Climate Change 2001:
Working Group II: Impacts, Adaptation and Vulnerability
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18.2. Adaptation Characteristics and Processes

Adaptation refers both to the process of adapting and to the condition of being adapted. The term has specific interpretations in particular disciplines. In ecology, for example, adaptation refers to changes by which an organism or species becomes fitted to its environment (Lawrence, 1995; Abercrombie et al., 1997); whereas in the social sciences, adaptation refers to adjustments by individuals and the collective behavior of socioeconomic systems (Denevan, 1983; Hardesty, 1983). This chapter follows Carter et al. (1994), IPCC (1996), UNEP (1998), and Smit et al. (2000) in a broad interpretation of adaptation to include adjustment in natural or human systems in response to experienced or future climatic conditions or their effects or impacts—which may be beneficial or adverse.

18.2.1. Components and Forms of Adaptation

As both a process and a condition, adaptation is a relative term: It involves an alteration in something (the system of interest, activity, sector, community, or region) to something (the climate-related stress or stimulus). Description of an adaptation requires specification of who or what adapts, the stimulus for which the adaptation is undertaken, and the process and form it takes (Downing et al., 1997; Krankina et al., 1997; UNEP, 1998; Pittock et al., 1999; Risbey et al., 1999; Reilly and Schimmelpfennig, 2000). These elements are summarized in Figure 18-2 and addressed in turn in subsequent subsections.

Figure 18-2: Adaptation to climate change and variability (from Smit et al., 2000).

Figure 18-3: Climate change, variability, extremes, and coping range (after Hewitt and Burton, 1971; Fukui, 1979; Smit et al., 1999; and others).

18.2.2. Climate Stimuli for Adaptation

Figure 18-4: Classification of adaptation options (Burton, 1996).

Most impact and adaptation studies to date have been based on climate change scenarios that provide a limited set of possible future climates—invariably specified as average annual conditions, such as temperature and moisture. Yet the climate change-related stimuli for which adaptations are undertaken (i.e., adaptation to what?) are not limited to changes in average annual conditions; they include variability and associated extremes. Climatic conditions are inherently variable, from year to year and decade to decade. Variability goes along with, and is an integral part of, climate change (Mearns et al., 1997; Karl and Knight, 1998; Berz, 1999; Hulme et al., 1999): A change in mean conditions actually is experienced through changes in the nature and frequency of particular yearly conditions, including extremes (see Figure 18-3). Thus, adaptation to climate change necessarily includes adaptation to variability (Hewitt and Burton, 1971; Parry, 1986; Kane et al., 1992b; Katz and Brown, 1992; Downing, 1996; Yohe et al., 1996; Smithers and Smit, 1997; Smit et al., 1999). Downing et al. (1996), Etkin (1998), Mileti (1999), and others use the term "climate hazards" to capture those climate stimuli, in addition to changes in annual averages, to which the system of interest is vulnerable. Climate change stimuli are described in terms of "changes in mean climate and climatic hazards," and adaptation may be warranted when either of these changes has significant consequences (Downing et al., 1997). In water resource management, changes in the recurrence interval of extreme conditions, which are associated with changes in means, are the key stimuli (Beran and Arnell, 1995; Kundzewicz and Takeuchi, 1999).

Furthermore, for most systems and communities, changes in the mean condition commonly fall within the coping range (see Figure 18-3), whereas many systems are particularly vulnerable to changes in the frequency and magnitude of extreme events or conditions outside the coping range (Baethgen, 1997; Schneider, 1997; Rayner and Malone, 1998; Kelly and Adger, 1999). Interannual variations are key stimuli in many sectors (Rosenzweig, 1994; Adams et al., 1995; Mearns et al., 1997; Bryant et al., 2000).

Natural and human systems have adapted to spatial differences in climate. There also are examples of adaptation (with varying degrees of success) to temporal variations—notably, deviations from the annual average conditions on which climate change scenarios focus. Many social and economic systems—including agriculture, forestry, settlements, industry, transportation, human health, and water resource management—have evolved to accommodate some deviations from "normal" conditions, but rarely the extremes. This capacity of systems to accommodate variations in climatic conditions from year to year is captured in Figure 18-3 in the shaded "coping range." This capacity also is referred to as the vulnerability or damage threshold (Pittock and Jones, 2000). The coping range, which varies among systems and regions, need not remain static, as depicted in Figure 18-3. The coping range itself may change (move up or down, expand or contract), reflecting new adaptations in the system (De Vries, 1985; de Freitas, 1989; Smit et al., 2000). The coping range indicated in Figure 18-3 can be regarded as the adaptive capacity of a system to deal with current variability. Adaptive capacity to climate change would refer to both the ability inherent in the coping range and the ability to move or expand the coping range with new or modified adaptations. Initiatives to enhance adaptive capacity (Section 18.6) would expand the coping range.

18.2.3. Adaptation Types and Forms

Adaptations come in a huge variety of forms. Adaptation types (i.e., how adaptation occurs) have been differentiated according to numerous attributes (Carter et al., 1994; Stakhiv, 1994; Bijlsma et al., 1996; Smithers and Smit, 1997; UNEP, 1998; Leary, 1999; Bryant et al., 2000; Reilly and Schimmelpfennig, 2000). Commonly used distinctions are purposefulness and timing. Autonomous or spontaneous adaptations are considered to be those that take place—invariably in reactive response (after initial impacts are manifest) to climatic stimuli—as a matter of course, without the directed intervention of a public agency. Estimates of these autonomous adaptations are now used in impact and vulnerability assessment. Planned adaptations can be either reactive or anticipatory (undertaken before impacts are apparent). In addition, adaptations can be short or long term, localized or widespread, and they can serve various functions and take numerous forms (see Table 18-1).

Adaptations have been distinguished according to individuals' choice options as well, including "bear losses," "share losses," "modify threats," "prevent effects," "change use," and "change location" (Burton et al., 1993; Rayner and Malone, 1998). The choice typology has been extended to include the role of community structures, institutional arrangements, and public policies (Downing et al., 1997; UNEP, 1998; see Figure 18-4).

Table 18-1: Bases for characterizing and differentiating adaptation to climate change (Smit et al., 1999).
General Differentiating
Concept or Attribute
Examples of Terms Used
Purposefulness Autonomous

Spontaneous Purposeful
Automatic Intentional
Natural Policy
Passive Active


Proactive Reactive
Ex ante Ex post
Temporal Scope
Short term

Long term

Tactical Strategic
Instantaneous Cumulative
Spatial Scope
Retreat - Accommodate - Protect
Prevent - Tolerate - Spread - Change - Restore
Structural - Legal - Institutional - Regulatory - Financial - Technological
Cost - Effectiveness - Efficiency - Implementability - Equity

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