Table 1.

Advantages and disadvantages of the two components of major modelling approaches used to estimate loss of biodiversity due to climate change. See Figure 3 for illustrations of how the two components can be combined to estimate biodiversity loss.

	Advantages	Disadvantages	Key references
Biodiversity range model component
• Bioclimatic  Envelope Models  (BEM)	-can be applied to a large number of species and a variety of taxonomic groups - implicitly capture many ecological processes in the relationship between occurrence data and spatial information - require few data	- do not explicitly account for mechanisms that mediate species range - may handle novel climates poorly - lack temporal dynamics - assume that the current distribution of a species is a good indicator of favourable climate	(3, 5, 6, 11, 12, 15, 16, 17)
• Dynamic  Vegetation  Models (DVMs)	- include the dynamics of plant growth, competition and, in a few cases, migration - allow the identification of future trends in ecosystem function and structure - can be used to explore feedbacks between biosphere and atmospheric processes	- require detailed physiological data - do not include plant interactions with other taxonomic groups - limit biodiversity to a very small number of plant functional types. - do not take into account fine scale spatial heterogeneity - are not adapted for predicting species extinctions at local scales	(1, 4, 7, 17, 18, 19)
Species loss model component
• Species Area  Relationships  (SAR)	- are easy to couple with distribution models because they are based on range or habitat loss - can be applied to a variety of taxonomic groups - require few data	- use values of key parameters that are not well constrained - lack empirical evidence concerning applicability of SAR for climate change or at species range level - lack temporal dynamics - don’t account for processes influencing extinction rates (e.g., population dynamics, adaptive responses)	(3, 18, 20, 21)
• IUCN status  methods	- use a widely accepted measure of threat - are simple to couple with distribution models because partly based on criteria of range or habitat loss	- depend on thresholds that are somewhat arbitrary - rely on sole criteria of declining range size in most studies - often don’t respect time frame for declines (i.e., 10 years or 3 generations in most cases)	(3, 5, 22)
• Dose response  relationships	- are anchored in measured responses of biodiversity to global change drivers - can assess the impact of a wide range of global change factors alone or their cumulative effects - can include time lags	- “undisturbed” ecosystems used as baseline are difficult to define - inadequately account for interactions between global change drivers. - lack validation at large regional or global scales - use metrics that are difficult to relate to common biodiversity indices	(7, 8)