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expert reaction to studies on carbon emissions

Researchers have published three reports across Nature Geoscience and Nature Climate Change on quotas for carbon emissions and limiting climate change.


Professor Myles Allen, Head of the Climate Dynamics Group at the University of Oxford, said:

“It is depressing that the immediate reaction to the news we have a limited carbon pie is discussion of how countries can slice it up. We didn’t save the Ozone layer by rationing deodorant.

“What we will need, to meet any carbon budget dwarfed by vast reserves of highly profitable fossil fuels, is CCS. Countries that claim to take this problem seriously should be requiring their fossil fuel suppliers to sequester a steadily increasing fraction of the fossil carbon they sell to ensure we stick to the two degree carbon budget. This wouldn’t need any international negotiations (which is presumably why the idea is of no interest to international negotiators), but it would solve the climate problem.”


Professor Sybil Seitzinger, Executive Director of the International Geosphere-Biosphere Programme, said:

“Since 2008, China has been the world’s largest emitter of carbon dioxide. It now accounts for 28% of emissions, with the US accounting for 14% and Europe 10%. What is remarkable this year is that China’s per capita emissions outstripped Europe’s for the first time. Moreover, China’s emissions now exceed the US and Europe’s emissions combined. This is an interesting trend and shows the important role China will play in addressing the climate challenge.”


Dr Grant Allen, Atmospheric physicist at the University of Manchester, said:

“These studies go so far in indicating the effects of emissions, but they do not sufficiently take into account the rate of emission of CO2.

“We cannot simply measure cumulative emissions and predict surface temperature as it is emission rate, not total emissions, that govern the concentration of CO2 in the atmosphere.  And that’s important because it is the concentration of CO2 that governs temperature.

“I disagree with the statement in one of the studies that rate is not important and that cumulative emission is directly related to temperature – the physics of that statement are just wrong.  The faster we emit CO2, the greater the warming effect.

“Cumulative emissions are, at best, a blunt tool for policy makers.  Instead the focus should be on reducing the rate at which we pump CO2 into the atmosphere as quickly and efficiently as possible – something I think we can all agree on.”


Dr Miles Seaman, Member of Sustainability Group at the Institution of Chemical Engineers, said:

“The dilemma of matching the dynamics of our increasingly well founded predictions of the effect of climate change and the ability of the institutional structures at both national and international level to respond appropriately are well illustrated by these two positions.

“Of course we know that it will not be easy to establish a workable and equitable basis for restricting carbon emissions on a worldwide basis. There are too many entrenched positions, particularly among the “advanced” nations and national groupings (e.g. the European Commission) to see a way forward which will deliver solutions to operating very low carbon economies. The know-how to do this is well within our grasp inasmuch as knowing that current engineering can deliver these solutions if incentivised to do so.

“But whilst we are on the rack of macroeconomic ‘policy’ which depends on growth unconstrained by resource limitations such solutions will not emerge. However there is some dim light at the end of the tunnel when we see what is happening in the emerging economic powers. From a western point of view, the breathtaking transformations taking place, particularly in China, together with the technological capacity which has brought this about illustrate the likely role that these actors will play in producing a physical dynamic to meet the challenges that have thwarted the current ‘rich’ world.

“If the current political paralysis is not overcome by the obvious need for action, we may find that the game is being played on a much larger field than we currently contemplate.


Professor Dave Reay, Professor of Carbon Management at the University of Edinburgh, said:

“If this were a bank statement it would say our credit is running out.

“We’ve already burned through two-thirds of our global carbon allowance and avoiding dangerous climate change now requires some very difficult choices. Not least of these is how a shrinking global carbon allowance can be shared equitably between more than 7 billion people and where the differences between rich and poor are so immense.

“As governments draft and debate their plans for a post-2020 international climate change agreement, how to avoid this looming ‘carbon crunch’ must be at the top of the agenda.”


Dr Chris Huntingford, of the UK Centre for Ecology and Hydrology, said:

“Climate research findings are often difficult to interpret, even by other researchers. The United Nations do a good job with their reports summarising information on global warming, but even these run to thousands of pages.

“What the authors of these new papers achieve are two very clear statements. First greenhouse gas emissions are still rising, despite many calls for the opposite to happen in order to lessen the risk of unwelcome climatic impacts. Second, if country-based emission quotas are to ever be implemented, then what constitutes an algorithm to achieve this needs significant debate. Should such quotas be based on existing fossil fuel use, country population levels, or some combination?”


Professor Piers Forster, Professor of Climate Change at the University of Leeds, said:

“These studies refine the IPCC numbers and give us roughly 30 years until we emit the trillionth tonne of carbon dioxide and pass the two degrees of warming threshold.

“Warming is currently around 0.8 C since pre-industrial times.  This means that over the next decades the world could be expected to warm by around 0.4 C per decade – twice as fast as anything seen in the historical record.

“Any rebound from the pause in global temperature change would add to this, so the warming rate could be even stronger.  On the other hand, if the world doesn’t warm as we expect, we climate scientists may have serious egg on our face.  I would prefer that to be the case; but I fear the climate scientists may be right.”


‘Persistent growth of CO2 emissions and implications for reaching climate targets’ by P. Friedlingstein et al.,

‘Sharing a quota on cumulative carbon emissions’ by Michael R. Raupach et al., and

‘Cumulative emissions and climate policy’ by David J. Frame et al.

published in Nature Geoscience/Nature Climate Change on Sunday 21 September 2014.


Declared interests

Myles Allen is a co-author of the Frame et al paper.

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