August 3, 2015

expert reaction to impact of negative emissions technology on climate change

Strategies involving negative emissions, or the removal of carbon dioxide from the atmosphere, have been suggested as a way of mitigating the effects of climate change. Publishing in the journal Nature Communications, a team of scientists has concluded that based on their reported estimates, the development of such technologies should be accelerated and be central to climate policy.

Prof. Jon Gibbins, Director of the UK Carbon Capture and Storage Research Centre, said:

“This study (by Gasser et al) confirms that carbon dioxide capture and storage, from large emitters directly and from the air for distributed and intermittent sources, would be an essential part of any global action that limited net cumulative emissions to tolerable levels.  But a long lead time is required to roll out ‘negative emissions’ technologies at gigatonne scale so it is crucially important that negotiators in Paris set up a framework that will encourage their development and deployment in addition to the renewables and energy conservation that can be used to meet more limited climate targets.”

Prof. Stuart Haszeldine, Geologist and Professor of carbon capture and storage, University of Edinburgh, said:

“Today the USA calls to reduce 32% of its own emissions of fossil carbon by 2030.  Gasser and collaborators show that continuing business as usual with carbon emissions is, literally, suicidal for life on earth. There are several cases in the geological past where greenhouse gases have built up rapidly in the atmosphere and ocean. All have resulted in extinctions of the dominant species – just now, that’s us. There are choices to make: reduce or recapture emissions; or consume less fossil fuel. These all rely on carbon capture and storage – so it’s vital that the UK continues to be a leading nation which actually builds these technologies to decrease carbon emissions. This new UK government has recently pulled back on support for many low-carbon renewable technologies. The UK would be moving in the opposite direction to the USA, if it slowed or cancelled carbon capture and storage in the next year, just when the scientific analysis says carbon capture is an essential part of the future.”

Dr Phil Williamson, NERC Science Coordinator, University of East Anglia, said:

“No-one likes bad news, particularly during August holidays. But the new analyses by Thomas Gasser and colleagues are seriously bad news. Just a few years ago, it would have been possible to avert dangerous climate change by a worldwide effort to drastically reduce emissions of greenhouse gases, particularly carbon dioxide. That opportunity now seems to have passed: reducing CO₂ emissions is no longer enough. Instead it is also necessary to remove CO₂ from the atmosphere, as ‘negative emissions’, if global temperature increase is to be kept below 2°C. Or to consider even more drastic climate interventions (geoengineering or climate engineering), that for a wide range of reasons, are currently regarded as unacceptable.

“Last year the Intergovernmental Panel on Climate Change (IPCC) reached a similar conclusion, but the implications were not made clear: instead cautious optimism seemed in order, with future ‘mitigation’ apparently being able to make good the damaging consequences of current actions. Gasser and his co-workers used Earth system models – rather than integrated assessment models – to calculate the magnitude of negative emissions required for different scenarios. They found that current pledges to reduce future CO₂ emissions (by around 1% per year) are insufficient, since there is not the technological know-how to also remove carbon at the scale required. Even if future emissions were reduced at 5% per year, starting from now, substantial ‘negative emissions’ would still be needed. Thus Earth’s future habitability now not only depends on an oxymoron, but it is highly uncertain whether that is achievable at the level needed.

“The study led by Gasser is not the only one to challenge crucial IPCC assumptions and conclusions: recent reviews commissioned by the Department of Energy and Climate Change have questioned the viability of large-scale bioenergy with carbon capture and storage (BECCS, the major mechanism for negative emissions in IPCC models); see http://www.avoid.uk.net/publications. Furthermore, a new paper in Nature Climate Change by Sabine Mathesius and colleagues has shown that removing CO₂ from the atmosphere does not directly counteract the process of ocean acidification.”

‘Negative emissions physically needed to keep global warming below 2°C’ by Gasser et al. published in Nature Communications on Monday 3^rd August 2015. 

Declared interests

Prof. Gibbins: None declared

Prof. Haszeldine: Prof Haszeldine did not take part on the study. He declares no competing interests. Haszeldine’s research is funded by UK and European Research councils, and consortia of hydrocarbon and energy companies, who have no influence over the results. Haszeldine is on unpaid committees of science and technology experts advising  Scottish and UK Government .

Dr Williamson: He is employed by the Natural Environment Research Council (NERC) as a science coordinator hosted at the University of East Anglia.  He has carried out reviews of the feasibility of climate geoengineering for NERC and the Convention on Biological Diversity (CBD), with interests in that topic area limited to those of objective scientific assessment.  The views expressed above do not necessarily reflect those of NERC or the CBD.