Acts of non-violent civil disobedience, such as disrupting traffic for 10 minutes in order to draw public attention to issues which are of critical public importance, have a long and proud history, and should be treated with respect and tolerance.

Unbelievably, despite the "Children's Crusade" for climate action, and Extinction Rebellion's protests against the complex and interactive human activities that are driving life on Earth towards extinction, many people still do not seem to get it.

In a very few years now, the people of this planet will be desperately wishing there had been more protest demonstrations while there was still time, more chance for their parents and grandparents to wake up to the extremity of the danger we face, more pressure to force their governments to act to avert, or at least try to ameliorate the catastrophe.

On Thursday, October 17, the 70th anniversary of the official commencement at Adaminaby of the Snowy Mountains Hydro Electric Authority will be celebrated.

The scheme which took 25 years to build was certainly a major engineering achievement for Australia, and at one time was hailed as the "eighth wonder of the world".

However, I believe that the time is well overdue for another major engineering achievement, and that is the formation of an authority to "drought-proof Australia".

I believe that many of your readers can remember the mighty Snowy Scheme, and would agree that a similar organisation should be initiated to combat drought, Australia-wide.

Bill Deane (Letters, October 14) seeks to put to rest any notion of the accuracy of Terra Nullius in its application to the occupation of Australia by Europeans.

He goes on to quote historian Michael Connor when he said in part the "lie" that was Terra Nullius "...tore a wound in the fabric of society which conciliation could never mend..."

I rather fancy that it was the genocide of Aborigines, the dispossession and subsequent mismanagement of land by European settlers that were the real wounds and barriers to reconciliation with our Indigenous people.

But of course we should get the important facts squared away for posterity.

Doug Hodgson (Letters, October 14) we need people with the wisdom and courage of Greta Thunberg; a majority of them voting, and also leading Australia and the world.

We don't want the venal cowards so perfectly depicted recently by cartoonist Wilcox. Unhappy is the land that needs a hero.

It has been reported Gordon Ramsay, ACT Attorney-General, in writing to his federal counterpart concerning the ACT legislation legalising cannabis, said: "this legislation expresses the will of the ACT people".

Just how was this "will of the people" determined? I certainly wasn't consulted to determine my will in this matter (which, by the way, is opposed to the legislation), and I'm not aware of any general consultation on the legislation.

With the Royal Australasian College of Surgeons announcing its rejection of Canberra's legalisation of cannabis, Minister Greg Hunt has appropriately called for details of medical advice behind the legalisation.

In the document Commonwealth Criminal Code (A Guide for Practitioners) issued by the federal Attorney-General's Department the following appears: "It is my hope the new Criminal Code will bring about greater certainty, and in the end, consistency throughout Australia. It is based on the model for national consistency - the Model Criminal Code - which was created for that purpose by the nation's Attorneys-General."

Individual attempts to legalise the drug virtually rule out national consistency within the meaning of the code.

I woke up on Tuesday morning to the ABC news in which the Queen read from what had been written for her.

This included the opening words: "My government's priority has always been to secure the United Kingdom's departure from the European Union on October 31".

These were, no doubt, hard words for her to say. If she had been allowed to vote at the referendum the indications are she would have voted "remain". Though not a royalist personally, I did feel sorry for her.

We were pleased to learn that the kurrajong tree (Brachychiton populneus) is the ideal tree for a hotter Canberra ("Kurrajong tops ideal tree list for a hotter ACT", October 15, p7).

The kurrajong is Civil Liberties Australia's national liberty tree, planted by Jon Stanhope in 2011 at the National Arboretum on World Human Rights Day. You can find it near the kids' playground.

The co-planter was then seven-year-old Charli Withers, born on the day the ACT enacted a Bill of Rights on July 1, 2004, the first Australian jurisdiction to do so.

Civil Liberties Australia selected the kurrajong as an Australian native with an important place in Canberra's history. Capital Hill, where Parliament House stands, was previously known as Kurrajong Hill.

The Morrison government appears to have banned the flight of a climate protest balloon over Parliament House and appears unlikely to back a proposal to declare a climate emergency ("Government sinks balloon at protest", October 15, p2).

This is all consistent with the government's complete disinterest in doing anything meaningful on climate change and even a disgraceful attack by Morrison in the Parliament on October 14 on the UN's global role in climate change mitigation.

As our grandchildren struggle in the future on a warmer, badly damaged planet, the climate denial of the Abbott, Turnbull and Morrison governments will be remembered as the absolute low point of Australian national leadership.

So climate change protesters are making some people a little uncomfortable and causing a little inconvenience.

How terrible. Some people to want to shut them up at all costs even to the extent of vilifying them and imposing harsh penalties for doing what we all should be doing; trying to stop climate change destroying our world.

The reasonable approach to action on climate has been used for years. We have been warned over and over again. It has not been Greta Thunberg who has been telling us of our peril over the years but scientists, experts, well respected organisations, and increasingly, economists and businesses.

Greta has just expressed reasonable and justifiable anger that we have not taken the action necessary to avert a disaster.

Steve Evans ("Have no faith in St Greta's Crusade", Forum, October 12, p31) can only write in a newspaper and lead the life he does because of all the people who went before him who protested about injustice and stupidity, who sacrificed their freedom and even their lives to bring about change. Without them there would still be slavery, discrimination, apartheid, appalling working conditions, child labour and greatly restricted opportunities for women and working class people.

We would not have the vote, the Vietnam War would not have stopped, whales would be extinct and we would still believe the sun goes round the Earth.

Civil disobedience is a justifiable response to the calamity of climate change.

What a screwed-up world we live in. Wonderful human beings die way to young.

Ignorant narcissistic politicians live way too long and forget their duty is to serve us. Ignorant money-grubbers of all persuasions steal the future from our children to sell one more lump of coal.

Donald Trump betrays the Kurds amongst other misdeeds and Melania Trump breaks ground on a new tennis pavilion at the White House. What is going on?

It appears the Kurds are the world's largest ethnic group without a country. Some 35 million live in adjoining parts of Iraq, Turkey, Syria and Iran. They comprise 37 per cent of Iraq's population, 18 per cent of Turkey's, 17 per cent of Syria's and 10 per cent of Iran's. What is wrong with giving them a country consisting of comparable percentages of the areas of those four countries? It would be just.

Errol Good (Letters, October 15) suggests police should have arrested the Extinction Rebellion protesters who obstructed roads and caused inconvenience to those going about their business. He is right of course. However that is what the protesters wanted; to be filmed by an eager media being dragged off to court to be released, probably without even a caution. I feel great empathy with the hapless police .

According to the Coalition government the only customers the "big four" banks should consider are those seeking a housing loan or to amend the terms of their present one. Apparently, anyone else doing business with such a bank is not a customer.

There are many negative views about Trump pulling troops out of Syria. I would imagine the mothers of those troops would not share those views.

When it's left to Barnaby Joyce to defend the rights of Australian citizens such as Julian Assange, specifically vis-a-vis America, you really know radical right cabal extremists are in power in Canberra.

I'm wondering how long before Scott Morrison's irritating smirk starts to wear thin with the Australian electorate.

The proposal by a Victorian councillor to set up a dog poo DNA regime could have provided some interesting challenges. Ie: a compliance officer arrives at the house of the possible culprit with the evidence in a bag. The officer asks what type of dog it is. The owner replies: "He's a little shih-tzu". "I know sir, that's why I'm here!"

Doug Hodgson (Letters, October 14) asks if we want children like Greta voting. A The New York Times editorial referred to her as "...that young lady from Sweden, with her moral intelligence and her capacity to wield the truth like a rapier".

If all 16-year-olds were like Greta I would have to say "yes".

Doug Hodgson (Letters, October 14) I for one do want any Australian 16-year-olds with as much passion and intelligence as Greta Thunberg to be able to vote.

Jeff Bradley (Letters, October 15) does it, or would it, (who the fire victims voted for) have made an iota of difference?

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