Third, the two-degree discourse defines ‘green’ in singular, climate-related terms.
When applied to particular economies, societies or ecosystems, this can channel
priority to climate over other possible green goals, with problematic consequences.
For instance, large-scale investment in biofuels has been embraced by policy-makers
as a means to reduce fossil-fuel dependence and contribute to meeting climate
targets. Yet as many examples in African, Asian and Latin American settings show,
tensions, trade-offs and conflicts have arisen where land use to grow biofuel
feedstocks competes with food production or uses for local livelihoods (Borras
et al., 2010). The latter may also be ‘green’, but defined in relation to alternative
meanings, whether around sustainable national food security and food sovereignty,
livelihoods, or community ways of life and rights.
Finally, a fixation on global climate targets – and the particular forms of
scientific and modelling knowledge they rest on – can marginalize alternative
meanings, values and forms of knowledge around climate-related phenomena. Social
and cultural analyses, and attention to everyday and citizen expertise and experience,
show how widely varying these are. Climate and weather may be understood and
discussed in terms of practical struggles to ‘get by’ in uncertain, dynamic coastal,
dryland, forest or Arctic settings, or to religious and moral codes, with weather
events and the state of the climate in many societies interpreted as indicative of
the good, or otherwise, state of social behaviour (e.g. Crate and Nuttall, 2009).
In the light of such critiques, some analysts suggest rejecting the two- degree
safety barrier altogether, along with related, single global targets for climate change
(Hulme, 2012). Others argue that it has value as an aspiration, until such time as
more robust scientific and policy approaches ‘improve’ on it (Edenhofer et al., 2012).
Rather than assess this particular green limit as a fixed end, though, it might be
more appropriately treated as a means: appreciating its social contestation, the twodegree safety barrier might be reconsidered as a discursive concept to open up debates
about legitimacy, values and uncertainty, thus creating space for and facilitating
‘democratic discussion about what sort of world we want to live in’ (Shaw, 2010).
Planetary boundaries
‘Planetary boundaries’ offers a more recent and also more all-encompassing
‘green limits’ discourse. From the mid-2000s, scientists started to propose that we
have entered a new epoch, the Anthropocene, in which human activities have
become the dominant driver of many earth system processes including climate,
bio-geochemical cycles, ecosystems and biodiversity. The extent of human
influence has grown rapidly since the Industrial Revolution, accelerating dramatic -
ally since the 1950s (Steffen et al., 2004, 2007). A series of nine planetary boundaries
has been identified, referring to the biophysical processes in the Earth’s system on
which human life depends (Rockström et al., 2009). Together, these serve to keep
the planet within Holocene-like conditions and thus define a ‘safe operating
space’ for humanity. Human actions, it is claimed, are rapidly approaching (in the
case of climate change) or have already transgressed (in the case of biodiversity and
30 Melissa Leach
When applied to particular economies, societies or ecosystems, this can channel
priority to climate over other possible green goals, with problematic consequences.
For instance, large-scale investment in biofuels has been embraced by policy-makers
as a means to reduce fossil-fuel dependence and contribute to meeting climate
targets. Yet as many examples in African, Asian and Latin American settings show,
tensions, trade-offs and conflicts have arisen where land use to grow biofuel
feedstocks competes with food production or uses for local livelihoods (Borras
et al., 2010). The latter may also be ‘green’, but defined in relation to alternative
meanings, whether around sustainable national food security and food sovereignty,
livelihoods, or community ways of life and rights.
Finally, a fixation on global climate targets – and the particular forms of
scientific and modelling knowledge they rest on – can marginalize alternative
meanings, values and forms of knowledge around climate-related phenomena. Social
and cultural analyses, and attention to everyday and citizen expertise and experience,
show how widely varying these are. Climate and weather may be understood and
discussed in terms of practical struggles to ‘get by’ in uncertain, dynamic coastal,
dryland, forest or Arctic settings, or to religious and moral codes, with weather
events and the state of the climate in many societies interpreted as indicative of
the good, or otherwise, state of social behaviour (e.g. Crate and Nuttall, 2009).
In the light of such critiques, some analysts suggest rejecting the two- degree
safety barrier altogether, along with related, single global targets for climate change
(Hulme, 2012). Others argue that it has value as an aspiration, until such time as
more robust scientific and policy approaches ‘improve’ on it (Edenhofer et al., 2012).
Rather than assess this particular green limit as a fixed end, though, it might be
more appropriately treated as a means: appreciating its social contestation, the twodegree safety barrier might be reconsidered as a discursive concept to open up debates
about legitimacy, values and uncertainty, thus creating space for and facilitating
‘democratic discussion about what sort of world we want to live in’ (Shaw, 2010).
Planetary boundaries
‘Planetary boundaries’ offers a more recent and also more all-encompassing
‘green limits’ discourse. From the mid-2000s, scientists started to propose that we
have entered a new epoch, the Anthropocene, in which human activities have
become the dominant driver of many earth system processes including climate,
bio-geochemical cycles, ecosystems and biodiversity. The extent of human
influence has grown rapidly since the Industrial Revolution, accelerating dramatic -
ally since the 1950s (Steffen et al., 2004, 2007). A series of nine planetary boundaries
has been identified, referring to the biophysical processes in the Earth’s system on
which human life depends (Rockström et al., 2009). Together, these serve to keep
the planet within Holocene-like conditions and thus define a ‘safe operating
space’ for humanity. Human actions, it is claimed, are rapidly approaching (in the
case of climate change) or have already transgressed (in the case of biodiversity and
30 Melissa Leach