By Ann Link and Juliet Oxborrow

Late November saw Guardian journalist Duncan Clark speak to a capacity audience about his book The Burning Question at a public meeting organised by Transition Town Lewes.

The Burning Question explores how the world has any chance of keeping within the critical 2⁰C temperature rise agreed at the 2009 Copenhagen climate talks, given that carbon emissions keep rising exponentially.

In his talk, Duncan explained that burning fossil fuels has so far put 2,000 billion tonnes of CO₂ into the air. To have a 50/50 chance of staying within the two-degree limit, the world can afford to emit only an additional 1,600 billion tonnes of CO₂ (or just 700 billion tonnes for a 75% chance).

Keep it in the ground

The scary news is that is less than half the world’s known fossil fuel reserves – and only a fraction of what’s potentially available if alternative recoverable sources like fracked gas continue to be exploited.

So what’s the solution? The simple answer is to demand that energy companies leave the majority of fossil fuels in the ground. But as Clark admitted, that’s more easily said than done.

For countries with major fuel reserves, entertaining a vast reduction in production feels like economic and political suicide. It’s no coincidence that when faced with the prospect of a rich source of fracked gas in the UK, the coalition government has suddenly gone cool on the green measures it was busily shouting about a few years ago.

And Clark revealed that even using renewable energy sources may not – on its own – have the positive impact we may assume (apart from showing that a low carbon life is possible). By consuming fewer fossil fuels, we simply push down their price, which increases demand for them elsewhere.

What is needed, says Clark, is not only alternatives to fossil fuels, but agreement on an absolute global limit on the total amount of fossil fuel that can now be burned.

Emergency measures

It’s also time to take emergency measures – for example addressing other warming substances, such as methane and soot, which are easier to tackle than fuel reserves. Large-scale carbon capture and storage could also enable fuel-rich countries to phase out fossil fuels more gradually, and could be achieved by adapting existing oil and gas technology.

And if the major energy companies continue to resist being part of the solution, major institutional investors such as pension funds, university endowment funds, charities and churches need to be encouraged to divest their assets away from them – a trend that’s now growing rapidly in the US.

A 2020 peak

The big message from all of this is that – to have any realistic chance of keeping within that budget of 1,600 billion tonnes of CO₂ – emissions would have to peak before 2020 and then start to come down sharply thereafter. And that’s going require all of us to put pressure on our governments to make it happen and bring alternative energy sources on line.

The recent international climate talks held in Warsaw agreed that countries will have until the first quarter of 2015 to publish plans for cutting greenhouse gases from 2020 – in preparation for the critical climate conference in Paris at the end of 2015. We can all play a part in shaping what those plans will say. As Duncan Clark showed in Lewes, our future may depend on it.

Useful links and information

Why can’t we quit fossil fuels?
Alternatives to the big energy suppliers – a comprehensive guide to renewable suppliers
Burning Question – Actions to take