Geoengineering Appraisals _Bellamy

Next month’s synthesis report from the
Intergovernmental Panel on Climate Change (IPCC)
is due to give the organisation’s verdict on geoengineering, a
radical set of proposals to use large-scale technologies to tackle
climate change.

There are two types of geoengineering. Carbon
geoengineering seeks to remove carbon dioxide from the atmosphere,
for example by capturing it from the air and storing it
underground, or by adding iron to the oceans to trigger
carbon-absorbing algal blooms.

Solar geoengineering is different. It seeks to reflect
some sunlight away from the Earth before it can be trapped by
greenhouse gases.This can be done, for example, by spraying clouds
with sea salt to make them more reflective, or by stratospheric
aerosol injection, where reflective particles are pumped into the


My colleagues and I have been
the importance of ‘opening up’ discussion about
geoengineering to alternative options, different perspectives and
real world complexity.

‘Closing down’ assessment

Our earlier
has shown that the ways in which
researchers frame assessments of geoengineering have important
effects on the conclusions people come to.

It’s common for such assessments to keep
framings narrow. For example, researchers might choose to evaluate
one or more geoengineering techniques, but not consider alternative
options for tackling climate change, like renewable power or
greener lifestyles.

Such narrow framings typically involve also
leaving out public and stakeholder participation, obscuring social
issues under technical criteria, and mishandling uncertainties by
oversimplifying complexity.


Analysis of the frequency of different geoengineering
proposals featured in standard appraisals shows a “closing down”
particular proposals. Source: Bellamy et al., (2012)

Take the
of the UK Royal Society’s
influential 2009 report into geoengineering. It convened a small
group of experts to assess geoengineering proposals against four
technical criteria: effectiveness, affordability, timeliness and

It’s perhaps not surprising then that
stratospheric aerosol injection, an apparently cheap, effective and
fast acting proposal, came out of the assessment as the best
choice. The assessment gave only a token nod to the uncertainties
by adding arbitrary error bars.

We’ve found that this is a common theme. Through
narrow framings, assessments of geoengineering have served to
‘close down’ on certain proposals, with stratospheric aerosol
injection often coming out ahead.


Stratospheric aerosol injection means releasing
small particles into the stratosphere which will reflect incoming
solar radiation, cooling the Earth.

Another way?

This ‘closing down’ in assessments of
geoengineering is a problem, because it risks locking us in to
decisions that are not adequately informed and that will engender
conflict between different values and interests.

Geoengineering is an issue that is too complex
and has too much at stake to be decided by narrow framings that
ignore broader concerns. That’s why we’ve suggested a new way to
perform such assessments, that can help open up discussion about

Developing a technique called Deliberative
Mapping (DM), we have assessed geoengineering proposals alongside
alternative ways of tackling climate change, like low carbon
lifestyles and renewable energy technologies.

We convened a small but diverse international
groups of academic experts, civil society, government and industry
stakeholders, alongside members of the public from Norfolk in the
UK. We asked them to come up with a set of criteria that they felt
were important when assessing different options to deal with
climate change.

The criteria they came up with went beyond
narrow technical criteria to include social issues such as
politics, society and ethics. But they also came up with more
in-depth technical criteria on effectiveness, environmental
impacts, feasibility and economics.

Criteria Map _Geoeng

Criteria for assessing geoengineering proposals
identified by academic experts, civil society, government, industry
stakeholders and the public. Source: Bellamy et al., (

Where in other research, ‘effectiveness’ has
often been simply equated to global temperature reduction, and
‘affordability’ to capital investment, our assessment broadened out
those criteria to account for carbon dioxide reduction and
litigation costs, amongst many other issues.

By expanding the criteria used to judge
geoengineering and by measuring both the optimistic and pessimistic
performance of each option, this method enabled our participants to
consider all of the uncertainties in a much more substantive

A remarkable consistency

You might think that adding more options,
perspectives, criteria and uncertainty into the mix in this way
would make for more disagreement.

But the results of our assessment, published
Public Understanding of Science
Global Environmental Change
, actually reveal
a remarkable degree of consistency.

It became clear that geoengineering proposals
were outperformed by alternative options for tackling climate
change for all of our expert, stakeholder and public

This is a radically different finding to other
assessments that have found geoengineering proposals, in particular
stratospheric aerosol injection, to be preferable. In our study,
aerosol injection actually performed so poorly that it ranked
alongside doing nothing to tackle climate change at all.

This suggests that thinking carefully about how
we make decisions about geoengineering is at least as important as
the decisions we eventually make. I
that continuing to ‘open up’
geoengineering assessment will allow us to find the most robust and
responsible ways of tackling climate change in the

Dr Rob Bellamy is a James Martin Research Fellow
in the Institute for Science, Innovation and Society at the
University of Oxford. Follow him on Twitter @DrRobBellamy