Climate change affects agriculture, the people who practice it, and the people who consume the food it produces through a variety of pathways. Some of these are sketched out in the overview Climate Change and Agriculture: Cause and Impact (make this a hotlink) and in more detail in Water and Adaptation to Climate Change (make this a hotlink). In the technical literature, the impact pathways between climate change and human well-being are often described in a more formal conceptual way, using concepts of vulnerability, sensitivity, adaptive capacity, and others. This overview defines these concepts briefly and shows their inter-relationships.
Background
The scientific literature, as consolidated by the Intergovernmental Panel on Climate Change (IPCC), demonstrates that the ongoing changes in climate will have a wide range of impacts on human populations that vary in nature and intensity across the world. It has been said that, while warming is global, climate change is local.
Although climate change will have impacts that can be positive for some areas and groups of people, the most significant impacts are expected to be negative. Recent assessments suggest that some effects are advancing more rapidly than predicted by the IPCC, and the impacts can be more severe[1]. Any positive impacts for agriculture, in the form of increased rainfall and longer growing seasons, are expected mostly in the northern hemisphere, affecting the higher latitudes of North America and Eurasia. Areas where lower precipitation, coupled with elevated temperatures, will cause negative changes in water availability in general, and harmful affects on agriculture in particular, include the Mediterranean region, Southern Africa, the Western United States and Northern Mexico, and Brazil.
Moreover some groups within these regions will be more strongly affected than others. In order to design adaptive strategies, it is necessary to assess the regions, systems, and population groups which are most vulnerable to the impacts of climate change.
Key concepts
Vulnerability
Vulnerability is defined in different ways by different users. The general definition that has emerged in the climate change
|
Vulnerability is the degree to which a system is susceptible to, or unable to cope with, adverse effects of climate change, including climate variability and extremes. Vulnerability is a function of the character, magnitude, and rate of climate change and variation to which a system is exposed, its sensitivity, and its adaptive capacity. IPCC 4AR, WG-II, SPM.
|
literature is the one articulated by the IPCC shown in the box at right. This concept of vulnerability subtends a framework which links human welfare to climate through the key concepts of exposure, sensitivity and adaptive capacity. These concepts are defined briefly below.
Exposure
Exposure is the nature and extent of the changes in climate that a region experiences or will experience. It is expressed in the form of outputs of global circulation models (GCMs), and, increasingly, as results of analyses of past climatic records showing longer-term changes resulting from global warming. The GCM results must generally be down-scaled, using more fine-grained regional models to yield regionally-useful results. There is still substantial uncertainty in these predictions, stemming both from the uncertainty inherent in the models themselves and from the uncertain trajectory of future greenhouse gas (GHG) emissions as a result of our actions.
Sensitivity
The sensitivity of a system to changes in climate specifies how its key natural resource-based systems respond to an exposure to climate change. Responses, of course, will differ from region to region and ecosystem to ecosystem. As precipitation decreases, for example, things like river flows, groundwater recharge, populations of native plants and animals, and agricultural crops will change in linked ways. A huge variety of factors influence system sensitivity. For river discharge, for example, factors include the degree to which snowmelt is a water source; share of groundwater contribution to river flow; evaporation rate from open water surfaces, the response of native vegetation extracting water from river margins, and so on. Modeling is usually needed for a comprehensive understanding of the interrelated causes and effects.
Adaptation
Adaptation is the key to a society’s ability to deal with climate change. It comprises the sum of actions taken to change behavior, shift priorities, produce needed goods and services, and plan and act in ways that reduce harmful climate change impacts or transform them into positive opportunities. Adaptation can be anticipatory or reactive, come from the public or the private sector, and be short or long range in perspective.
Adaptive capacity
Adaptive capacity is the ability to adapt. It is a function of a society’s stock of infrastructure, its human resources, its technology base, its educational system, its research capacity, its wealth, its natural resource base, the structure of its economy, and many other factors. This is a key intervention point in the vulnerability paradigm.
With respect to climate change, adaptations are adjustments or interventions which are undertaken to manage the losses or take advantage of the opportunities presented by a changing climate. Adaptive capacity is the ability of a system to adjust to climate change to moderate potential damages, to take advantage of opportunities, or to cope with the consequences (IPCC, 2007).
