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Considering Vulnerability with Relation to Freshwater Biodiversity

May 4, 2012

A key output of BioFresh will be Climate Vulnerability Index (or CVI) for freshwater biodiversity. Jon David and Paul Jepson, at the University of Oxford, are leading on the design of this index. This will be the first index to explicitly consider the vulnerability of riverine biodiversity to climate change at a global scale. As such, the design process has involved returning to first principles and specifically settling on a definition of ‘vulnerability’ that is both quantifiable and ecologically meaningful at the global scale.

So what is vulnerability? There are many existing vulnerability indices that consider the potential impact of future climate change, but the vast majority of these focus on human livelihoods and infrastructure. In spite of this, the term ‘vulnerability’ is used to mean different things within these papers and often consists of different components. The International Panel on Climate Change (IPCC) currently defines ‘vulnerability’ as a function of ‘exposure’, ‘sensitivity’ and ‘adaptive capacity’. However, after much deliberation and consultation we have decided to externalise exposure from vulnerability for the reasons outlined below.

Our definition of ‘intrinsic vulnerability’ assesses the degree to which the persistence of a population is dependent upon the prevailing climate (sensitivity) and the capacity of a population to cope with future climate change (adaptive capacity) (see Figure 1). A great advantage of conceptualising vulnerability in this way is that it removes the need to use climate and hydrological models to forecast future changes (exposure), and shifts the analysis towards a trait-based approach. This is particularly desirable due to the lack of accurate and reliable future data at a sufficiently fine-scale resolution globally.

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Figure 1: Unlike previous studies, the adopted vulnerability framework externalises exposure. This removes reliance on global climate models and future scenarios. Instead it focusses on analysing specific traits of systems that make riverine biodiversity sensitive or adaptive to climate change. A future development could see exposure scenarios coupled with the CVI to produce maps of potential impact.
 

The significance between the IPCC definition of ‘vulnerability’ and our definition of ‘intrinsic vulnerability’ can be summed up clearly in the following analogy. An individual may be immunologically pre-disposed to contracting a specific disease (sensitivity) but live in a region where vaccinations against the disease are not available (adaptive capacity). However, the disease does not occur in the region that they live (exposure). Thus, if exposure is included as component of ‘vulnerability’ the individual would have a low vulnerability index score because they are not exposed to the disease. However, if exposure is externalised from vulnerability, the individual would score as highly vulnerable due to both their high sensitivity and low adaptive capacity. Furthermore, in a scenario where the individual were to come into contact with the disease (future exposure), this could be combined with their high intrinsic vulnerability to identify them as high risk to potential impact from the disease. In our view this latter approach of externalising exposure provides a more logical and robust vulnerability index that can be combined with various exposure scenarios generate spatial maps of potential threat impacts. This approach supports the idea that such indices should be designed as ‘plug-ins’, or informatics components, that can be utilised in a wide range of future applications.

The CVI also covers exciting new ground by including an ‘Institutional Adaptive Capacity’ component.  This is an essential addition that is frequently left out of other global indices and brings a multi-disciplinary approach to this global index. Put simply, it recognises that freshwater life residing in ‘High Conservation Capacity’ regions (such as Western Europe, North America etc.) will be less vulnerable than that residing elsewhere because institutions and publics have more capacity to mobilise and form polices and management schemes that will aid climate adaptation.

It is our target to release a version 1.0 of the CVI in September 2012. The CVI makes use of the best global datasets available within the financial and time constraints of the project. As such, it is our vision that the CVI will be augmented and bettered as newer data becomes available. Next week’s blog post will consider how the CVI makes use of these global datasets and what scope there is for future development of the index.

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