Global effect of the changes

To determine the global effect of expected changes by 2100, they took the product of the numbers in Table 1 and Table 2 and scaled them relative to the largest impact (Figure 1). Using the biome level projections, allows us to make projections about how biodiversity in each biome is likely to change under each of three scenarios: (a) no interactions among the drivers,⁴ (b) antagonistic interactions among the drivers,⁵, and (c) synergistic interactions (Figure 2)⁶

Table 1: Amount of change expected in each driver of biodiversity through 2100. 1 $=$ low, 5 $=$ high (from [6]).

	Arctic	Alpine	Boreal	Grass	Savanna	Med	Desert	N temp	S temp	Tropical
Land use	1.0	1.0	2.0	3.0	3.0	3.0	2.0	1.0	4.0	5.0
Climate	5.0	3.0	4.0	2.0	2.0	2.0	2.0	2.0	2.0	1.0
N deposition	1.0	3.0	3.0	3.0	2.0	3.0	2.0	5.0	1.0	2.0
Biotic exchange	1.0	1.0	2.0	3.0	3.0	5.0	3.0	3.0	2.0	2.0
CO$_2$	2.5	2.5	2.5	2.5	2.5	2.5	2.5	2.5	2.5	2.5

Table 2: Impact of a unit change in each driver by 2100. See text for description of what each unit corresponds to. 1 $=$ low, 5 $=$ high (from [6]).

	Arctic	Alpine	Boreal	Grass	Savanna	Med	Desert	N temp	S temp	Tropical
Land use	5.0	5.0	5.0	5.0	5.0	5.0	5.0	5.0	5.0	5.0
Climate	4.0	4.0	3.5	3.0	3.0	3.0	4.0	2.0	2.0	3.0
N deposition	3.0	3.0	3.0	2.0	2.0	2.0	1.0	3.0	3.0	1.0
Biotic exchange	1.0	1.0	1.0	2.0	2.0	3.0	2.0	1.5	3.0	1.5
CO$_2$	1.0	1.0	1.0	3.0	3.0	2.0	2.0	1.5	1.5	1.0

Figure 1: Relative impact of changes in five global factors affecting biodiversity. See [6] for details.

Figure 2: Projections of biodiversity change under three scenarios. See text and [6] for details.