From John Ray's shorter notes
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February 14, 2018
Townsville is NOT dry because of global warming
Townsville is always pretty dry because of where it is. Why was Townsville founded? It has a negligible natural harbour, can't grow much in the way of crops, has no natural resources and only service industries.
Townsville was founded for one reason and one reason only. There is immediately behind it a gap in the Great Dividing Range and the gap is close to the coast. There are some small hills around the place -- who can miss the pink granite monolith of Castle hill? -- but nothing like the behemoths of the great Dividing Range elsewhere, like Mt. Bartle Frere and Bellenden Ker.
So Townsville was an ideal place to run bullock teams and later a railway from the coast through to some pretty good country inland, including the Charters Towers goldfields and the rich silver, lead and zinc mines of Mt Isa. Both trains and bullock teams are very bad at handling mountains but by starting out at Townsville, severe gradients could be avoided (maxing at 2%).
But the Great Dividing Range is the reason why the East coast strip of Queensland is generally so wet. When trade winds blow inland from the Pacific, they are heavily laden with moisture from ocean evaporation. They hit the mountains of the Great Divide and drop the moisture as rain. So a couple of hours drive to the North of Townsville are two of the highest mountains in the State -- Bartle Frere and Bellenden Ker. And guess what lies in their foothills? The town of Innisfail, one of the wettest places in the world.
So Townsville's reason for existence, a break in the Great Divide there is also the main reason why it is dry. You can't have your cake and eat it too. So the guff below is total nonsense. There's NO "invisible barrier that stops rain". It's the lack of a barrier that stops rain. Townsville will always be dry. It would not exist otherwise.
Townsville pipes in water from Mt Spec and Lake Paluma.
Lake Paluma dam
And Townsville's Ross river has a dam on it which also supplies a lot of water. So, with irrigation, Townville does grow crops and life is comfortable, even without much rain.
TOWNSVILLE could go from being the driest city in North Queensland to the wettest place in the state due to a quirk of global warming, a leading professor says.
Professor Ray Wills spoke to the Bulletin after a recent article which stated geography in Townsville could be to blame for the notorious “dome” — an invisible barrier that stops rain — and instead blames climate change.
Prof Wills is a commentator and adviser on sustainability and technology and responded to comments made by Thomas Hinterdorfer, a forecaster from weather group Higgins Storm Chasing.
Mr Hinterdorfer said the geography of Mount Stuart and other smaller surrounding hills were forming a barrier against rain.
Prof Wills noted Townsville had historically experienced wet periods and argued climate change was the real driver of the long dry period and failed wet seasons.
“Mount Stuart hasn’t changed in height, however the climate has and it is changing as a result of global warming,” he said.
Prof Wills said the phenomenon was linked to atmospheric circulation, temperature and rainfall.
He said Townsville temperatures were up and rainfall was down, especially in summer.
The Bureau of Meteorology’s 2017 Annual Climate Survey showed Townsville was the driest of the coastal cities in North Queensland last year and had 30 per cent less rain than the long-term average.
Townsville received just 791mm in 2017, against the long-term average of 1128mm. It is the fifth consecutive year of below-average rainfall in Townsville. The city’s residents also endured a year of hotter-than-average temperatures. But it might not stay dry for long.
Prof Wills said climate change was moving the “climate belt” — areas with distinct climates — south. “What Townsville could well be experiencing is what would have been a dry area further north that is being pushed southward,” he said.
With places such as Tully to the north of Townsville — where average annual rainfall is more than 4000mm — that could mean a wet future for Townsville.
“That’s a possible scenario,” Prof Wills said, but it could take decades. He also said mountains surrounding Townsville complicated forecasts, as did oceanic currents and atmospheric circulation.
Prof Wills said although some areas could benefit from climate change, overall it should be treated as a concerning phenomenon.
SOURCE
Update: I should perhaps have mentioned above that Townsville also has a facility to pump water from the big Burdekin dam into Townsville's Ross River dam when needed. So there are extensive provisions to allow for Townsville's always very limited rainfall. It was limited long before global warming was heard of.
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