All steps necessary and lawful should be taken including a population freeze. How about an additional tax on all premises using air conditioning except for hospitals, schools, nursing homes and food storage. There may be other reasonable exceptions. A whole range of tax disincentives can be put into place, and easily. Those who can pay enjoy the amenity; those who can't like me, suffer through the summer swelter.

Thanks Anthony...

As a grumpy old man who's lived through 56 summers without air-conditioning and intends to go to his grave boasting that he maintained that position to the end, I couldn't agree more!

I'd love to see a 'no aircon without solar' rule - where you could only install an air-conditioner if you simultaneously installed sufficient solar panels to operate it...indeed, maybe you should only be able to have aircon as a closed-loop system with solar (maybe back with some battery capacity) so you simply couldn't power it from the grid...

I'm only half kidding about this concept.

Interesting ideas in theory. But I think they'd have almost zero impact on the wealthy who (arguably) have larger ecological footprints than the poor folks who your 'policies' would impact. I don't think you can have any 'sustainablity' enforcement with our current social model, unless you want to further wedge the gap between haves and have nots.

"As a grumpy old man who's lived through 56 summers without air-conditioning and intends to go to his grave boasting that he maintained that position to the end, I couldn't agree more!"

A possible connection between grumpy and no air-conditioning? Where were these 56 summers spent Felix? Tasmania? I got through a few more summers than you without air-con but last summer I gave in: I'm sure Perth summer heatwaves are getting more extreme, so, to avoid going to an early grave I can now turn off the weather when it turns malevolent.

Don't think of it as a bit of environmentally reckless self-indulgence, but as your personal climate change mitigation strategy.

Social Justice is not a necessary condition of ecological sustainability.

If you cannot envision an ecologically sustainable yet entirely unjust social order, then I would suggest that you are not trying very hard.

These are strong points - is it possible to provide any references to the evidence here?

Ah, which points? I'd say the fishing company bearing the economic risk is self-evident. ITQs limiting catch? Have a look at say the AFMA website, or google the many academic papers available, maybe http://adl.brs.gov.au/data/warehouse/pe_abarebrs99000858/PC12427.pdf is a good place to start.

Bycatch? Maybe this http://www.springerlink.com/content/x8832670t613387r/ or this (directly relevant to small-pelagics) http://www.imas.utas.edu.au/__data/assets/pdf_file/0005/149648/R05_0996_Final-Rep.pdf

But the "sheer volume" is just a function of the quota held. The size of the vessel doesn't change that...

58 canoes catching the same fish volume as the "supertrawler" has the same effect on the biomass. Just much less economically efficient.

Oh Andy if only this were true:

"It is virtually impossible to make such a fish species extinct by overfishing - the economics doesn't allow it."

Depends what you would mean by extinct I suppose - but certainly for commercial considerations - financially extinct. Here's two relatively recent overfishing collapses: Gemfish, Orange Roughy, Cod? More historically - our cod Murray Cod?

Did you you know that the first steam boat fishing trawlers used in Australia were imported for "harvesting" our inland waterways for Murray Cod .

The bottom up economics of coastal fishing looks a lot like the owner driver trucker - in hock up to the eyballs...everything tied up in the gear... diesel!!! .... always on the edge of financial failure and always always on the look-out for the next undiscovered mortgage-breaker.. the next Gemfish. So he'll need a bigger boat.

And we know virtually nothing about the reproductive rates of these fish nor their "social" habits... like all meeting up on some spike in the middle of the Tasman - or living to hit 400 years old or so....not what you'd be thinking of as frisky teenagers sowing wild oats each spring are they?

Hopefully by now some science is involved in holding back the Eureka of a new resources boom on some reef ....but ten years ago the field knowledge of these species, their biology, their resilience ... was dismal and if there were warnings they were disregarded. The fisheries based on these species crashed.

Strip mining fish resources is a rather silly and most short-term thing to do. But that's not what history shows us yet. Like with Atlantic cod - profitable right up the last weeks until a near total population collapse - something about breeding being density-dependent from memory. Who knew?

Too few, too far away and everything just stops.

Hopefully we're getting better at it.

But so far - the "economics " of the industry - left to its own devices - is not historically a safe pair of hands.

Some good points in regard to economic viability of data collection and precautionary principles. Although it is worth noting that there is explicit mention of using conservative estimates of Blim and Bmey in the management framework where these are not thought to be well known.

As for the notion that we can't overfish these small, fast living, migratory species to the point of extinction - that is probably correct ... but ... it is not the same as saying that we can't overfish them to the point where other longer lived species reliant on them will be sorely stressed - or even to the point where they may be functionally replaced through some predator-prey interactions across their life cycle from egg to maturity that we haven't fully mapped. We have a history of being surprised by stuff when we fish close to the limits. Here I'm thinking about the blooms of jelly fish off japan or the blooms of fast growing pelagic squid that have been seen in other parts of the world.

Finally, I wasn't thinking of the lump of labour argument in regard to 58 canoes - I was thinking about the life-style choice and societal benefits of artisinal fisheries. The sorts of benefits that are seldom captured by economic arguments.

Fred, nice to have a thoughtful discussion.

You're talking about possible positive-feedback ecological mechanisms that can cause stock crashes. Very unlikely in this case, because there is a huge negative-feedback mechanism - this mackerel species has other (small pelagic) cousins that are also prey for the mackerel predators (mostly large pelagics, seals). So the predation pressure will differentially shift to their cousins.

Lifestyle choice of 58 artisanal canoes? Maybe. But if they were offered a chance to jump to the trawler and/or a place in the labour-hungry Australian society, would they jump? Usually... which would indicate a lifestyle and/or societal benefit of the trawler. That's not an economic argument, although the economic argument would probably show a similar result.

There's actually an interesting and confounding tension between The Science and conveying the issue to the public.

Your Serious Scientists criticise the likes of Jared Diamond, Carl Sagan and I suppose Saint Attenborough as "populisers" - who communicate a"dumbed-down" science stripped of its complexities and nuances.

Obviously knowing the Science is important - but equally is knowing the audience and how to infect them with enthusiasm.

As for your contention that "scientists are real people too" - I'd want to see the data on that.:)

Careful, Peter! Someone may counter that they'd like to see supporting data that Farmers are real people too!

Yep - we're an odd lot that's fer sure.

But it's important to understand our differences as well as our commonalities. And too often the "bumper sticker" approach adopted by environmentalists really isolates them in communities like mine. Even when folks would probably agree with them after a bit of a chat.

I had a couple of Vegan mates here ... taught yoga. His ute was smothered with "Meat is Murder" stickers and the like. Now this is a cattle town. We have three butchers and no cop. My vegan mates were saying a lot about who they were and what they stood for - but they made no friends, no allies and have now gone back to the city.

A pity really. They could have done some gentle persuading and actually improved the way the locals look at these issues and manage their herds. But it requires facts and information - science if you like - to show how and why it should be done, what the effects are for the cattle, for the farmers, for the economy. And it requires a gentle touch... a soft touch on the tiller.

This place is full of eccentrics and really strange funny folks. Landcare is an underground terrorist cell. I get a lot of laughs and surprises. And yes they're human and real - but not like you sophisticated bookish types... "Bumper sticker" slogans - the preaching politics of the righteous - just switch them off in droves.

We need more than hearts on our sleeves - or stickers on our bumpers. We need to understand the audience and why they think the way the do. Then slowly slowly shift them along as we all learn.

Peter O, you have nailed it! Several of the conversations have been dancing around exactly what you've just said. I may not agree with all of your views, but if you don't slap me in the face with them, I'll at least hear you out. Cheers :)