(except Bolivia) agreed to pursue the aim of limiting global warming to two degrees
above the pre-industrial level (Knopf et al., 2012).
The two-degree target has come to function as an important anchoring device
(Van der Sluijs et al., 1998) or boundary object (Star and Griesemer, 1989) in climate
science-policy analysis and public debate (Hulme, 2012): ‘a socially constructed
entity which is powerful and has endurance both because it has credibility in many
different worlds and because it works to stabilize discourse across the boundaries
of these worlds’ (Leggewie and Messner, 2012b, p130). It is attractive as a target
for international negotiations (albeit a recent and arguably not necessarily particularly
successful one, given failures of global climate agreements); to governments wanting
to claim commitments; and to media and public commentary aiming to raise the
stakes of climate change mitigation. Economic justifications and interests were added
when the Stern review (Stern, 2006) calculated and publicized the economic costs
of going beyond two degrees. But in the particular ways this discourse has settled,
what is excluded?
First, the portrayal of two degrees as a clear green goal overlooks significant
uncertainties and ambiguities in the relationship between global temperature and
the drivers and effects of human-induced climate change Hulme (2012). These
range from uncertainties about the aggregate global effects of greenhouse gases,
aerosols and black carbon, the sensitivity of climate to them, and the interaction
with natural climate variability, to those around how particular energy systems,
land and forest use and other human activities affect greenhouse gas emissions. Thus,
‘as an “output index” the 2 degree safety barrier is compatible with many possible
“input scenarios”’ (Hulme, 2012, p124). Yet it may be precisely such ‘input’
processes and drivers – and the ways they connect with people’s values, lifestyles
and aspirations – that offer more meaningful versions of green in everyday terms,
and can be more easily linked to policies and regulations towards behaviour
change among people, governments and businesses.
Second, setting the safety barrier at two degrees is highly value laden. The
establishment of any particular limit depends on the assumptions incorporated into
models, and crucially, on the meanings, values and experiences likely to be
associated with warming. Thus a two-degree target may be too high for areas of
sub-Saharan Africa set to experience severe droughts, or small island states
vulnerable to flooding from rising sea levels, at lower temperatures. The Association
of Small Island States along with other developing nations has therefore argued for
an upper limit 1.5 degrees of warming. Meanwhile, some people and places could
tolerate, or even gain in productivity, from three or even four degrees of warming.
Not surprisingly, geopolitical tensions have therefore opened up over precisely where
the safety barrier should be placed. As Hulme (2012) points out, in attempting to
avert such tensions politicians and campaigners frequently revert to arguments about
expert ‘sound science’, declaring two degrees to be ‘what the science demands’
(cf. Millstone, this book). Yet most scientists – and indeed the IPCC – admit that
identifying climate policy targets involves value-judgements that are well beyond
the remit of scientific enquiry.
What is green? 29
above the pre-industrial level (Knopf et al., 2012).
The two-degree target has come to function as an important anchoring device
(Van der Sluijs et al., 1998) or boundary object (Star and Griesemer, 1989) in climate
science-policy analysis and public debate (Hulme, 2012): ‘a socially constructed
entity which is powerful and has endurance both because it has credibility in many
different worlds and because it works to stabilize discourse across the boundaries
of these worlds’ (Leggewie and Messner, 2012b, p130). It is attractive as a target
for international negotiations (albeit a recent and arguably not necessarily particularly
successful one, given failures of global climate agreements); to governments wanting
to claim commitments; and to media and public commentary aiming to raise the
stakes of climate change mitigation. Economic justifications and interests were added
when the Stern review (Stern, 2006) calculated and publicized the economic costs
of going beyond two degrees. But in the particular ways this discourse has settled,
what is excluded?
First, the portrayal of two degrees as a clear green goal overlooks significant
uncertainties and ambiguities in the relationship between global temperature and
the drivers and effects of human-induced climate change Hulme (2012). These
range from uncertainties about the aggregate global effects of greenhouse gases,
aerosols and black carbon, the sensitivity of climate to them, and the interaction
with natural climate variability, to those around how particular energy systems,
land and forest use and other human activities affect greenhouse gas emissions. Thus,
‘as an “output index” the 2 degree safety barrier is compatible with many possible
“input scenarios”’ (Hulme, 2012, p124). Yet it may be precisely such ‘input’
processes and drivers – and the ways they connect with people’s values, lifestyles
and aspirations – that offer more meaningful versions of green in everyday terms,
and can be more easily linked to policies and regulations towards behaviour
change among people, governments and businesses.
Second, setting the safety barrier at two degrees is highly value laden. The
establishment of any particular limit depends on the assumptions incorporated into
models, and crucially, on the meanings, values and experiences likely to be
associated with warming. Thus a two-degree target may be too high for areas of
sub-Saharan Africa set to experience severe droughts, or small island states
vulnerable to flooding from rising sea levels, at lower temperatures. The Association
of Small Island States along with other developing nations has therefore argued for
an upper limit 1.5 degrees of warming. Meanwhile, some people and places could
tolerate, or even gain in productivity, from three or even four degrees of warming.
Not surprisingly, geopolitical tensions have therefore opened up over precisely where
the safety barrier should be placed. As Hulme (2012) points out, in attempting to
avert such tensions politicians and campaigners frequently revert to arguments about
expert ‘sound science’, declaring two degrees to be ‘what the science demands’
(cf. Millstone, this book). Yet most scientists – and indeed the IPCC – admit that
identifying climate policy targets involves value-judgements that are well beyond
the remit of scientific enquiry.
What is green? 29