You forgot Scenario 4: Business as Usual. Things go on getting better; populations get richer, healthier and longer-lived; diseases are cured; work goes on getting easier; food becomes more abundant, partly due to the contribution of increased CO2; theological and political alternatives to regulated capitalism become increasingly rare, and more and more self-evidently dysfunctional; and fracking provides the cheap and abundant energy that we need to continue living well, and to extend our standards of living into the developing world until nuclear fission becomes viable.

Oh, and the doom-sayers are exposed, laughed out of all credibility and deported to live in the kind of virgin, resource-free island environment that they've been telling us to aspire to for so long.

You left one minor point out JJ.
Populations keep growing rapidly eating us out of house and home (and planet).

This is 2014 JJ.
Nuclear fission has been viable for a few years now.
Remember?

Oops -- fusion, then. But as for global population, I believe that we're still on track to hit a peak around 2080 and then decline.

"debate about how to best run a global civilisation and how to generate the institutions and other processes necessary to do this"

Fail.

This assumes that civilisations are "run" [by the clever ruling class ordering everyone around of course] and the only question is what particular configuration of coercion is "necessary" to do it.

Peter, that believe system has already been destruct-tested over the last 100 years, and proven wrong both in theory and practice, at enormous cost in human suffering.

Try something new? Try re-thinking what doesn't work? Try finding out why it didn't? Try falsifying your own beliefs? Try learning what theories correctly predicted why yours didn't work, and trying to falsify them?

Assuming that humankind is still here or hasnt destroyed itself by then, it is really impossible to predict what the humanly created world will be like in 30 years time.
Due to the ongoing revolutionary development of micro-electronic technologies (and macro ones too) the humanly created world of 2015 is completely different to what it was 30 years ago in 1980.

Yes in the now-time quantum world in which everyone and everything is now instantaneously interconnected something completely new must emerge and business as usual is not an option. Nor is the option advocated by Jardine, which, although he pretends otherwise is just more of the same (turbo-charged business as usual)

This set of references describe the state of the humanly created world in the "21st century", how we got to here, and what if anything we can do about it.

http://www.dabase.org/not2p1.htm
http://sacredcamelgardens.com/wordpress/reality-humanity
http://www.beezone.com/news.html
http://www.coteda.com/fundamentals/index.html

Ateday,

On population explosion, you may like to read this:
http://www.slate.com/articles/technology/future_tense/2013/01/world_population_may_actually_start_declining_not_exploding.html

And that warming pause seems to be stretching out :)

As for east-coast sea-level rise, are any beaches being washed away yet ? Any of them contracting ?

As for a 'world government', and although I don't support it, it's possible that Scotland will break away from the UK tomorrow, or at least will vote to do so. So much for bringing all governments under one. What megalomaniac would even dream of such a totalitarian prospect ?

Another blow against 'world government': what might happen if, yet again, New Zealand was asked to incorporate into Australia ? Fat chance of that ? Then what about Australia and Indonesia ? Fat chance of that ? Then what about Vietnam and China ? Etc.

How easily the 'good' slides into the 'dreadful'.

Thank god for dissidence, chaos, and human contrariness.

Joe

What I believe will happen is none of the above !
As energy gets more expensive and other resource develop higher costs
everything will be come local. As this happens government operations
will withdraw to smaller areas of concern.
Local government will be the most important authority that concerns
the population.
Food production, transport of food and its retailing will all be done
locally.
No longer will we see very large factories with production on a scale
that makes you wonder who is buying all that product.
If you want a table, you will go to the furniture man in the local
suburb, town or village.
The most important thing that we can do is to keep the railways going.
If we manage that we will be able to continue feeding the cities the
way we do now. If we fail we will have to start removing some houses
parks and AFL fields from the denser suburbs to enable market gardens.

Don't think the internet and telephone will keep on keeping on either !
Maybe simple local networks could be kept going but worldwide undersea
telephony would end quite soon.

Electricity will be the measure of our foresight and ability to assign
priorities. If we let that go, we will be going back to the 18th century.

I think reading James Kunstler's fiction book World Made By Hand
would give you a few ideas. It is in many Australian libraries.