Geoscience Reference
In-Depth Information
A
B
C
Figure 13.8
Global mean annual temperature anomalies (°C) from the base period 1880 to 2000 for: (A) Combined land-air and
sea-surface temperatures. (B) Sea surface. (C) Land surface.
Source
: Waple
et al
. (2002), by permission of the American Meteorological Society.
twentieth-century global warming was approximately
0.75°C, which appears to exceed natural trends (esti-
mated from statistical modelling) of 0.3°C/100 years.
There is now a wide consensus that this global warming
is largely a result of increasing greenhouse gas con-
centrations, but some characteristics of change are
problematic. For example, experiments with general
circulation models for doubled CO
2
concentrations
(see Figure 13.20) indicate significant amplification
of warming in high latitudes in winter. This signal,
attributable to feedback effects between surface albedo
and temperature associated with reduced snow cover
