The BMJ meeting on climate change keeps reverberating through my mind, and the apocalyptic feel of the meeting was deeply unsettling. Is the end of the world nigh? And what does that mean for those under 40?

People have been predicting “the end of the world” ever since there has been a written historical record, and in my lifetime I have worried about nuclear war and nuclear winter leading to the end of civilization and possibly humanity.

I also heard Paul Ehrlich talk in the 70s predicting mass starvation because of the population explosion. Famously—and referred to in this week’s Economist—Ehrlich made a bet with economist Julian Simon that the price of five metals—copper, chromium, nickel, tin, and tungsten—would increase over the next decade. This was the Malthusians against the Cornucopians, those who believed that “markets would provide.” Simon won easily, encouraging people yet again to dismiss those who see apocalypse coming. But had the debate been taken in 1995 rather than 1980 Ehrlich would have been right—and about many of his other predictions, including rapidly rising food prices.

A month or so ago an American evangelist predicted the end of the world for the second time—and again was wrong, much to the amusement of many. It’s entirely understandable that people no longer hear predictions of the “end of the world.”

So are the apocalyptic predictions of the climate scientists wrong? They are radically different from the predictions of nuclear winter in that we are set on a path that leads inexorably to very serious consequences. We have to change dramatically in order to avoid the consequences. The route from here to disaster, although full of unpredictable detail, is clear. Nuclear winter, in contrast, depended on action not inaction—and, of course, we may still have a nuclear war. Indeed, I find it remarkable that nuclear weapons have been available since 1945 and used only twice in war.

Climate apocalypse will not arrive until late in this century, long after I’ll be dead, but without drastic change it may arrive in the lifetime of those under 40. The point was made at the meeting that neither the right nor the left has an answer to climate change. The right has difficulty in even accepting the idea of climate change and has reluctance to accept restrictions on markets and individuals, while the left is wedded to entitlements that cannot be afforded. It was thus predicted at the meeting that the crucial political division will be between the over 40s, who created the problem with our excessive consumption, and the under 40s who will suffer the consequences.

I think of this prediction as I look at the pictures of the “99%” occupying Wall Street, the indignados in Madrid, those camped on the steps of St Paul’s, and the young protesting in dozens of cities across the globe. Are these the people who will lead the change we need? They are currently about protest—towards austerity, unemployment, bankers, governments, capitalism, and the 1% that have flourished while the 99% have lost, Their protests are not about climate change, and they don’t have clear and rational demands.

But on Friday night I watched a preview of the new play 13 at the Royal National Theatre, and it features a young revolutionary who stands on a box in a London of the future and says passionately “We are told that we can’t change, that the world must be as it is. But we don’t agree. We can change. We can build a different and better world.”

Squirming in my seat, I thought of my blog that was skeptical of our ability to change enough to avoid serious climate change and confessed my own inability to change. But I love the idea that the young can lead us to a better world.

Richard Smith was the editor of the BMJ until 2004 and is director of the United Health Group’s chronic disease initiative.