climate change on UAE - Stockholm Environment Institute-US Center

Figure 3-1 Global average temperature and CO 2 trends (Karl and Trenberth 2003).
<strong>climate</strong> system, a doubling of CO 2 would warm
the lower atmosphere by about 1.2ºC (Kiehl
and Trenberth, 1997).
Figure ‎3‐1 is a plot of annual mean departures
from the 1961-90 average for global temperatures,
with an underlying mean of 14.0°C, and carbon
dioxide concentrations from ice cores and
Mauna Loa (1958 on), with a mean of 333.7 ppmv
(updated from Karl and Trenberth 2003). The
plots show that the rise in CO 2 coincides with a
rise in global average surface temperatures.
Increasing CO 2 is not the only human activity
affecting our <strong>climate</strong> system and in fact, CO 2
is only responsible for about two-thirds of the
greenhouse effect, the reset being methane,
nitrous oxide, chlorofluorocarbons, and ozone.
Changes in land use, aerosol emissions from
fossil fuel burning, the storage and use of
water for agriculture, etc. are all environmental
<strong>change</strong>s that affect <strong>climate</strong> (Pielke et al., 2007).
Climatologists have tried to quantify the relative
role of various human factors on the <strong>climate</strong>
system in terms of each component’s “radiative
forcing”, which are summarized from the IPCC
Fourth Assessment Report (IPCC, 2007). Most
notably, the radiative forcing of CO 2 is the largest
single component, with natural solar irradiance
(solar variability) substantially smaller. Also,
there are human activities that counteract the
positive forcing of CO 2 . For examples, aerosols
from the burning of fossil fuels tend to reflect
heat back into space, reducing the net heat
at the surface. When all the components are
considered, there is a net positive radiative
forcing on the order of 1.5 watts per square
meter (W/m 2 ). In Figure 3-2, “positive” means
that the earth is gaining energy faster than it is
losing it (RF-Radiative Forcing; LOSU- Level of
Scientific Understanding)
Problematically, CO 2 has a relatively long
residence time in the atmosphere and while
its sources are local, it is generally globally
distributed. Recognizing that it is a strong
forcing component, the IPCC has convened
panels of experts that have developed
“storylines of the future”, which are used to
project concentrations of greenhouse gases.
These transient concentrations are then used
in Global Climate Models (GCMs) to project
the relative contribution of CO 2 (and other
factors) to future warming. Most GCMs consist
of an atmospheric module that is coupled to the
other key components of the <strong>climate</strong> system,
including representation of oceans, sea ice, and
the land surface. The major GCMs include tens
of vertical layers in the atmosphere and the
oceans, dynamic sea-ice sub-models and effects
of <strong>change</strong>s in vegetation and other land surface
characteristics (Washington, 1996; Gates et
al., 1999). The atmospheric part of a <strong>climate</strong>
model is a mathematical representation of the
behavior of the atmosphere based upon the
fundamental, non-linear equations of classical
physics. A three-dimensional horizontal and
vertical grid structure is used to track the
movement of air parcels and the ex<strong>change</strong> of
energy and moisture between parcels.
Impacts, Vulnerability & Adaptation for
Water Resources in Abu Dhabi
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