They not only enable shoppers to overspend without being overburdened with heavy and bulky purchases but also enable the imprisonment of small children when doing so.  

This not only keeps them safe but allows other shoppers to enjoy their consumerism free from the annoyance of out of control, badly behaved or poorly supervised kids.

Shopping trolleys come in various sizes, have four wheels, of which usually only three run smoothly.

This can cause some anxiety in shopping aisles and is the major reason for errant or run-away trolleys that cause untold damage in car parks to other vehicles.

Unfortunately, poorly trained, unthinking or unintelligent trolley users are not capable of – or are unwilling to - ethically return trolleys to a trolley station after unloading.

Common practice seems to be to place it in the centre of the nearest vacant parking space.

For me, when this happens, the instantaneous rise in blood pressure drives me to highlight to all how senseless and unthinking this really is.  

I immediately stop my car in the middle of the driveway, get out, collect the trolley and return it to the nearest trolley station.  

It is even more satisfying if offenders are still present.

I then park in the vacant spot, smile and walk away.

Outside their designed purpose, shopping trolleys serve other useful purposes. They are the preferred mode of transport for the meagre possessions of the homeless and they are a convenient vehicle for getting a drunken friend home.

When they become unusable or no longer needed you can just throw them in the river.

Kevin Chamberlain, 

Queanbeyan

Simon Corbell undertook to decarbonise the ACT by achieving a target of 100 per cent renewables by 2020. 

Latest Tourism Research Australia international visitor survey shows ACT, "tourist numbers cracked 200,000 for the first time". 

Chief Minister Andrew Barr looked forward, with enthusiasm, to burgeoning arrival numbers, with initial flights from Singapore scheduled for September 21 (Tourists flock to region in new record, QA, 6 September, p.8).

There is dissonance between those two stated objectives, reminiscent of Newton's Law of Motion. The motion is one which expounds, that for every action there is an equal and opposite reaction. 

While energy generators, homes and land transport have all been implicated in the crime of anthropogenic global warming, air transport by virtue of its powerful lobbying, and virtual invisibility, much of the time, has escaped international regulation. 

Scientists estimate, that on present growth trends, aviation might well consume the total global CO² emissions budget by mid-century!  

Eliminating terrestrial bound sources of emissions will be of little import if aviation, so to speak, fills the void.

Aviation kerosene - combusted and jettisoned - contains 260-plus individual components, consisting of hydrocarbons and particulate matter, contributing to atmospheric contamination. 

To date, no reliable scientific data has yet been gathered as to the potential human and environmental effects of such contamination, especially around airports and direct flight paths. 

However it is incontrovertibly evident that more Canberra traffic would increase hazard, with international flights being additive to existing military transports. 

One can only conjecture if the tourism consultants cost-benefit analysis incorporated consideration of aviation's risks?   

Albert M. White, 

Queanbeyan