Congratulations on your appointment as minister for the environment and energy. The bringing together of these two portfolios for the first time could present a substantial opportunity for sound policy development in Australia.

It must be a considerable relief for you to emerge from the gloom of the resources portfolio, away from the problems of the decline of the fossil fuel sector and the return of the killer black lung disease, into the bright light of nature and our rivers, mountains, forests and reefs. Why, you could even be the minister who saves the Great Barrier Reef – but more of that later.

In the meantime, you may want to have a word with that other new minister, Senator Matthew Canavan, who says he is excited by the prospect of the Adani Carmichael coalmine being built. This result seems unlikely, to say the least, and the comment politically unwise. As you would know, the CEO of Origin Energy, one of our largest energy providers, said recently that he believed no more coal-fired power plants would be built in this country. Along with the prior statement from the CEO of our largest energy company, AGL – that it would abandon coal completely over the next few decades – it seems clear that Australia is entering a new era of clean energy whatever your government’s policy may be.

Yes, you can be the minister who saves the reef, or the minister who kills it.

But this will surely happen with more speed and less disruption if there is a well-planned transition blueprint in place.

However, I hear you say, Adani’s coal is all bound for India via the Great Barrier Reef, so why are the above comments relevant? They’re relevant, minister, because these CEOs aren’t alone in leaving coal behind. The world is moving that way. China is discussing the prohibition of any new coalmines. The United States is closing them at a rapid rate.

More to the point, India doesn’t want our coal. I know you have said that there’s “a strong moral case” to help India, and leaving aside any debate on the obvious sophistry of that position, India’s own energy minister has said, “We want to completely stop the import of thermal coal over the next two to three years.” Quite a short time frame, I think you’ll agree. And this isn’t an old quote. Although Minister Piyush Goyal had made similar comments before, these words were spoken in April 2016.

If construction on the Adani mine started tomorrow, the mine wouldn’t even be producing by this time. So apart from the appalling environmental risks to nature in general, and the Great Barrier Reef in particular, the business case for this mine is unsound. It won’t be funded and it won’t be built. Unwise therefore to spruik it loudly.

It has happened before. Remember the Gunns pulp mill in Tasmania? The then environment minister backed it all the way and even said it would be “world’s best practice”. This was never true, and what was the result? No mill, no company, no jobs – all lost along with shareholders’ funds.

In the Adani situation, you may ask why we should care if Mr Adani loses some money along the way. But, you see, many local contractors are gearing up to supply this mythical mine. They believe Senator Canavan when he says the mine will be built. And don’t forget, Minister Frydenberg, you’ve made similar comments. When local people feel promises have been broken they usually look to break the politicians who made them.

In that regard it may be advisable to temper some of your own comments on the future of coal as an energy source. You are, after all, now the minister for the environment not the minister against it. When you wrote a piece for The Age in 2007 you seemed to hold very different views on the necessity for urgent action on climate change. You said the US was “falling short” on action on the issue, that it was “an important issue” and that it is to be hoped that President George W. Bush will “lead his country ... in tackling climate change” with “the start of an ambitious new agenda of initiatives that seek to reduce carbon dioxide emissions using new technologies and market-based mechanisms”. Well said, sir.

We assume you have the same hopes for our own prime minister’s leadership on climate change and for your contributions to it, but until last week, some of your remarks were very much at odds with those. Of course, people change their views over time, but these seem to come from two separate identities. Hopefully your recent comments mean that there is a third cloak hanging in the closet and you will begin to speak for our rivers, mountains, forests and reefs.

Which takes us back to the Great Barrier Reef. It is under threat, I’m sure you agree with that. Is there any environment minister in the world who would have the temerity to disagree with Sir David Attenborough when he says that climate change is the greatest risk to the reef? As important as water quality and the crown-of-thorns starfish and other issues are, dealing with them doesn’t solve the real threat. Yes, you can be the minister who saves the reef, or the minister who kills it. If it’s to be the former, you’ll have to act quickly and bring your colleagues with you.

Here, too, there are a lot of jobs at risk. Not the 10,000 that your government claims will be employed in building the Carmichael mine (Adani stated fewer than 1500 in a court case), but the 70,000 that state government websites list as relying on tourism generated by the reef.

As an environmentalist I would rather write about nature, but as a businessman it’s easy to recognise this is a significant number of jobs with potential for damaging economic impact. Lots of jobs to be lost. Lots of votes.

Speaking of numbers and votes, I read that both you and Senator Canavan were concerned by the impact that groups such as the Australian Conservation Foundation, of which I am president, and GetUp! and others had in the recent federal election. Your interest is understandable since there are nearly one million active supporters of these organisations. And more to the point, minister, at the ACF we are experiencing exponential growth in supporter numbers. When I joined about a year-and-a-half ago we had 100,000 active supporters. Now the figure is 300,000. Many eyes are upon you.

For the many, some of your comments around the democratic process are confusing. You would have seen the impact in certain sections of your own electorate of people who want real action on climate change, not just numbers or targets. And yet you have made comments that could be taken as a criticism of these people or organisations exercising their right to express themselves in any way they wish.

Again a word to Senator Canavan may be productive. He steps even further into this morass and suggests ways to muffle the voices of these passionate citizens – use the tax act against them or restrict their legal rights.

Surely as an experienced and professional politician you can see the growing body of evidence from here and around the world that when you try to silence the voices of the people, the voices get louder. They shout and roar and burst through any barriers thrown up against them, like a force of nature.

We know you will see that, minister. We rely on you to see it and to act on it.

We remain hopeful. Our thoughts are with you.