Geoscience Reference
In-Depth Information
Figure 24.3
Multimodel mean changes in (a) precipitation (mm/day), (b) soil moisture content (%), (c) runoff (mm/day) and
(d) evaporation (mm/day). To indicate consistency in the sign of change, regions are stippled where at least 80 % of models
agree on the sign of the mean change. Changes are annual means for the SRES A1B scenario for the period 2080-2099 relative to
1980-1999 (after Meehl
et al.
, 2007).
decades to centuries to global mean temperature. For fu-
ture global temperature scenarios of the Intergovernmen-
tal Panel on Climate Change's Fourth Assessment Report,
the relationship projects a sea-level rise ranging from 75
to 190 cm for the period 1990-2100.
zone geomorphology to future climate change. The most
complex and sophisticated are not necessarily the most
useful or accurate. All involve climate change projections
from climate models, although a key requirement is also
the thorough if not quantitative understanding of geomor-
phic systems and their thresholds and sensitivity to forc-
ing factors such as precipitation, wind, temperature and
evaporation.
The simplest approach is to describe qualitatively
what likely impacts will emerge from the changing cli-
mate, often on the basis of changing climate variables
(precipitation, wind, temperature, wind and evaporation)
over the forthcoming decades. Whereas much of arid
zone geomorphology has been concerned with interpre-
tation of past environments from the analysis of land-
forms, this approach is essentially the opposite - going
from a set of altered climatic conditions to the inferred
landscape response. While this simple approach under-
pins the majority of first-order assessments of climate
change vulnerability across a range of disciplines, par-
ticularly at the regional and country level, the specific
difficulties lie in determining the nonlinear responses of
24.3.1
Methods of establishing climate change
impacts in arid zones
There are at least three methods, ordered by complex-
ity and sophistication, for establishing responses of arid
Table 24.2
Global mean sea-level rise in cm for the end of
the twenty-first century relative to the last two decades of the
twentieth century from IPCC AR4. Results are shown for three
emission scenarios. The range of sea level rise is therefore
18-59 cm.
Scenario
Change in sea level in cm
B1
0.18-0.38
A1B
0.21-0.48
