Interesting article but I am no sure that option 4 would happen in 5-10 years.

AFAIK climate scientists are forever updating their models to fit the latest data. The problem is that there are so many unknowns, just how much methane will be released from the melting permafrost, how quickly will the Greenland icecap melt etc. And the nature of tipping points is that you get a discontinuity of a trend, making extrapolation very uncertain beyond that tipping point. There are just so many unknowns (at least for a lay person like myself).

With all these uncertain scenarios predicted to take place beyond the 4 and 8 year electoral event horizons it is no surprise that we see so much political inertia, not just here but everywhere in the world. It will indeed take real leadership to take preventitive action. It's is time for a new Noah to put his (or her) hand up.

Or, Scenario 5: None of the above - very likely.

As gusi points out wisely, too many unknowns. Extrapolating with unknown variables can lead to no end of hysterical predictions. On the other hand, someone might just get lucky and get it right, but I think choosing next weeks winning Lotto numbers would be a far easier task. Let's just go for the ride and see what happens along the way.

Frankly, whatever does happen, I doubt that man's puny efforts have caused the situation, nor will they be able to do anything about it. Human's have a far too grandiose opinion of themselves. Earth is a lot bigger than mankind.

The article could have added another couple of scenarios.
SCENARIO 5: The Susan Greenfield/Paul Davies (two of Adelaide's past Thinkers in Residence) Scenario. One in which Homo sapiens takes off to slash-and-burn another planet rather than learn to accomodate to the limits of this one.
An interesting one, coming as it does from two notable physicists; and the demographic expectation of an extra 3 billion people in another 50 years.
With inability to satisfy reasonable needs of the present 6 billion, we had better get the task done by that time.
Rocketing people to another planet at the rate of 50 per second for half a century would do it; Extra flights required to take bulldozers for arranging the foundations of infrastructure enabling migrants to avoid a period of living in caves and eating raw (meat?) in the dark. Does this scenario envisage leaving some behind?
SCENARIO 6(a). The Ronnie Regan or "press-the-button" good-versus-evil Scenario; a variation of "The Lord will Provide". It assumes the world has been so compromised by the baddies that is beyond saving; That the the only proper course is to nuke the planet. While all will be crisped, the goodies will sing "We will gather by the river" (Styx) as they wait for ferryman Charon to carry them joyfully into Heaven.
SCENARIO 6(b). The Lord Will Provide Scenario. This assumes that Homo sapiens is more than just an ephemeral blip on the evolutionary radar screen ("We were meant to be here"). That those who are of the right faith will be looked after; for ever-increasing their numbers, God will reward - even if it is only in the "next world".

Considering the Australian Government's stance in relation to proliferation of potential nuclear problems, and its preference for the ascendancy of disinformation rather than science on environmental matters, some variation of SCENARIO 6 seems to be the target for the powers that be.
The pity of it all is that it is not necessary. Society would have much better prospects from leadership by politicians of honesty, common-sense, and statesmanship - if they existed.

Part One

Regarding the environment it might be said that in this increasing corporatised world us ordinary folk could again be caught up in the old controversy about freedom of choice - which in history as regards Christianity was finally partly solved by one of our most famous Christians as well as one of our greatest Western philosophers, St Thomas Aquinas.

It was Aquinas who accepted precepts of Ancient Greek philosophy introduced to the West by Islamic students. Apparently Aquinas had already decided that Christianity had to be lifted out of the doleful period we now know as the Dark Ages. Thus it came about that Christian faith became tempered with Aristotelian Reason, which not only greatly influenced the Rennaissance with thoughts more of earthly progress besides an afterlife, but which also gave great impetus to science and the Age of Reason followed by the the Age of Enlightenment-then into the exciting but problematic Democratic Age we are living in now - sensible reason, according to sociologists having become replaced once again with the crude animalistic doctrine of the survival of the fittest.

It was Darwin himself who died condemning former compatriots like Herbert Spencer and Walter Bagehot for helping to form what we now know as Darwinian Socialism, which not only gave more impetus to an already rampant colonialism later proven by the British invasion of South Africa and American imperial adventures into the Spanish possessions on both sides of the Pacific, as well as capturing Hawai.

Further, it was the so-called Darwinistic survival of the fittest concept which historians say not only helped begin WW1, but after Versaille, the angry revival of the Germanic Wermacht, giving sanction to Hitler to give command for all the horrendous Nazi Germanic atrocities WW2.

How impressive it was for America and her victorious allies to forgive the German people for following the fanatical Hitler, gifting them with the Marshall Plan, along with Japan. Also ridding the world of Soviet Stalinism placing the US by then in the global academy award status

Scenario 7 – Pandemic. Not to the extent that it wipes out our species, but to the extent of relieving the world of the massive human population pressure, thus allowing us to basically practice business as usual, but at a much-reduced scale…. until populations build up again, by which time we will have at least a little bit more wisdom and will to live sustainably….. maybe. Or maybe we will have to go through several cycles until we collectively get it through our thick heads.

Scenario 8 - Peak oil. As fuel prices rise, the price of just about everything else rises as well. The economics for families and for all sorts of businesses no longer work. Food and basic commodities are unaffordable, or unavailable due to broken supply lines and terminated production lines. Unemployment becomes rife. Alternative fuel sources just completely fail to match either quantity of affordability of petroleum. Oil wars are beefed right up. Australia’s share of imported oil is stolen by the US. Civil strife ensues and all the world’s countries that are dependent on fossil fuels fall apart. Most of the rest of the world also suffers greatly due to halted food imports and other connecting factors.

I think both of these scenarios are more likely than any of the previously mentioned ones.

One thing to remember is how fragile our specialised society is. Most people study or do aprentiships till they are at least 20 years old. Many study much longer. If for some reason that is not possible because youngsters are required to grow food or fight others much knowledge and skills could be lost and we'd end up in a new dark ages.

@Ludwig the Marshall plan wasn't all altruism. Europe was in ruins, food was rationed for years after the war and the soviet union had been very succesful in its industrialisation in the 30's. France and Italy had huge communist parties and Germany could have gone that way too. One of the conditions of the Marshall plan was that communist parties would be banned and the participants set up liberal democracies. While this choice seems like a no brainer today we shouldn't forget that after WWI many democracries had been setup that soon collapsed and by the 30s had been replaced by dictatorships. Immedeately after WWII communism seemed very attractive to many Europeans and the Marshall plan was devised to counter it. We could in fact argue that the EU is an extention of the Marshall plan as new members get vast amounts of aid and have to commit to a western style democarcy. It is a pity the US couldn't have done the same in their own backyard (Caribian and Central America) I am sure the place would be much more democratic and wealthy. Anyway I digress...