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Adaptation Opportunities, Constraints, and Limits Chapter 16
16
a
daptation or create opportunities (Adger et al., 2007). Key considerations
with respect to technology as an adaptation constraint include (1)
availability; (2) access (including the capacity to finance, operate, and
maintain); (3) acceptability to users and affected stakeholders; and (4)
effectiveness in managing climate risk (Adger et al., 2007; Dryden-Cripton
et al., 2007; van Aalst et al., 2008; see also Sections 9.4.4, 11.7, 14.2.4,
15.4.3). Although technology has implications for regional adaptive
capacity (e.g., Sections 22.4.5.7, 27.3.6.2, 29.6.2), in-depth exploration
of technology in the adaptation literature is often associated with specific
sectors (Howden et al., 2007; Bates et al., 2008; van Koningsveld et al.,
2008; EPA, 2009; Parry et al., 2009; Zhu et al., 2010). For example, Howden
et al. (2007) note the importance of technology options for facilitating
adaptation including applications of existing management strategies
as well as introduction of innovative solutions such as bio- and
nanotechnology (see also Hillie and Hlophe, 2007; Bates et al., 2008;
Fleischer et al., 2011). Several studies from Africa have explored how
different factors drive awareness, uptake, and use of adaptation
technologies for agriculture (Nhemachena and Hassan, 2007; Hassan and
Nhemachena, 2008; Deressa et al., 2009, 2011). While such literature
identifies specific adaptation technology options, and in some cases the
costs associated with their implementation, quantitative understanding of
the extent to which improving technology will enhance adaptive capacity
or reduce climate change impacts remains limited (Piao et al., 2010).
16.3.2.2. Physical Constraints
The capacity of human and natural systems to adapt to a changing climate
is linked to characteristics of the physical environment including the climate
itself. Recent studies have suggested that the effort required to adapt
to an increase in global mean temperature of 4°C by 2100 may be
significantly greater than adapting to lower magnitudes of change (very
high confidence; Fung et al., 2011; Gemenne, 2011; New et al., 2011;
Nicholls et al., 2011; Stafford Smith et al., 2011; Thornton et al., 2011;
Zelazowski et al., 2011; see also Section 19.5.1). This challenge arises
from the magnitude of climate change, as well as the rate (Box 16-3).
A variety of non-climatic physical factors also can constrain adaptation
efforts of natural systems (very high confidence). For example, migration
can be constrained by geographical features such as lack of sufficient
altitude to migrate vertically or barriers posed by coastlines or rivers
(Clark et al., 2011). Alternatively, Lafleur et al. (2010) identify soil
conditions as a factor that may influence the migration of North American
forests in response to climate change. Such physical barriers to migration
can also arise from human activities. Feeley and Silman (2010) note that
anthropogenic land use change can constrain the migration of Andean
plant species to higher altitudes. Meanwhile, Titus et al. (2009) analyze
state and local land use plans along the U.S. Atlantic coast and conclude
that approximately 60% of coastal land below 1meter in elevation is
anticipated to be developed in the future, posing a physical barrier to
inland migration of wetlands (see also Bulleri and Chapman, 2010;
Jackson and McIlvenny, 2011). Collectively, such physical constraints
can reduce available migration corridors and the distances over which
migration is a feasible adaptive response.
Physical constraints have important implications for human adaptation
as well (medium evidence, high agreement). For example, the distribution
a
nd abundance of water is a feature of the physical environment that
is influenced by climate. Human consumption of freshwater increasingly
is approaching the sustainable yield of surface and groundwater systems
in a number of global regions (Shah, 2009; Pfister et al., 2009, 2011a,b;
see also Sections 3.3.2, 3.5). Water-dependent enterprises in such regions
may therefore have reduced flexibility to cope with transient or long-
term reductions in water supply. This in turn influences the portfolio of
adaptation actions that can be implemented effectively to manage risk
to water security and, subsequently, agriculture and food security (Hanjra
and Qureshi, 2010) as well as energy security (Voinov and Cardwell,
2009; Dale et al., 2011). Similarly, water quality and soil quality can
constrain agricultural activities and therefore the capacity of agricultural
systems to adapt to a changing climate (Delgado et al., 2011; Kato et
al., 2011; Lobell et al., 2011; Olesen et al., 2011).
It is important to note, however, that these physical characteristics of the
environment are often amenable to management (very high confidence).
The AR4 presented case studies where adaptive capacity was linked to
the ability of human populations or communities to access physical capital
(Adger et al., 2007), such as machinery or infrastructure, to manage the
environment and associated risks. Similar findings have appeared in
more recent studies (Paavola, 2008; Thornton et al., 2008; Iwasaki et al.,
2009; Badjeck et al., 2010; Nelson et al., 2010a,b). Human modification
of the physical environment is particularly apparent in urban areas,
where the location and design of buildings and infrastructure influence
vulnerability to climate variability and change (Section 8.2.2.2). However,
past decisions regarding the built environment and its need for continual
maintenance can constrain future adaptation options and/or their costs
of implementation (Section 16.3.2.10).
16.3.2.3. Biological Constraints
Since the AR4, the literature on biological (including behavioral,
physiological, and genetic) tolerances of individuals, populations, and
communities to climate change and extremes has continued to expand
(Sections 4.4, 5.5.6, 6.2). This has resulted in a significant increase in
the number of studies describing mechanisms by which biological factors
can constrain the adaptation options for humans, nonhuman species, and
ecological systems more broadly. In particular, biological characteristics
influence the capacity of organisms to cope with increasing climate
stress in situ through acclimation, adaptation, or behavior (Jensen et
al., 2008; Somero, 2010; Tomanek, 2010; Aitken et al., 2011; Donelson
et al., 2011; Gale et al., 2011; Sorte et al., 2011) as well as the rate at
which organisms can migrate to occupy suitable bioclimatic regions
(very high confidence; Morin and Thuiller, 2009; Hill et al., 2011; Feeley
et al., 2012). Studies of humans also find age and geographic variation
among populations with respect to perceptions of thermal comfort in
indoor and outdoor space, which in turn influences the use of technologies
(e.g., air conditioning, vegetation) and behavior to adjust to the thermal
environment (Indraganti, 2010; Chen and Chang, 2012; Yang et al.,
2012; Fuller and Bulkeley, 2013; Müller et al., 2013).
The biological capacity for migration among nonhuman species is linked
to characteristics such as fecundity, phenotypic and genotypic variation,
dispersal rates, and interspecific interactions (Aitken et al., 2008; Engler
et al., 2009; Hellmann et al., 2012). For example, Aitken et al. (2008)