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Abstract:
We examine the possibility that anthropogenic forcing (Greenhouse gases
and Sulfate aerosols, GS) is a plausible explanation for the observed
near-surface temperature trends over the Mediterranean area. For this
purpose, we compare annual and seasonal observed trends in near-surface
temperature over the period from 1980 to 2009 with the response to GS
forcing estimated from 23 models derived from CMIP3 database. We find
that there is less than a 5% chance that natural (internal) variability
is responsible for the observed annual and seasonal area-mean warming
except in winter. Using additionally two pattern similarity statistics,
pattern correlation and regression, we find that the large-scale
component (spatial-mean) of the GS signal is detectable (at 2.5% level)
in all seasons except in winter. In contrast, we fail to detect the
small-scale component (spatial anomalies about the mean) of GS signal in
observed trend patterns. Further, we find that the recent trends are
significantly (at 2.5% level) consistent with all the 23 GS patterns,
except in summer and spring, when 9 and 5 models respectively
underestimate the observed warming. Thus, we conclude that GS forcing is
a plausible explanation for the observed warming in the Mediterranean
region. Consistency of observed trends with climate change projections
indicates that present trends may be understood of what will come more
so in the future, allowing for a better communication of the societal
challenges to meet in the future.
