It is interesting how natural phenomena make such people so sure man is causing it, no proof needed.

The cyclone that struck Cape York, on March 4, 1899 killed more than 300 people. Somewhat worse than Debbie? Cyclones are not a new event.

The Northwest Passage has opened many times, Roald Amundsen traversed it between 1903-05 in a square rigged ship and RCMPV St. Roch, a Royal Canadian Mounted Police schooner, traversed the NWP in both directions in the 1940-45 period.

Margaret, you might do some checking.

Adolf Hoel in his 1922 scientific expedition north of Norway found ice conditions were exceptional. In fact, so little ice had never before been noted. The expedition sailed as far north as 81º 29' in ice-free water, over 200 miles north of the recent limit.

The ice in the Arctic and Antarctic varies naturally!

Of the very few glaciers that are monitored, most have been receding for centuries. Most glaciers are on Antarctica and not monitored.

On Greenland during the Medieval Warm Period, around 1000 years ago, Vikings were growing crops. There is no one doing that now because it is too cold.

The mild warming that we have experienced since the end of the Little Ice Age has been hugely beneficial.

John McKerral, Batemans Bay, NSW

Re the strange climate policy suggestion by John Smith (letters, April 4).

To effectively mitigate climate change impacts there is a need to both rapidly reduce carbon emissions and adopt adaptation measures.

With an average temperature increase forecast of probably over 2 degrees by the middle of the century and possibly 6 degrees by the end of the century under the present global emission control effort all the adaptation measures in the world will fail to prevent a climate change catastrophe.

John Smith's idea of not putting investment into emission reduction measures such as renewables and instead diverting it to dry climate agriculture in northern Australia would frankly hasten the catastrophe.

Australia as one of the highest per capita energy emitters cannot expect the rest of the world, particularly poor countries, to carry the burden of emission control.

Rod Holesgrove, O'Connor

For some reason ABC has tried hard to include "Aboriginal astronomy" in their programming.

They have completely embarrassed themselves and destroyed any notion of this skill in their Stargazing program on April 4.

After listening to Professor Brian Cox and other experts discussing the wonders of the universe and the science that has allowed this, they then deferred to an Aboriginal gentleman who advised that his culture recognised a star formation that looked like an emu and had something to do with water.

A more ridiculous juxtaposition of understanding is unlikely.

Jevon Kinder, Murrumbateman

The visit of Afghanistan's President Ghani is a welcome indication of Australia's bilateral relationship, after Prime Minister Turnbull's visit to Kabul in January.

The withdrawal of ISAF troops did not mean "mission accomplished" there, with a strongly resurgent Taliban in evidence.

However, the increase in our military commitment has not been matched by assistance to Afghanistan's civilians. Australia's help continues to decline, from $131million in 2014-15, to $87.1million in 2015-16 and $82.7million in 2016-17.

Foreign assistance makes up 74 per cent of Afghanistan's public expenditure.

An average Afghan income in 2014 was US$680, or about $13 per week. That aid reduction of $48million makes a difference to the average Afghan and their children.

Our refugee policy does not help them. Australia's aid does: more please.

Peter Graves, Curtin

Well done, Sarah Gill ("Leadership has its obligations", April 3, p.12) for calling out Julie Bishop's seeming legitimation (by not denouncing it) of President Duterte's unleashing of a murderous rampage against (mostly poor) drug addicts and dealers.

The US President has dramatically abandoned US leadership on human rights observance in international relations.

This is a moment Australia can and must show that minimal standards of state behaviour are still important for reasons independent of moods in Washington.

What more important time and issue to demonstrate our independence?

Anthony Reid, New Acton

Another Tasmanian local council is discussing changing the date of Australia Day. This is because a very small minority of the Australian community is very vocal about a change on the basis that January 26 was the day Australia was invaded back in 1788.

It cannot be called an invasion, more a small group of people sent out from England to start a penal colony.

None of them wanted to come here but they had no say.

Invasion infers a plan to deliberately conquer and subdue the inhabitants.

This colony of the first boat people, our first migrants, could not be further from an invasion force. Changing the current date of Australia Day may appease this vocal minority group but will definitely upset other groups.

Local, state and federal governments need to stop being pressured into a change that will affect more in the community than this minority group.

Take it to the people and have a referendum. Maybe a triple referendum. Australia Day date change, Australia becoming a republic and marriage equality.

These are major issues that should be decided by the people, not politicians.

Alan Leitch, Austin's Ferry, Tas.

Michael Costello's "mea culpa" (Letters, April 6) is all very well, but it is still a very real concern that it has taken until early April for ActewAGL to be "smoked out" on this matter.

I can't believe that ActewAGL's record keeping and information system is so bad that it didn't know well before Christmas, more than three months ago, that it had a very serious problem.

Customer Service 101 and Business Crisis Management 101 both assume that organisations should communicate early and openly with customers, taking swift action to fix significant problems.

My suspicion is that the organisation was engaged in backside protection, knowing that customers often feel powerless and have little sanction against it, and hoping it would all just go away or that people would forget.

As an aside I went out last night and read our gas meter and checked the reading against our gas bill to make sure that we weren't being overcharged — such was the impact of all of the letters to the CT.

Actew AGL's billing behaviour is the sort of thing that fuels concerns in the electorate about big business behaviour.

John R. Baker, Griffith

It was so good to read in The Canberra Times (Letters, April 6) ACTew AGL's final admission of guilt over months of complaints with its extortionate gas bills.

The CEO, Mr Costello's underestimate of the mismanagement of his gas company is almost as successful as his over guesstimate of his gas bills.

How does he explain employees who had apparently been instructed to bamboozle customers by directing them from one department to another until they gave up and paid up.

The more stubborn of us were offered extended periods of time to pay and a surprising number were offered hundreds of dollars presumably to keep quiet.

We Canberrans own half this company, we are part-responsible for this scandal, and Messrs Barr and Rattenbury were informed thanks in part to the Canberra Times letters.

But they remained as complicit as Mr Costello in the scandalous obfuscation and hoped that we would all just pay up and go away.

P. K. Beckwith, Bruce

I am one of the 32,500 customers gouged by ActewAGL because it didn't bother to read my meter. I am owed $400 as a result of overcharging, but have had no offer of refund.

Furthermore, the graphs in recent bills are misleading because the right-hand column uses different units from the other columns.

I will be changing to reverse-cycle airconditioning, because it is much cheaper for heating than gas, even with renewable energy, and finding another electricity supplier, since AGL can no longer be trusted.

Dave Kelly, Aranda

It is sad to read of the collapse of yet another building company owing up to $4 million, much of which is unpaid wages and superannuation ("Builder collapses owing $4m", CT April 5, p9).

While it is bad enough the government is still allowing these companies to operate without having sufficient funds put safely aside in an untouchable account to pay all outstanding wages and superannuation, a serious issue for the ACT government is revealed in the article.

It is stated a developer who hired the collapsed builder to carry out civil works on an ACT housing estate "would have to pay millions of dollars for ripping out faulty work" which the developer claims "failed to meet ACT building standards".

Why was the building contractor allowed to carry out the "millions of dollars" of faulty work in the first place without any certification?

Why did the developer not supervise the work he was paying the builder to carry out?

Comments from those involved within the ACT government would be welcomed.

Murray Upton, Belconnen

Canberrans already know what the Chief Minister's vision is. I suggest it's "if it's old, knock it down, if it's green, turn it brown". Another vision? What happened to the "knowledge capital", the "bush capital"? When will real community consultation occur before ratepayers are told by the government what's good for them and how much they will have to pay? As for the desecration of the West Basin and the foreshores of Lake Burley Griffin, hang your head in shame Chief Minister.

Suzanne Vidler, O'Malley

Richard Mulgan examined the tenuous existence of the Office of the Australian Information Commissioner ("The watchdog with three heads", The Public Sector Informant, April 2017).

The office, which contains three statutory appointments, the commissioners for FOI, for information and for privacy, was saved from Tony Abbott's effort to disband it by the Senate.

It also survived his effort to strangle it by drastically reducing its budget allocation.

Mulgan was particularly interested in the government's use of aggregate data, an application of the "whole of government" approach.

He didn't mention the jurisdiction of the tripartite office over the ongoing fiascos following attempts to merge the aggregate data of the ATO and the DHS.

It is a big ask of a beleaguered commission to audit probity of these giant departments.

But somebody has to do it.

The secretaries and ministers thereof are simply stonewalling the issue.

Gary J. Wilson, Macgregor

Years back, we widened scope across the states and territories for pleading insanity in cases involving serious crimes of violence.

We also began giving more prisoners psychiatric drugs that may induce violence.

These factors, along with street drugs with similar liabilities has raised the odds of random violence against the public anywhere, any time, even innocent children.

What if Mon Haron Manis, an ex-psychiatric patient, had survived the Lindt Cafe siege?

We should restrict the insanity plea, not widen it further.

We should also be far more cautious of putting people with a history of violence on psychiatric drugs.

Linda Vij, Mascot, NSW

PLIBERSEK SPOT ON

Thank you for Tanya Plibersek's column (canberratimes.com.au, April 5). Tanya was spot on about a woman's wage having nothing to do with what her husband earns. Is more women in the LNP front bench the answer to women's inequality in Australia? I doubt it given the quality of the women they currently have.

Jan Gulliver, Lyneham

TICKING ALL THE BOXES

Why couldn't the brief for Northbourne redevelopment simply mandate that replacement of demolished public housing be incorporated? Which box would that not tick?

Graham Anderson, Garran

VACANT BLOCK A SOLUTION

The report on Wednesday evening's meeting of the Woden Valley Community Council ("Mawson residents vent", April 6, p1) omitted to mention some people spoke in support of using the vacant block on Shackleton Circuit, Mawson, for public housing. As a long-standing Mawson resident I welcome this; a practical use of an unsightly and poorly tended block of land.

John Myrtle, Mawson

ABETZ MISSING POINT

Tasmanian Senator Eric Abetz's claim gay people can "become" straight misses an important point and highlights his anti-equality bias. He seems to imply most gay people would prefer to be straight.

I doubt that this is the case, any more than suggesting the good senator and his straight friends might prefer to be gay.

Ross Pulbrook, Wyong, NSW

SILENT WITNESS

The USA, UK and Australia went to find weapons of mass destruction in Iraq and found nothing. We see Syria using WMD and we are silent. But why?

Sankar Kumar Chatterjee, Evatt

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