Editing IPCC:AR6/WGII/Chapter-2 (section)

==== 2.5.1.2 Risk Assessment and Non-Modelling Approaches ====

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In order to add realism and reliability to risk assessments at the species and community levels, non-modelling approaches, based on known biological traits or processes as well as on expert opinion ( [[#Camac--2021|Camac et al., 2021]] ), are used to temper model outputs with ground-based validation. Trait-based assessment approaches use species’ biological characteristics as predictors of sensitivity, adaptive capacity and extinction risk due to climate change. Climate exposure can be estimated using GIS-based modelling, statistical programs or expert judgment ( [[#Chin--2010|Chin et al., 2010]] ). These trait-based approaches are widely applied to predict responses of biodiversity to climate change because they do not require modelling expertise or detailed distibutional data ( [[#Pacifici--2015|Pacifici et al., 2015]] ; [[#Willis--2015|Willis et al., 2015]] ). Most of these methods have not been independently validated and do not allow direct comparison of vulnerability and risk across taxonomic groups.

Some studies have combined two or three approaches for the assessment of climate change risk to biodiversity, in order to capture the advantages of each and avoid their limitations. [[#Warren--2013|Warren et al. (2013)]] used combinations of SDMs and trait-based approaches to estimate the proportions of species losing their climatically suitable ranges under the various future scenarios of climate and dispersal rate. Similarly, spatial projections of exposure to climate change were combined with traits to assess the vulnerability of sub-Saharan amphibians ( [[#Garcia--2014|Garcia et al., 2014]] ). [[#Laurance--2012|Laurance et al. (2012)]] combined 31 functional groups of species and 21 potential drivers of environmental change, in order to assess both the ecological integrity and threats to protected tropical areas on a global scale. [[#Keith--2014|Keith et al. (2014)]] used a combination of three approaches (SDMs–trait–mechanistic) to determine how long before extinction a species would become eligible for listing as threatened, based on the IUCN Red List criteria.

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