their staggering computational capabilities, their satellites and multi-dimensional radar imagery, the experts are giving us, at best, an educated guess. Think for a moment about the phenomenal power needed to shift air masses the size of continents around the globe, or lift enough moisture to deposit millions of tonnes of rain onto the Earth's surface every day.

And the atmosphere – the thin blue film of gas it might appear to be from outer space – has a complexity to match that power. Every parcel of air, from a zephyr to a hurricane, is constantly subjected to a battery of influences that include pressure forces, friction, buoyancy, and the deflection of its motion caused by the Earth's rotation, known as the Coriolis effect.

Weather is driven by nature's need for equilibrium. When air ascends in one place it has to come down somewhere else. Simple. But the ramifications interconnect in bewildering ways that have only become apparent with the rise of modern communications: a drought in eastern Australia, for example, could be counterpointed by heavy rains in the southern states of the US. Low-pressure storms in Darwin will coincide with both a highpressure system in Tahiti that causes dry weather and heavy rain in Central Africa and the Amazon. They are all connected.

The driver for this eternal flux, the source of all this power, is the Sun. The Sun's atmosphere is so hot, at 6000ºC, that atoms there can't hold onto their electrons. At its core, the Sun, powered by a cascade of hydrogen fusion reactions, maintains an unimaginable temperature of around 14 million degrees. This gargantuan nuclear powerhouse delivers some 175 trillion kilowatt hours of energy to Earth every hour, generating in a day as much power as 200 million atomic bombs.

If the planet was as flat as our ancestors believed it to be, the upshot of that would be relatively straightforward and weather would be much more predictable. But because of Earth's shape,
rotation and tilt, the radiation that streams into the atmosphere is distributed unevenly. It is strongest at the equator, which is why that is the planet's torrid zone, but the equator cannot just keep on becoming more torrid. The equilibrium imperative ensures that the energy that comes in at the equator moves towards the poles. The circulation of the atmosphere and of the ocean currents is the means by which this happens.

This constant energy transfer causes both air density and temperature to vary enormously, to be in a continual state of flux, as weather phenomena large and small – from super-cells to raindrops – struggle to achieve a balance. The instinct for equilibrium is responsible for the wrenching convolutions and sheer variety of our planet's climate: for the Roaring Forties and the Doldrums, the crushing droughts and the sheets of lightning and ice.

Ultimately, it is also responsible for the teeming variety of life on Earth: for the sleek-backed birds that slip among the manna gums, the nodding greenhood and spider orchids, the fern-filled gullies of the kind that weave their way through the Kinglake Ranges. They are manifestations, all, of climate. And so are the fires that arise time after time and render those varied colours down to a uniform coal black.