Greenhouse gas removal by recapturing carbon dioxide and albedo modification techniques that reflect sunlight cannot be relied on to reduce climate change impacts within the next decades, concludes an EU-wide analysis.

Targeted interventions in the climate (known as 'geoengineering' or 'climate engineering') are not a substitute for reductions in CO2 emissions and adaptation strategies to the negative consequences of climate change, says an analysis of techniques for climate engineering by a consortium of 14 European Institutions including the UK's Universities of East Anglia; Edinburgh, Exeter and Bristol.

"It is not yet clear whether it is possible to develop and scale-up any proposed climate engineering technique to the extent that it could be implemented to significantly reduce climate change" says Naomi Vaughan at the Tyndall Centre for Climate Change Research at the University of East Anglia.

Though it is imprudent to expect climate engineering techniques to play a significant role in climate policy in the next several decades, it is sensible to continue to investigate climate engineering techniques to understand their potential in the second half of this century and beyond, states the EuTRACE report (European Transdisciplinary Assessment of Climate Engineering), as well as to understand what kinds of effects they would then have on societies and the environment.

"It is very clear that greenhouse gas re-capture is not an easy option to prevent global disruption. If industrial societies continue to emit fossil carbon and clear forests, the future looks like a series of bad choices. Inventing and constructing climate engineering is far too slow, it is not clear who will pay, and there can be negative impacts on many countries, often poorer nations. Who will choose?" says Stuart Haszeldine, Professor of Carbon Capture at the University of Edinburgh.

"It is important to understand the possibilities and problems associated with climate engineering proposals, in order to make decisions on them in a responsible manner. But it would be irresponsible, based on all we know so far, to expect climate engineering to significantly contribute to solving the problem of climate change in the next several decades. We will only be able to limit the effects of climate change if all states commit to drastically reducing their CO2 emissions, at the Climate Summit in Paris and beyond, following through on that commitment in the years thereafter," says Professor Mark Lawrence, project coordinator of EuTRACE and Scientific Director of the IASS Potsdam.

The report provides an overview of the broad range of techniques that have been proposed for climate engineering, and what these can and cannot do. The report then illustrates many of the challenges and concerns associated with climate engineering, focusing especially on three example techniques: bio-energy with carbon capture and storage (BECCS), ocean iron fertilisation (OIF), and stratospheric aerosol injection (SAI). Existing research on climate engineering is limited, mostly based on climate models and small-scale field trials.

This research has not only shown the potentials of greenhouse gas removal and possibly of albedo modification for partially counteracting climate change over the long term, but has also shown that there are many problems and challenges that would be associated with their implementation, not only in terms of costs, technologies and environmental impacts, but also in terms of societal impacts and the development of regulation and governance.

One scientific challenge that generally applies to techniques for both greenhouse gas removal and albedo modification is understanding how their application could result in numerous harmful impacts on ecosystems, many of which are presently uncertain or unknown. Many other scientific and technical challenges are more specific to one of the two broad categories:

Greenhouse gas removal techniques face numerous scientific and technical challenges, including:

  • determining whether the techniques could be scaled up from current prototypes, and what the costs of this might be;
  • determining the constraints imposed by various technique-dependent factors, such as available biomass;
  • developing the very large-scale infrastructures and energy inputs, along with the accompanying financial and legal structures, that most of the proposed techniques would require

Proposals for cooling the Earth's surface by increasing the albedo face extensive scientific and technical challenges. It is unclear whether any of the proposed techniques would ever be technically feasible:

  • very large and costly infrastructures;
  • delivery mechanisms for injection of aerosol particles into the atmosphere
  • a much deeper understanding of the underlying physical processes, such as the microphysics of particles and clouds, as well as how modification of these would affect the climate on a global and regional basis.

Societal context and development of governance and regulation

A major part of the EuTRACE assessment report was to highlight the possible effects of various climate interventions on human security, conflict risks and societal stability. At present, no existing international treaty body is in a position to broadly regulate greenhouse gas removal, albedo modification, or climate engineering in its entirety. The EuTRACE assessment therefore stresses the value of engaging the public into the discussion about climate engineering. It also suggests that EU member states could consider pursuing an agreement on a common position on various techniques or general aspects of climate engineering, especially if such an agreement could be made consistent with the high degree of importance that EU primary law places on environmental protection.

Source: Tyndall Centre for Climate Change Research