What difference does a day make to climate change?

This morning in New York the UN will sit down to talk about climate change. Again.

Negotiations about how to tackle the problem have been dragging on for more than 20 years. In that time global carbon emissions have headed ever upward.

Secretary General Ban Ki-moon has bravely carved out an entire day from the UN’s General Assembly timetable to devote exclusively to climate change. But what, you might rightly wonder, can one extra day of talking possibly do to change the pace of action on global warming?

It’s very easy, and quite justified, to feel jaded.

Already last night’s strikes on Islamic State (IS) in Syria overshadow the talks. Once again the day-to-day exigencies of running the world will intervene and distract world leaders from a problem that is far larger, far more dangerous, but not as immediate as everything else.

And the problems leaders attending the UN have to overcome are so massive they hardly bear thinking about: how to radically reduce carbon emissions from a fossil-fuelled world economy that is focused solely on rebuilding itself after a recession? How to coerce poorer countries to grow more cleanly than we rich ones did yet expect them to cope with the climate change risks our pollution created? How to feed and clothe and house 9 billion people in the not-too-distant future without cutting down the rest of the world’s forests?

But there is, I think, reason to be hopeful.

Even though Mr Ban’s plan is only for a day of talks, it is one extra day – important room for diplomatic manoeuvre – ahead of next year’s talks in Paris.

And a lot has changed since the last time major climate negotiations took place. The biggest carbon emitter, China, and a fast-growing one, India, are embracing low-carbon energy. Given the size of their respective economies those countries now lead when it comes to renewable energy and the rest of us follow.

Despite the fact that progress at the UN is agonisingly slow, individual nations and cities have made big pledges to reduce their environmental impact: just yesterday the mayor of New York promised an 80 per cent cut in the city’s carbon emissions.

But the biggest reason for optimism might be the fact that more than 300,000 people turned out on the streets of New York at the weekend to call for action on climate change. While it didn’t make the planet any cooler, it sent a clear message to politicians that people are willing to accept change.

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