WILL IT EVER RAIN AGAIN?

IS THIS QUEENSLAND DROUGHT THAT CHANGES EVERYTHING?

PHILLIP ADAMS, THE WEEKEND AUSTRALIAN, NOV 23-24 2019: The Gravity Of Water.

HE WRITES, ‘It will take a thousand millimetres to even dent the drought, let alone break it’. I tend to agree with him, invariably. Now you know my politics and philosophy.

A couple of days after reading his article, I had digested the implication of a metre of rain; he’s right, of course. We are unlikely to get a metre, of course. Of course.

On a previous blog under a similar heading I suggested that climate change occurs as a series of steps, not necessarily a gradual slope. I proposed that the tree-cover of any given area may not recover its former health after a prolonged drought, and that many species of vegetation may die out. Seeds sprouting after showers but killed-off in dry soil.

I considered that the the desertification of Australia occurred in this way, from the Centre to the extremities, with tropical and temperate forest retreating after each drought. (By forest I mean trees, not open grassland).

Phillip Adams’ insight: a thousand millimetres of rain, answers a few questions.

Rain after a prolonged Queensland drought does NOT return the situation to normal. Does not replace sub-surface moisture. Rain only instigates a Green Drought. Tree-cover is constantly using deep moisture to survive; the shallow-rooted species (gums, wattles) dry out and die first, but hang on as seedlings, for a while.

When the sub-soil is thoroughly dry, and the deep-rooted species finally die off, they will never return, unless their seeds have Phillip Adams’ metre of rain, in one, long, gentle episode: rain that will penetrate the sub-soil and hold a reservoir to nurture the survival of temperate-forest species.

Hence the drying-out of Australia. A prolonged drought, and there have been many, is not relieved by rain. Neither is it relieved by sudden torrential down-pours, and this is the forecast for the future in Australia, as predicted by the effect of global warming and climate change, and particularly Sudden Stratospheric Warming: fewer and heavier rain-events.

Perhaps the inadvertent but perceptive statement from Adams answers the conundrum of the drying of Australia. In a nutshell, after a prolonged drought, the situation does not return to normal, despite ensuing rain, even good rain. Tree-cover is only maintained by regular rain, dependable rain, whether light or torrential.

Tree-cover is also self-sustaining, to a great extent, barring human interference; artificial destruction (by burning) permanently alters the forest environment, and each fire-event impoverishes both the soil, the species, and the climate.

(For decades I watched the effect of the regular annual burn-offs of Mt Coot-Tha park in Brisbane. The result was a desolation of rotten old trees, no mulch and unviable stunted saplings. A few years of ‘neglect’ enabled straight, healthy sapling to survive with no scars; saplings that would eventually form a healthy forest of shapely trees. Then the burning started again.)

Our climate, long ago, sustained forest coast to coast in Australia, perhaps during the final era of the mega-fauna. The climate no doubt was variable sixty thousand years ago, with floods and droughts, but NOT with fire. Fires were rare and local, and caused only by lightning. Once humanity became widespread in tribes across the continent, and the large grazing species exterminated, and tree-cover regularly and universally burned, the destruction of habitat and consequently of climate, became inevitable.

Fragility is the word. Poke a stick at the environment, and who knows what the result will be. And it’s not just humanity poking the stick: we can’t be to blame for everything…..we haven’t been around that long. It is problematic to blame ourselves for global warming, but very possible. The climate as we think we know it has had many many drastic changes long before humanity existed. The effects of CO2 and its depletion, creation of oxygen, the changes in the Earth’s axis, the movement of the continents, ice ages, asteroid impact: the causes are many that we know of and surely we know little. Burning fossil fuel?

I should be most interested to be able to examine the overall vegetation of Australia during the era of the Megafauna, say 60,000 years ago, or at least before the arrival of humans. There is no doubt that, compared with the present, extensive forest and jungle would cover most, if not all of the continent.

Driving through hundreds, thousands of kilometres of impoverished Queensland landscape, on roads lined with sparse eucalypt and sclerophyl forest, one will often see, in a hillside cleft, a fragment of rain forest dark green against the surrounding grey. A patch of lush green containing no gum trees; hanging on despite the dry. Existing not because of a secret water-supply, but because it is inaccessible to fire. Even on Mt Coot-Tha itself, in the heart of suburban Brisbane, there is a tiny pocket of the original virgin forest surviving in a steep gully, never having been burned: a bright green remnant, a reminder of what Australia was like before Fire.

These tiny remnants once covered the whole country. Their very existence is proof. Even now, a long fire-free period would promote a small expansion of these pockets of tropical forest. This I see happening wherever fire is repressed for a long period, regardless of the rainfall. The dense, shady tropical areas of figs, tall bunias, kauries, hoop pines, vines and deep-rooted species will grow where at present dry bush exists, if, and only if fire is kept away. Those forests of dense shade suppress eucalypts, squeeze them out. Suppress fire too. But the boundaries of rain-forest are vulnerable, and shrink with each burn-off.

Soon the last of the koalas will be burned out of their habitat, either by design or accident. The eucalypts are fire-trees. The dense vine-forest with its clear underwood is resistant, but is reduced in area with every fire encroaching from the bush. The koala will soon be extinct in the wild, despite all conservation, because of inevitable fire; there is no safeguard. Fire is inseparable from humanity; it’s what we do.

There is, then, no doubt whatsoever that the depletion of tropical forest and vine forest, and perhaps thousands of species that depended of those forests, is due solely to deliberately-lit fires. And this for at least 50,000 years. Is this Queensland drought likely to be the worst on record, and is it due to the culmination of centuries of incendiary habits?

The extent of those original pre-human forests is unknown, but may well have covered the entire continent, excepting the grass-land created by the giant herbivores. Dense tree-cover promotes rainfall, soil-conservation, and soil-moisture. Gum-species deplete the whole environment; they are the weeds that survive on the wasteland, contributing nothing, promoting fire.

Here’s a plan, a start, a reparation………Isolate the tropical remnants from fire by gum-clearing and slashing, and those remnants will grow outwards and thrive. Start at the urban centres and work outward. The recent horrific fires are nearly all eucalypt-based. Gum-trees retained in and near housing: crazy. Get rid of them, plant figs, for example; there are hundreds of varieties. Big, shady, undergrowth-killing figs. Within twenty years a park-like garden free of weeds and lantana could surround outlying homes.

So, there’s no doubt in my mind. Science will catch up and prove me right or wrong, but those tiny patches of green in a wasteland of burned landscape show what once existed. How far did the green extend, long, long ago. Perhaps to the Now-Dead Heart of the country…………

Here’s a question. That tiny remnant of original vegetation, surviving in a cleft of rock on Mt Coot-Tha: just how long ago did it extend in every direction, right to The Bay, everywhere? Are there ancient stumps or even roots surviving of pre-fire years, which can be dated? We assume that the landscape of this area has always looked the same, but it has not. The endless tracts of eucalypt-forest are recent; but how recent? 500 years? 5000 years?

Take an area which has never been totally obliterated by regular human-lit fire: the Blackall Range, 100km north of Brisbane in Queensland. It could not be burned-out because the dense tree-cover had no combustible undergrowth sufficient to provide the heat, plus a generally moist humus even during drought. Not obliterated by fire, but by tree-clearing European farmers, exactly dateable, and recent. Now the rainfall has even deserted this once-green oasis: are we surprised? Now the fires have access, finally.

We cannot both clear land and have rainfall-plus-topsoil; an impossible situation.

One metre of rain in one long, gentle event. I can’t see it happening. But I hope. However imagine the complaints; we’d all be praying to our mythical gods for sunshine. More than  a week of rain would turn us all into Poms.