Mediterranean Basin. The Iberian Peninsula is particularly affected with a significant area presumably included in the 100–200-day class (ACACIA Project 2000).
According to the AR4 Report, doubling of CO 2 atmospheric concentration will
induce a temperature variation ranging from −5 to 2.5 °C in the Mediterranean
Basin, with the Iberian Peninsula being one of the areas with the largest temperature
increases (Grunderbeeck and Tourre 2008). Even if the concentration of GHG was
maintained at the 2000 levels, an increase of 0.1 °C in air temperature per decade
would be expected.
Global and regional circulation models (RCM), show uncertainties that can be
parameterized and that might be expected to decrease over time, in the light of new
knowledge on climate. Among the main sources of uncertainty are the incomplete
knowledge of the physical mechanisms and processes dealt with numerical models
for regional climate, the socioeconomic impact, and on the human demographic and
technological evolution. This latter aspect is important for assessing specific
impacts on climate change of agriculture, industry, water resources, and energy.
Parameterization schemes in the RCMs are based on the knowledge of observed
values that might be exceeded in the future. For example, some projections of
temperature ranges in the Mediterranean Basin are based on average air temperature
increases which may not be representative of current daily average temperature
change (Grunderbeeck and Tourre 2008).
8.6.3 Changes in Precipitation and Moisture Availability
Global warming has been linked with increases in average daily precipitation,
followed by increased water vapor in a warmer atmosphere. Increases in annual
rainfall were recorded in many mid- to upper latitudes, except for the Mediterranean
Basin where a decreasing trend has been observed (e.g., Alpert et al. 2002). Since
1900, precipitation decreased by over 5% over much of the land bordering the
Mediterranean Sea, apart from the contiguous coastland extending from Tunisia to
Libya where it increased slightly (Karas 2006).
In the Central-Western Mediterranean Basin encompassing Italy and Spain, the
total precipitation decreased by 10–20%. In the southern Mediterranean strip,
including Southern Italy, Southern Spain, and Tunisia, a higher global decrease of
26% occurred, and in the Eastern Mediterranean mixed tendencies of rainfall with
mean precipitation did not change, and heavy precipitation events increased
(Groisman et al. 2005). Other evidence clearly shows that rainfall and specific and
relative atmospheric humidity, predictors of precipitation, have decreased in the
Iberian Peninsula and Greece over the second half of the twentieth century, and this
correlated positively with decreased rainfall (e.g., Grunderbeeck and Tourre 2008).
For Central and Southern Israel, an increasing trend in total rainfall was recorded
over the period 1951–1990 and is likely to be associated with large modifications in
the land cover and land use. Alpert et al. (2002) noted that in the Eastern
Mediterranean region, mean precipitation during the rainy season did not change
8.6 A Brief Analysis of the Mediterranean …
295
According to the AR4 Report, doubling of CO 2 atmospheric concentration will
induce a temperature variation ranging from −5 to 2.5 °C in the Mediterranean
Basin, with the Iberian Peninsula being one of the areas with the largest temperature
increases (Grunderbeeck and Tourre 2008). Even if the concentration of GHG was
maintained at the 2000 levels, an increase of 0.1 °C in air temperature per decade
would be expected.
Global and regional circulation models (RCM), show uncertainties that can be
parameterized and that might be expected to decrease over time, in the light of new
knowledge on climate. Among the main sources of uncertainty are the incomplete
knowledge of the physical mechanisms and processes dealt with numerical models
for regional climate, the socioeconomic impact, and on the human demographic and
technological evolution. This latter aspect is important for assessing specific
impacts on climate change of agriculture, industry, water resources, and energy.
Parameterization schemes in the RCMs are based on the knowledge of observed
values that might be exceeded in the future. For example, some projections of
temperature ranges in the Mediterranean Basin are based on average air temperature
increases which may not be representative of current daily average temperature
change (Grunderbeeck and Tourre 2008).
8.6.3 Changes in Precipitation and Moisture Availability
Global warming has been linked with increases in average daily precipitation,
followed by increased water vapor in a warmer atmosphere. Increases in annual
rainfall were recorded in many mid- to upper latitudes, except for the Mediterranean
Basin where a decreasing trend has been observed (e.g., Alpert et al. 2002). Since
1900, precipitation decreased by over 5% over much of the land bordering the
Mediterranean Sea, apart from the contiguous coastland extending from Tunisia to
Libya where it increased slightly (Karas 2006).
In the Central-Western Mediterranean Basin encompassing Italy and Spain, the
total precipitation decreased by 10–20%. In the southern Mediterranean strip,
including Southern Italy, Southern Spain, and Tunisia, a higher global decrease of
26% occurred, and in the Eastern Mediterranean mixed tendencies of rainfall with
mean precipitation did not change, and heavy precipitation events increased
(Groisman et al. 2005). Other evidence clearly shows that rainfall and specific and
relative atmospheric humidity, predictors of precipitation, have decreased in the
Iberian Peninsula and Greece over the second half of the twentieth century, and this
correlated positively with decreased rainfall (e.g., Grunderbeeck and Tourre 2008).
For Central and Southern Israel, an increasing trend in total rainfall was recorded
over the period 1951–1990 and is likely to be associated with large modifications in
the land cover and land use. Alpert et al. (2002) noted that in the Eastern
Mediterranean region, mean precipitation during the rainy season did not change
8.6 A Brief Analysis of the Mediterranean …
295