Guest essay by Eric Worrall
According to UNSW academic Dr. Clara Stephens, future extreme rainfall will fail to fill Aussie dams, because the drier ground will absorb too much moisture.
What you might not realise about the flow-on effects of climate change
Fri 14 Aug 2020 10.42 AEST
In the coming years, we are likely to see more extreme weather conditions. We will need new engineering approaches to manage the complex impacts on our water resources, writes Dr Clare Stephens.
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Changing rainfall, evaporation and soil
Climate modelling suggests that, in the coming years, average rainfall will decrease over much of the continent. Simultaneously, extreme rainfall is likely to increase, bringing heavier downpours.
Much of the rainfall over Australia is lost to evaporation. The “thirst” of the atmosphere is measured by its evaporative demand. Since the Millennium Droughtbegan in the 1990s, higher temperatures have driven evaporative demand up by increasing the air’s capacity to hold water vapour.
Decreasing annual rainfall and increasing evaporative demand will tend to result in drier soil. Drier soils are more absorbent, so less rain runs directly into waterways. This means that, even if we get heavier downpours in the future, they won’t necessarily produce the floods we rely on to fill dams. Unfortunately, this flood-reducing tendency won’t apply equally to urban environments (where it might actually be helpful) because we have paved over that absorbent soil in cities.
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Read more: https://www.theguardian.com/westpac-scholars-rethink-tomorrow/2020/aug/14/what-you-might-not-realise-about-the-flow-on-effects-of-climate-change
This echoes Tim Flannery’s famous prediction that Aussie dams would never fill again – shorty before record flood years.
Predicting the end of rain is an old game. In the 1920s American hit music hall song “It aint going to rain no mo'”, full of rude verses which poke fun at alarmism, was a worldwide success – not a bad effort in the age before mass media.
This type of science is just getting more and more common in the “outside” sciences. There are two basic ways to understand the “outside”. 1. get out and live in the outside for an extended period, meaning years and not just days. 2. Talk to people who *do* live outside about their experience. Talk to a *lot* of outside people over a widespread area and that means areas the size of states, be they in AU or in the US.
If this so-called scientist had done either of these she would not have made such a simple mistake.
I can’t even tell from the little we are given what *data* she used to come to her conclusion. As we are finding out more and more “average temperature” is a very poor indicator on which to base any kind of prediction. It is certainly not a predictor of the actual temperature envelope let alone things like rainfall. These kinds of predictions are based solely on the assumption that a rising “average temperature” means a rising maximum temperature when the “average temperature” simply cannot tell you that. Even a 6th grader is taught that simple truth about averages. That means far too many of the so-called “climate scientists” don’t know as much math as a 6th grader – let alone have any extended knowledge about the reality of the “outside”.
Eric,
It’s a blonde thing. You wouldn’t understand.
It wasn’t that long ago that Tim Flannery made a similar prediction and all the major metropolitan capitals build very expensive desalinization plants. Then the rains came, the reservoirs filled and the desal plants sat. And they still sit, just waiting for Tim or Clare to be right. How long will they sit idle waiting for Tim and Clare to be right?
They may be started up sometime in the future, but it probably won’t be due to a change in the hydrologic cycle; more like population demand.
have you seen Lake Meade or Lake Powell lately?
Well, being from Oklahoma, I remember “Lake” Optima.
https://www.swt.usace.army.mil/Locations/Tulsa-District-Lakes/Oklahoma/Optima-Lake/
Lake optima was supposed to be filled by the overflow that fills the Ogallala Aquifer. Farmers tapped the aquifer for irrigation and lowered the water table dramatically – so the lake never filled.
It had nothing to do with Climate Change and everything to do with over-use of underground waters in marginal farmlands.
It does however provide a pretty nice (but expensive) wet land for some birds.
P.S. There are some beautiful gypsum caves up near that area, and therefore bats if the wind turbines haven’t already killed them all.
I would like to see this speculation quantified. How much drier? What type of soils? The rainfall pattern? What she says might be true in some cases but not others. Some soils, like silts and clays, only absorb water very slowly, even when dry. Then too, a downpour (over one inch per hour, say) will run off before much can be absorbed by any but the most sandy soils. As it is what she says is simple minded, like most alarmist junk. (My first career was as a water resources engineer, specializing in what is called seepage and drainage.)
When we built a house out in the county that needed a septic system we found out a lot about seepage rate. The county had a whole bunch of tables which would tell you how long your laterals had to be based on several percolation tests at various locations in the lateral field.
My guess is that this “scientist” has no idea that such a thing exists.
If the air warms up a degree, and so it carries more water (which is the AGW claim to get 2/3rds the warming), then how can the air evaporate more water (since it has to already have the additional moisture)? They are using circular reasoning. If water provides 2/3rds of the additional warming and it’s dry air, then instead of that 1 degree increase you get 1/3 of a degree warming due to CO2.
If the air is carrying more water, then raining should increase in intensity, so there is more water available for evaporation (unless the water all runs off somewhere else). SO a warmer climate should mean more rain, which means the heat transport away from the surface of the Earth intensifies, so the heat is lowered.
I sure am glad they have all these mechanisms perfectly modeled so they can make 100 year predictions. (<– Sarcasm)
Left Australia long time ago to emigrate to Beautiful South America Paraguay and rescinded my Australian citizenship I am so glad I did leave Australia its a complete dump used to be great up to the 1970 until Keating started the destroying process which we are now seeing. In my view Australia has no future whatsoever only as a Chinese Colony and it will probably be better off as the Chinese are more stable people
I’d like to move to Paraguay also…..I hear that all Paraguayans have the innate ability to create the most beautifully long run-on sentences…Is this true ?
Look at this from Weatherzone, … https://www.weatherzone.com.au/news/warragamba-dam-at-capacity/532329
Heavier downpours leading to a drier climate. Right.
Hey, I thought increasing CO2 heats us to the tipping point where runaway water vapor finishes the job on us.
Yet a drier climate! Right.
Absolutely – I have long pondered this anachronism – global warming theory depends on the added forcing from water vapour to reach the predicted levels, so a warmer world has more atmospheric vapour – not less, so drought would be less common. They have not absorbed their simple geography lessons about wet tropics and dry deserts. Why do deserts exist – because of less moisture. Why is there less moisture – because the air is colder and can hold less moisture, or it is in a rain shadow (eg the Atacama). Why are the tropics wet – because on the equator more water is evaporated from the oceans and then falls on the land. Anyone who predicts more droughts from global warming doesnt understand climate systems,
I love predictions like this. Rutherford predicted that atomic energy will be of no practical use to mankind (just before the atom was split!) . The US Patent Office predicted in about the 1890s that there are no more useful inventions (just before there was a flood of new inventions). And we have all experienced the recurrent prediction that the end of the world is nigh.
One interesting thing is that such predictions come just before the opposite happens. Therefore Aus must be in for a wet spell.
(PS, my analysis of many Australian weather stations show no consistent trends – rainfall patterns vary from place to place.