Australia has always been very hot. So hot in fact that only a few deciduous trees ever evolved. True some have been brought from other countries and the trees do grow in the cooler regions of Australia today. However, except for small pockets in the tropics evergreens predominate.
Trees which drop there leaves prefer a fixed unchanging climate. Australia is where the unexpected happens. Like the present where we are having a long hot end to summer and it is unusually wet. Evergreens can adapt and take off when conditions are favorable. When deciduous trees lose there leaves it could rain heavily, but they can no longer absorb the moisture. Conversely, putting out leaves when it dry for months on end is totally ineffective. Hold onto your leaves is the moto. When it rains evergreens are ready to push on to further growth.
Australia has one lonely temperate deciduous tree. And wouldn't you know it, the tree only grows in Tasmania, which gets the icy wind from Antarctica. These winds are always there in winter so the deciduous beech or Fagus ("Nothofagus gunnii") puts on a fabulous autumn leaf display then goes dormant during winter.
ALL EVERGREEN TREES IN AUSTRALIA
Australia is currently in a transition period. The La Niña could continue or it could change to El Niño. There is presently a lot of rain. Oddly there is also a drought inland. If it were an El Niño cycle things would be a lot worse. It seems global warming is making La Niña years very hot.
Australia is now getting hot La Niñas along with very hot El Niños. This is bad for the whole world because all continents are affected by weather in the Pacific Ocean.
Some El Niños reach a critical temperature with dry periods being severe. Global warming means that more of them will go over this critical point. The average of extreme El Niños has been one in twenty years.
Australians fear hot dry periods. This was the reason for Queensland's over-investment in bringing water to Brisbane. Now many say it was money wasted, but in the future this capital outlay could pay for itself. The hot dry weather will return and 40 degree days could go on for weeks.
We are obsessed with the oil crisis. So much so that we fail to see other problems that face us in the near future. For example, what about fresh drinking water. If nothing is done soon, the world will be in crisis. Even countries with cold climates, in Europe, are facing a shortage of potable water because of the high population density. As people become Westernized they consume more water. They change from bathing when they can, to having showers every day.
Production oil also impacts on the availability of water. it takes 2.5 liters of water to produce every liter of oil. Even growing bio fuels puts pressure on water, with a thousand liters of water needed to make a liter of bio fuel. The modern way of life is water "heavy":
Wealthy people use 3,000 liters of water each day to live their lives. More drought in the world is putting prices of everything up. When water gets short it does so locally. Moving water from one place to another in bulk is problematical. In the short term it is possible, but in the longer term it is not. Food production will fall behind what is needed over the next two decades if nothing is done.
The oil crisis and carbon pollution are problems but a shortage of water will hurt most of all.