Why is Australia so overwhelmingly dry when nearby places like Papua New Guinea, New Zealand, Indonesia, and Tasmania are all so wet and lush?
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Something I haven’t seen mentioned here is that parts of Australia *are* lushly forested. I live in Far North Queensland, closer to PNG than Brisbane, and the whole coast up here is tropical rainforest. We get about 2000mm of rain a year, mainly during our monsoon season (November to May).
Australia gets older a you move West. So the mountains are long gone. Some surface rocks in Western Australia are some of the oldest in the world.
No mountains/lakes means nothing to cause rain
Lol I read this ‘dry’ as in ‘people don’t drink’ and thought wow OP really has zero understanding of Australia.
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Not sure if anyone mentioned this yet but another thing I haven’t heard many people discussing is the high oil content of a lot of Australia’s natural flora, especially Eucalyptus trees.
In California, due to long-term droughts, a lot of old/tall Eucalyptus trees were removed in the recent decade. Eucalyptus are not native there, they are native to Australia, and don’t root well in the California soil. They grow invasively in CA (quickly spread) but without good support (fall over easily, crush things). A lot of us learned these details about how Eucalyptus trees weren’t good for the CA wildlife, ecosystems, etc from this, so to not plant anymore. But more importantly, the leaves and bark of Eucalyptus are very dry already, plus high in oil, and therefore easily flammable. The fallen leaves do not decay very fast, and create a gigantic highly-flammable carpet all around the tree/s. The leaves fall all year, and the oil even hovers in the air as a pungent aroma, which many intentionally inhale for medicinal purposes. California has known for decades the Eucalyptus trees would be bad for the wildfire problems CA already is known for too, so out there you hear about how those specific types of trees should be cut down during droughts.
As you can imagine, large stretches of forest with Eucalyptus or other high-oil trees/shrubs are basically just waiting to explode in flame as soon as temperatures reach that point. And as mentioned above, they are native to Australia.
I don’t think anyone has mentioned that Australia is an incredibly old continent with almost no geological activity. Volcanic action replenishes the soils, turning up and cycling nutrients. But Australia hasn’t had any of this in a very long time. So the soils loose all their nutrition and only very hardy, long lived plants are able to establish and grow. This little vegetation means that when it does rain in the dry areas (yes, the centre of Australia does indeed flood), the water isn’t “held onto” by anything and basically just washes away and gets evaporated.
Country’s like the ones you’ve mentioned, especially NZ experience a lot of volcanic activity, so they rich soils for vegetation. The east coast of Australia is the youngest part of the country and has experienced the most recent volcanic activity, so has the best soils. It’s also the wettest and most lush.
Edit: source – am studying Australian ecology and environmental science
FYI [the average rainfall of Australian cities is as follows](https://abc.net.au/news/2018-04-24/perth-rainfall-higher-than-melbourne-hobart-and-london/9688142):
Darwin — 1729mm
Sydney — 1216mm
Brisbane — 1022mm
Perth — 733mm
Melbourne — 663mm
Canberra — 620mm
Hobart — 614mm
Adelaide — 530mm
By comparison, London’s annual average is 557mm which would put it second last in that list if it were an Australian city.
Tasmania is part of Australia, FYI (I’m sure you know this but the way you phrased the question made it unclear).
Tasmania has recently seen one of the hottest days in recorded history at 40.8C (that’s 105.4F). Like Victoria & New South Wales, Tassie has also been affected by fires, like [this](https://www.theguardian.com/australia-news/video/2019/dec/31/tasmanian-fire-burns-through-the-night-video?CMP=Share_iOSApp_Other) one, not far from the state capital, Hobart.
I think some of the images commonly seen on Reddit depict Tassie as mostly rainforest but rainfall varies dramatically across the island state with Hobart the second driest capital city in Australia (after [Adelaide](https://www.discovertasmania.com.au/about/climate-and-weather) ). Even the rainforest in Tasmania has caught fire & burned [this year](https://firecentre.org.au/the-2019-tasmanian-fires-so-far-what-has-burned-and-where/) including swathes of the Wilderness World Heritage Area; pretty scary stuff imo.
Farming and mining is also responsible for a lot of damage to the Australian environment. Land clearance and intensive farming techniques have damaged the water table and result in more heat being reflected from dry soil rather than absorbed by foliage. Water is also redirected artificially and inefficiently to water crops like cotton and rice that have been introduced inappropriately.
Australians also create more carbon emissions per capita than anywhere else in the world.
There’s a variety of factors
Australia’s geographical position has a lot to do with it. Australia is south of the high-moisture tropical belt that Indonesia and New Guinea are in. It sits under the subtropical high-pressure belt, which prevents the lifting of air required for rain.
Another factor is sheer size. The coastal areas of Australia actually get a lot of rain, but this drains the moisture out of the air so there isn’t any left to get to core of the continent. Where-as New Zealand is much narrower so the clouds get a chance to rain on the whole sub-continent.
The other part of this is mountains, or the lack there of. Australia doesn’t have any significant mountain ranges so there is no geography to force moisture laden air upwards to seed mountains and glaciers with snow. This prevents river systems from forming like we get in North+South America. The Amazon in the South and Prairies in the North only exist because of the climate caused by the mountain ranges to their West.
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