It’s been a long time since I felt a glimmer of hope about our chances of resisting the headlong rush towards climate chaos.

But last weekend something happened.

It was during a minute’s silence called at the end of the People’s Climate March and rally in London, one of around 2,000 taking place around the world on Sunday.

Such a simple thing – to get 40,000 people to shut up and think about the person or persons they cared about most. Because that is what climate change threatens, the very future of the living beings we care most about.

The silence was extraordinary, the concentration generating its own peculiar energy. It was made even more intense by the knowledge that millions around the globe were gathering as we were, with the same intent. The march in New York drew more than 300,000, in the build up to the UN Climate Summit being held in that city this week.

The focus on the personal made me think about the virtue of narrowing down, of concentrating focus, when tackling a subject as vast, scary and all-enveloping as climate change.

The campaign for divestment from fossil-fuel industries does this most effectively. It is fast gathering momentum, with cities, communities and universities responding to citizen pressure and shedding their investments in dirty energy. Desmond Tutu’s recent intervention, that the tactics against firms that did business with apartheid South Africa must now be applied to fossil fuels, added extra clout and moral authority.

Then, at the beginning of this week, came the announcement that nearly 700 financial institutions controlling $30 billion of assets had now pledged to pull their money out of investments that exacerbate climate change. They include the Rockefeller Brothers Fund.

To compound the optimism, the price of oil has slipped to under $100 a barrel, making it, for the time being at least,  less profitable to exploit the ecologically vulnerable and harder to reach resources, such as those in the tar sands.

Bitter experience has taught environmental activists not to enter global UN climate talks like those taking place this week with hope or expectations. But whatever happens in the meeting rooms, popular revulsion at the antics of fossil-fuel companies is steadily mounting, while the cost of renewable energy is falling.

Such a confluence of conditions seems unusual and I have to confess to an attack of optimism; a reawakening of a hope that humanity might just have the sense to make the big switch to green, clean and renewable energy.

These feelings are real. So I’m wary that the next sentence may sound like no more than marketing. But we do actually have two issues of New Internationalist coming up that will be exploring this kind of territory. In November, Jess Worth will be editing an edition on ‘The End of Oil’ and a few months later, Danny Chivers will be tackling ‘Renewable Energy’. I’ll be reading both with a renewed sense of purpose.