Climate Change and the European Water Dimension - Agri ...

Aerosols and climate change in the Mediterranean
The impact of reflecting as well as absorbing aerosols on climate was not included in
the model simulations that for the basis of the discussion of the European regional
scenarios in the TAR. As mentioned in Part A, recent observations have indicated
that high aerosol levels may cause a substantial impact on climate in several parts of
the world. Within Europe, it appears that particularly the Mediterranean basin is
subject to the influence of aerosols: several studies indicate that aerosol radiative
forcing over the summertime Mediterranean is among the highest in the world.
Studies have shown (Lelieveld et al., 2002) that the Mediterranean area has become
a global air pollution ‘crossroads’ with transport of polluted air masses from west and
eastern European from the north in the boundary layer, Asian (and to a lesser extent
North American) pollution in the mid-troposphere and Asian Pollution in the upper
troposphere. Although southerly winds are uncommon in the summer, also transport
of Saharan dust can be important in some episodes [MINATROC].
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Figure.II.1. Winter
(A), summer (B) and
annual (C) averaged–
mean temperature
anomalies (relative
to the 1901 to 1995
average) over the
period from 1500 to
2003, over the land
area 25°W to 40°E
and 35°N to 70°N
(thin black line). The
figure is reproduced
from Luterbacher et al.
(2004), where the
sources of the data
are described. Blue
lines show ±2
standard errors while
the red horizontal lines
are the ±2 standard
deviations for the
period 1901-1995. The
thick red line is a 30year
Gaussian lowpass
filtered time
series. Coldest years
are denoted in blue,
warmest years in red.
Possible
inhomogeneities in the
instrumental data
before the mid-19 th
century cannot be fully
excluded (e.g. caused
by insufficient radiation
protection)