The rising concentrations of greenhouse gases, excluding any other forcings,
could cause warming over the Mediterranean region in a magnitude higher than the
global increase (Karas 2006). One forecast (Wigley 1992) indicated that average
temperatures over the region could rise by about 3.5 °C between 2000 and the latter
half of the twenty-first century. Other estimates indicate that about half of this rise
—between 1.4 and 2.6 °C—could occur by the 2020s (Rosenzweig and Tubiello
1997). Parallel evidence from numerical modeling (Kattenberg et al. 1996) for the
South Mediterranean Basin pointed to temperature increases of 1–4.5 °C (with a
mid-point of about 2.5 °C) by the latter half of the twenty-first century. Even if
emissions of greenhouse gases were stabilized by then, temperatures would continue to rise for several decades due to a time lag in the response by the oceans
(Karas 2006). Cubasch et al. (1996) estimated by modeling that until 2100, average
temperatures could rise by 2.5–3 °C across the Mediterranean Sea, 3–4 °C on
coastal areas, 4–4.5 °C over most inland areas, and up to 5.5 °C across Morocco.
There was also a similarity among the profiles of maximum summer warming
obtained by climate simulations in the Balkans and Iberian Peninsula
(Giannakopoulos et al. 2009).
These results reflect a spatial pattern of temperature distribution, wherein the
general tendency that warming over the sea lags that over the inland areas. The
twenty-first century warming tendency is also higher in inland areas compared with
coastal areas. Strong seasonal dependence is seen in the Mediterranean area with
average warming up to 4 °C in summer, above 2 °C in autumn, and below 2 °C
during spring and winter (Giannakopoulos et al. 2009). Parallel simulations of
impacts of doubling of CO 2 concentration in relation to Europe gave similar
tendencies.
Possible increases in aerosol emissions could disguise some of this warming. For
example, Mitchell et al. (1995) showed that aerosols may reduce warming over the
Mediterranean region by 1–2 °C for the period 2030–2050, relatively to the nineteenth century. Hasselmann et al. (1995) reported that the net effect of aerosols
could even show a hypothetical cooling over the central Mediterranean in summer
over the next few decades. Indeed, the presence of aerosols may locally counter the
greenhouse effects but, unlike GHGs, their effects are transient, lasting weeks or
months. Overall, aerosols could exert some influence, and long-term climate projections cannot ignore their effects (Karas 2006).
Giannakopoulos et al. (2005) formulated climate predictions over the period
2025–2050 (average values under A1B, B1, and A2 scenarios of the AR4 Report),
with different uncertainty ranges, and assuming a conservative global 2 °C temperature increase during the twenty-first century. In the case of the Iberian Peninsula, an increase of 14–42 days in the summer, with temperatures higher than 30 °
C, was projected.
Modeling projections between now and the second half of the twenty-first
century in European areas, of days per year with maximum temperatures higher
than 30 °C, pointed to a significant increase of the areas corresponding to the range
of 100–200 days. This heating effect is particularly accentuated throughout the
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8 Fundamentals of Global Carbon Budgets and Climate Change
could cause warming over the Mediterranean region in a magnitude higher than the
global increase (Karas 2006). One forecast (Wigley 1992) indicated that average
temperatures over the region could rise by about 3.5 °C between 2000 and the latter
half of the twenty-first century. Other estimates indicate that about half of this rise
—between 1.4 and 2.6 °C—could occur by the 2020s (Rosenzweig and Tubiello
1997). Parallel evidence from numerical modeling (Kattenberg et al. 1996) for the
South Mediterranean Basin pointed to temperature increases of 1–4.5 °C (with a
mid-point of about 2.5 °C) by the latter half of the twenty-first century. Even if
emissions of greenhouse gases were stabilized by then, temperatures would continue to rise for several decades due to a time lag in the response by the oceans
(Karas 2006). Cubasch et al. (1996) estimated by modeling that until 2100, average
temperatures could rise by 2.5–3 °C across the Mediterranean Sea, 3–4 °C on
coastal areas, 4–4.5 °C over most inland areas, and up to 5.5 °C across Morocco.
There was also a similarity among the profiles of maximum summer warming
obtained by climate simulations in the Balkans and Iberian Peninsula
(Giannakopoulos et al. 2009).
These results reflect a spatial pattern of temperature distribution, wherein the
general tendency that warming over the sea lags that over the inland areas. The
twenty-first century warming tendency is also higher in inland areas compared with
coastal areas. Strong seasonal dependence is seen in the Mediterranean area with
average warming up to 4 °C in summer, above 2 °C in autumn, and below 2 °C
during spring and winter (Giannakopoulos et al. 2009). Parallel simulations of
impacts of doubling of CO 2 concentration in relation to Europe gave similar
tendencies.
Possible increases in aerosol emissions could disguise some of this warming. For
example, Mitchell et al. (1995) showed that aerosols may reduce warming over the
Mediterranean region by 1–2 °C for the period 2030–2050, relatively to the nineteenth century. Hasselmann et al. (1995) reported that the net effect of aerosols
could even show a hypothetical cooling over the central Mediterranean in summer
over the next few decades. Indeed, the presence of aerosols may locally counter the
greenhouse effects but, unlike GHGs, their effects are transient, lasting weeks or
months. Overall, aerosols could exert some influence, and long-term climate projections cannot ignore their effects (Karas 2006).
Giannakopoulos et al. (2005) formulated climate predictions over the period
2025–2050 (average values under A1B, B1, and A2 scenarios of the AR4 Report),
with different uncertainty ranges, and assuming a conservative global 2 °C temperature increase during the twenty-first century. In the case of the Iberian Peninsula, an increase of 14–42 days in the summer, with temperatures higher than 30 °
C, was projected.
Modeling projections between now and the second half of the twenty-first
century in European areas, of days per year with maximum temperatures higher
than 30 °C, pointed to a significant increase of the areas corresponding to the range
of 100–200 days. This heating effect is particularly accentuated throughout the
294
8 Fundamentals of Global Carbon Budgets and Climate Change