He has been likened to ‘an Old Testament prophet’ by John Carey, identified as the creator of an ‘evil religion’ by biologist John Maynard Smith, and labelled a writer of ‘pop-ecology literature’ by Richard Dawkins. James Lovelock, veteran scientist and author, has been making waves ever since he explained his Gaia theory in a book published in 1979. The atmosphere, he suggested, was not simply created by random events but was made and sustained by the cumulative effects of life on earth; in this sense, the earth is alive.

The hippies adored it; Dawkins didn’t. Thirty years later and just as he turns 90, Lovelock is back and more like the Greek god of thunder, Zeus. His latest book, The Vanishing Face of Gaia: A Final Warning, was published in February and warns of the disastrous effects of climate change which probably won’t explode the earth, but might well doom humanity. Back in 1979, Lovelock’s Gaia hypothesis was ‘for those who like to walk or simply stand and stare, to wonder about the Earth and the life it bears, and to speculate about the consequences of our own presence here.’

The updated version is for those who would just like to be here. He will tell Edinburgh that we should be planning for continents submerged by floods and wasted by drought, a tide of refugees, scarce resources, and slim chances of survival on an irreversibly hotter planet. There’s no more time for standing and staring, Lovelock warns: ‘If we fail to take our planet seriously, we will be like children who take their homes for granted and never doubt that breakfast starts the day … our neglect could soon cause the greatest tragedy in the memory of humankind.’

26 Aug, 6.30pm, £9 (£7).