Given the self harm the Liberal members of the Coalition government are engaged in, John may well be right. He builds his case with balance on two obvious Shorten weaknesses – such as whether Shorten by personality would be up to the job and Labor's small target approach under his leadership.

But methinks these two shortcomings cry out for more scrutiny, including through the media.

The small target issue particularly raises questions of trust with many examples of Shorten as a populist turncoat.

For Bill negative gearing was once essential, as were penalty rates.

We would not still be embroiled in the same sex marriage debate had Labor not opposed the plebiscite for political purpose.

John Warhurst poses that "Labor will be well funded and have effective allies in the trade unions and GetUP!"

Yes they will and with that would come increasing union influence.

Shorten has already said that if he were PM he would run the country based on his union experience. With respect, I believe this could be a third weakness – particularly when Shorten stood before the nation after the last election declaring that he would be an Opposition leader for "everyone", irrespective of how they voted.

Not so in our so highly charged political scene – mores the pity in the national interest.

Len Goodman, Belconnen

While I appreciate her pointed arguments, Judith Ireland unfortunately continues to perpetuate a semantic myth regarding wedlock in Australia – that it is intrinsically unequal.

As it currently legally stands, due to my age, I am not entitled to receive a pension.

Due to my gender, I am excluded from being operated on in a women's hospital. Due to my genetics, I am unable to be granted an Indigenous education scholarship.

Who is championing my rights to have free access to these?

Similarly, with marriage, particular sexual lifestyle choices preclude a person from nuptial recognition: we have restrictions on the age of consent, the number of spouses, plus prohibition on marrying one's immediate relative and someone of the same gender.

These laws do not enforce inequality, but rightfully recognise that the mathematics of marriage is unique: one man and one woman constitutes a complementary one-flesh covenantal unit, containing the natural ability to reproduce.

Reducing wedlock to simply what gives consenting adults emotional satisfaction, regardless of gender, will strip this sacrosanct institution of its inherent authority and ability, and render the concept meaningless.

The right way forward is to champion another term – besides marriage – for gay unions, which can sufficiently describe their biological and ontological differences.

Peter Waterhouse, Craigieburn

Nancy Pelosi, leader of the Democrats in the US House of Representatives, was recently asked whether the Democrats could stake out a clearer contrast to right-wing economics, after a Harvard University study showed 51 per cent of Americans between the ages of 18 and 29 no longer supported the system of capitalism.

Pelosi was visibly taken aback. "I thank you for your question," she said, "but I'm sorry to say we're capitalists, and that's just the way it is."

Pelosi's response, I think, defines the underlying paralysis of politics in Australia.

Thinking outside the square, and accepting that governments need to deal with changing economic realities, surely a debate about introducing a Bill of Rights, to encompass what Australians expect from government and what government can reasonably provide, is overdue in Australia.

Rights and services come at a cost, so a reality check on personal and corporate taxation contribution levels could be achieved in an environment of compromise.

People understand hardship, provided the system is fair.

No doubt there would be agitated hand wringing from those embedded with the concept of trickle-down economics, but services guaranteed by government would still leave ample scope for the private sector to profit and states to concentrate on state issues. It can't be rocket science, just a will to commit.

What kind of world are we living in when Malcolm Turnbull can receive "The Disraeli Prize" from the British think tank "Policy Exchange" while continuing to detain more than 2000 men, women and children who have lived on Manus Island and Nauru over the years in disgraceful conditions?

They have been subjected to abuse and neglect.

At least eight have lost their lives – either murdered or through medical negligence.

Many have been there for almost the entire four-year period since Prime Minister Rudd announced that no-one arriving by boat to seek asylum in Australia would be permitted to settle here.

Canada and New Zealand have said a number of times that they are willing to take these detainees.

Why has Turnbull not taken up their offers?

What prevents Papua New Guinea from sending Manus Island detainees to New Zealand or Canada but fear of being bullied by the Australian Government?

Dr Anne Cawsey, Hackett

In an obvious slapdown of Tony Abbott failed leader (according to Victorian "Liberal" Jeff Kennett) Malcolm Turnbull, told Britain's think tank the "Policy Exchange" Bob Menzies "went to great pains not to call his new Centre Right party a conservative party".

Probably historically accurate, but little did Menzies know his party would descend into the smug, complacent, conservative rabble Australian voters are confronted with today.

Not that the Liberal Party has ever been so, but many Australians would give their eye teeth for a truly liberal, centrist, people-based political party with a social conscience – preferably one which doesn't give our resources away to multinational companies for a pittance.

Jon Stirzaker, Latham

In 1978 glaciologist John Mercer published a paper in the journal Nature, entitled "West Antarctic ice sheets and CO2 greenhouse effect: A threat of disaster".

At the end of the paper he wrote, "One of the warning signs that a dangerous warming trend is under way in Antarctica will be the breakup of ice shelves on both sides of the Antarctic Peninsula, starting with the northernmost and extending gradually southward."

In 1995 the Larsen A shelf, the most northerly of these, collapsed. In 2002, further south, about 3250 square kilometres broke off from the Larsen B shelf, which has since collapsed. Some time between last Monday and Wednesday, about 5800 square kilometres (more than twice the size of the ACT) broke off Larsen C, even further south.

Ice shelves are floating ice rafts, hundreds of metres thick, that have been pushed out from glaciers. Because they are floating, their breakup does not immediately affect sea level. However the shelves act as brakes on the flow of glaciers behind them. Mercer was concerned that loss of the shelves would lead to a substantial speed up of glacial flow and a rapid rise in sea level.

The Antarctic Peninsula contains relatively little ice. Larsen C holds back only enough to increase average global sea levels by 10 centimetres. But the real danger comes from further south in West Antarctica, where the Ross and Ronne ice shelves hold back enough ice to raise average global sea levels by five metres.

Not good for coastal cities.

Paul Pentony, Hackett

Owen Reid (letters, July 11) is wrong about the climate consensus though right about the theory still being a theory.

Theories are frequently tested, and the longer they survive the more they become accepted as the way things are – consensus.

The basic theory of climate change is that if the energy reaching the Earth from the Sun is balanced by the energy leaving the Earth, the global temperature will be stable. If there is an imbalance, the global temperature and climate will change. Theories such as this are subject to experimental test.

Direct measurement by satellite and of ocean temperature currently show an energy imbalance of +0.6 Watts per square metre, with most of that extra heat going into the oceans.

More than 100 years ago it was known that the air's carbon dioxide could absorb heat.

It was postulated that if the atmosphere increased in its CO2 content, the global temperature would rise. The level of CO2 in the atmosphere has risen by 40 per cent while the global temperature has risen by 1°C.

Theory tested and supported.

The global temperature is rising and no cause other than rising carbon dioxide has been found. No source of the CO2 other than emissions from burning fossil fuels has been found. So far these theories of climate change have not been disproved; every test has only served to strengthen them.

Climate scientists accept – there is a consensus – that the theories surrounding anthropogenic climate change are robust.

We would be stupid not to plan for their continued reliability.

Tony Eggleton, Belconnen

It is now exactly four years since the then Labor government, with Liberal Party support, implemented the policy of mandatory and indefinite off shore detention for asylum seekers arriving in Australia by boat.

Consistent with that policy over 1000 men, women and children who came to Australia over four years ago seeking asylum and our protection continue to be detained on Manus and Nauru Islands.

Australia's treatment of these people represents, alongside policies applied to Aboriginal people, the most shocking example of sustained and deliberate state-sanctioned cruelty and inhumanity in Australia in my lifetime.

Jon Stanhope, Bruce

The conclusion drawn by Peter Martin in his article "It's not the wind, it's the gas" (July 13, p 16) – that gas prices have been almost entirely responsible for the recent dramatic rises in energy costs – would no doubt be met with some scepticism by the more conservative MPs and conservative commentators, who like to blame renewable energy for Australia's energy ills.

However, the data that Peter Martin describes speak eloquently for themselves.

Incompetent and/or careless management of the supply and marketing of LPG and coal-seam gas have been responsible – or almost entirely responsible – for the recent dramatic increases in energy costs.

More investment in renewables can only steady the ship.

Douglas Mackenzie, Deakin

It is with profound sadness that all human rights, democracy and freedom defenders the world over receive the news of the death of Liu Xiaobo, the Nobel Peace Prize winner who had dedicated the last 25 years of his life to a China free of Communist tyranny.

For his activism Xiaobo was sentenced to 11 years imprisonment for sedition. He dies of liver cancer whilst under Chinese State incarceration. He was 61 years old.

I join other pro-democracy activists in saluting Liu Xiaobo for the courage he showed in challenging the Communist one-party state status quo and seeking to free the Chinese people from tyrannical rule.

Rajend Naidu, Glenfield, NSW

So, President Trump is going to introduce restrictions on (cheap) steel imports from which Australia is apparently spared. Interviewed on ABC radio on Monday, Finance Minister Mathias Corman would only say the Prime Minister had lobbied President Trump very successfully, adding, "You don't really expect me to reveal what was said in a private conversation, do you?"

I don't think you could call a conversation negotiating Australia's steel exports with the President of the United States private.

That successful lobbying was done on behalf of all Australians. As one of them, I would like to know what the Prime Minister had to promise in order to achieve this successful outcome.

Anne Willenborg, Royalla, NSW

PUBLIC OWNS GOLF LAND

A point of clarification to the recent article ("Federal Golf Club defects to be heard", July 13, p.2) ).

The Golf Club does not own land, it is a renter. The club has never paid a purchase price for the Garran property, rather the ACT Government leases the club the land for the purposes of playing golf. If the ACT Government waives the charge for changing the lease from a golf to a residential purpose it would be a gift worth many millions of dollars from all Canberrans to golf club members.

Michael Mulvaney, Curtin

MPs AND PRINCIPLES

The Fitzgerald Principles require a bare minimum of ethical behaviour from our politicians and I would not be prepared to vote for a prospective MP who is not willing to adopt those principles.

Yet not a single coalition MP is prepared to commit to them.

It would be instructive to know which of the Fitzgerald principles sits outside of the ethical framework of each and every Coalition MP.

Tony Judge, Woolgoolga, NSW

WHAT SILENT MAJORITY?

Really Claude Wiltshire (letters, July 13), the "silent majority of conservative Australians". By what measure?

David Brown, Canberra

TRUMP PACT WITH DEVIL

If you make a pact with the Devil via email but then fail to fulfil that pact you probably shouldn't be too surprised if the emails are leaked to The New York Times.

Bruce Taggart, Aranda

NEW AUSTRALIANS

Remember when they were "New Australians", not asylum seekers, refugees, economic immigrants or illegals.

Chris Emery, Reid

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