Dealing with global climate change - Ecological Applications: Toward a Sustainable World - page 308

Control

Equilibrium model

Tundra

Taiga/Tundra

Boreal Conifer Forest

Temp. Evergreen Forest

Temperate Mixed Forest

Tropical Broadleaf Forest

Savanna/Woodland

Shrub/Woodland

Grassland

Transient model

Arid Lands

Fig. 11.3 Simulated distribution of biomes throughout the world using contrasting climate
change models. Biomes are regional ecosystems characterized by distinct types of vegetation
fi tted to the prevailing physical conditions. (a) The 'control' output represents the current
distribution of biomes. (b) Output from an 'equilibrium' model, in which the doubling of
CO 2 is assumed to produce its full temperature effect instantaneously. (c) Output for a
'transient model', in which atmospheric CO 2 responds to dynamic feedback between
atmosphere and oceans, achieving only about 65% of the eventual predicted temperature
change at the time of CO 2 doubling. Under both scenarios, forests shift northwards to
currently unforested areas. However, in temperate latitudes the transient model produces
much lower increases in temperature and larger increases in precipitation than the equilib-
rium model, with consequent differences in the distribution of biomes in the two cases.
(Tundra is a treeless plain, Boreal ( northern) Conifer Forest consists of needle-leaf trees,

while Taiga/Tundra is intermediate between the two, with tundra vegetation and scattered
conifer trees. Savanna is grassland with scattered trees.) (From Neilson & Drapek, 1998.)
(This fi gure also reproduced as color plate 11.3.)

=