Tim Flannery’s keynote address to the Melbourne Writers’ Festival on Friday night at the Melbourne Town Hall must have left more than a few punters feeling decidedly blue. The vision he paints of the coming impacts of climate change is at times little short of apocalyptic.

Yet Flannery’s vision is no exaggeration. And given the stakes, there would be something obscene about soft-pedalling his message just to make our Friday evenings a little cosier, our sleep a little easier. And so, as in his book The Weather Makers, Flannery pulled no punches.

But amid all of the talk of melting ice sheets and Arctic pack ice, rising seas, drowning polar bears, fatally confused bird life and monster storms, he seemed to leave scant room for hope. During the Q&A session at the conclusion of his speech, one audience member jokingly remarked that her friends were considering leaping from the balcony.

I’ve followed Tim’s work since the publication of The Future Eaters 12 years ago. A passionate discoverer and documenter of nature and natural history, he’s a great communicator, too. But with such a profoundly disturbing issue as climate change, the difficulty lies in startling people out of their reverie without turning them into despairing balcony jumpers. It is a difficult balance and — eloquent as he was — I don’t know that he struck it on Friday night.

This is not to take away his due. Tim Flannery’s is an important voice of warning that has helped greatly in shoehorning climate change onto the mainstream agenda. This was, after all, the ultimate reason for his appearance at the town hall. Perhaps in the end, it is only his job to deliver the bad news, uniquely placed as he is at the, er, coal face of nature’s continuing decline.

But it’s hard to imagine he would see it that way. And clearly he doesn’t think the situation is hopeless. What would be the point of communicating at all if this were true? Yet despite some welcome discussion of ways forward, it seemed a bit like cursory garnish on the main course of Armageddon. What was lacking was not so much details but a passionate defence of possibility -– the sense that we can choose to unmake at least part of the dark future he described.

It didn’t seem clear that he believed this. And that is probably the scariest thought of all.