Last week the scientists behind two recent publications on carbon emissions urged negotiators at the Bonn climate talks to make phasing out CO2 emissions altogether part of any future strategy.
Myles Allen and David Frame of Oxford University were amongst those who took the unusual step of writing an open letter to policy-makers.
In the letter the team ask those devising targets to take into account their research which shows an upper limit of one trillion tonnes of carbon. If cumulative carbon emissions exceed this limit the world is likely to suffer dangerous global warming of 2 degrees Celsius.
‘In addition to setting targets for emissions in 2020 and 2050, we feel the UNFCCC process should acknowledge that avoiding dangerous climate change will require emissions of the longest-lived greenhouse gases like carbon dioxide eventually to cease altogether,’ Myles Allen of Oxford’s Department of Physics commented.
In the open letter the scientists warn: 'fossil carbon reserves substantially exceed the amount that can safely be released into the atmosphere. Net global carbon dioxide emissions will eventually have to decline towards zero leaving a substantial fraction of available fossil carbon stored, in some form, out of the atmosphere indefinitely.'
'We urge the participants in December's Conference of the Parties to the United Nations Framework Convention on Climate Change to acknowledge the need to limit cumulative carbon dioxide emissions as one element of their vision for long-term cooperative action to avoid dangerous climate change.'
It's probably not something that governments around the world want to hear as they struggle to meet their modest emissions reductions commitments whilst trying to drag their economies out of recession.
Yet what the latest science is telling us is that, as Myles puts it, 'climate policy needs an exit strategy': in other words we need to imagine an end to emissions - a lower carbon economy doesn't actually solve the problem that the atmosphere is a finite resource which will, if we carry on emitting, run out of spare capacity.
It's perhaps a wake-up call to those who think that simply modifying our energy habits will get us out of our current predicament: we need to lower emissions now but we also need to plan an escape route to a zero carbon future.
Dr Myles Allen is based at the Department of Physics whilst Dr David Frame is Deputy Director of the Oxford University Smith School of Enterprise and the Environment