Mediterranean climate: trends and projections

titolo 

International workshop 

On Climate Change in the Mediterranean and the Middle East 

University of Cairo, 9-11 June 2008 

Mediterranean climate: 

trends and projections 

Piero Lionello, University of Salento, Italy

Contents 

• Remarks on the Mediterranean climate 

• A review of present trends 

• Information from climate projections 

Sommario 




University of Cairo, 9-11 June 2008

koeppen 

Vladimir Petrovič Köppen 

Russian geographer , botanist and climatologist 

(S. Petersburg, 1846 – Graz, 1940)

Classificazone 1 

Main groups 

A tropical climate 

B arid climate: 

C mid latitude temperate climate 

D mid latitude cold climate 

E polar climate 

H mountain climate 

Sub-groups : 

S steppe W desert f wet w winter dry season 

s summer dry season m: rain forest 

Af, Am: monsoon, tropical rain forest. Aw: savannah 

BS: steppe. BW: desert. 

Cw: temperate mid latitude with dry winter Cf: temperate mid latitude without 

dry season Cs: temperate mid latitude with dry summer. 

Df: cold rainy during the whole year. 

ET: tundra. EF: frost 

3 rd level classification 

a, b,c hot summer (T warmest month > 22°C), warm summer (warmest month < 

22°C), cold summer (T less than 4 months > 10°C (climates C and D). 

d: very cold winter (T coldest month < -38°C (climate D). 

h, k: hot, cold (average year temperature higher/lower than 18°C < (climate B).

Updated world map of 

the Köppen-Geiger 

climate classification 

M. C. Peel, B. L. 

Finlayson, and T. A. 

McMahon 

Hydrol. Earth Syst. Sci. 

Discuss., 4, 439–473, 

2007 

The 30 possible climate types are divided (without accounting for H)into: 

3 tropical (Af, Am and Aw), 4 arid (BWh, BWk, BSh and BSk), 9 temperate (Csa, 

Csb, Csc, Cfa, Cfb, Cfc, Cwa, Cwb and Cwc), 12 cold (Dsa, Dsb, Dsc, Dsd, Dfa, Dfb, 

Dfc, Dfd, Dwa, Dwb, Dwc and Dwd) and 2 polar (ET and EF). 

Koeppen global

Med climate 





What is the Mediterranean Climate ?

Koeppen eu 

10 out of 30 Köppen climate 

types are present around 

the Mediterranean Sea

•Csa/Csb temperate climate with dry hot/warm summer 

season 

•Cfa/Cfb temperate climate without dry season and with 

hot/warm 

•Dsa, Dfb cold climate, without dry season but warm summer 

and with hot dry summer 

•BWh BWk hot and cold desert, BSh BSk hot and cold 

steppe 

Koeppen 

considerazioni 

Large areas of the Mediterranean region do not 

have the “CsA/Csb Mediterranean” climate 

… and there is some Mediterranean climate 

outside the Mediterranean region

Tise T past 

Past winter temperature (DJF) 

Luterbacher J. et al. (2005), Mediterranean climate variability over the last 

centuries: a review In P.Lionello, P.Malanotte-Rizzoli, R.Boscolo (eds) 

Mediterranean Climate Variability. Amsterdam: Elsevier (NETHERLANDS).

Warmestcoldest 

Luterbacher J. 

et al. (2005),

Tise prec past 

Past winter precipitation (DJF) 


et al. (2005),

Driest-wettest 


et al. (2005),

Considerazioni: 

time variabiity 


Large variability at inter-annual and interdecadal 

scale is a basic characteristic of 

the Mediterranean region 

…However, the temperature increase 

during the second half of the 20 th century 

in unprecedented in historical records

Tendenze 20mo 

secolo 


Focus on 20 th century 

Graphics based on CRU climatology, interpolated from station 

data to 0.5 degree lat/lon grid ( New, M., M. Hulme and P. Jones, 

1999: Representing twentieth-century space-time climate 

variability. Part I: Development of a 1961-90 mean monthly 

terrestrial climatology. J. Climate, 12, 829-856.

Pre_season 

1901-1925 

DJF 

JJA 

Precipitation 1901 - 1925 

MAM 

SON

Pre_season_19 

75_2000 

DJF 

JJA 

Precipitation 1975 -2000 

MAM 

SON

Pre_MK 1901- 

2000 

DJF 

JJA 

Precipitation trends 1901 - 1925 

MAM 

SON

Pre_MKmsk 

1901-1925 

DJF 

JJA 


MAM 

SON

Pre_MK 1975- 

2000 

DJF 

JJA 


MAM 

SON

Pre_MKmsk 

1975-2000 

DJF 

JJA 


MAM 

SON

Pre_MK_msk 

1901-2000 

DJF 

JJA 

Precipitation trends 1901 -2000 

MAM 

SON

Elena wet season 

Wet season precipitation trend (1950-1999) 

Acknowledgement: Xoplaki, 2002; Xoplaki et al., 2004 

mm/50years

Elena dry season 

Dry season precipitation trend (1950-1999) 

Acknowledgement: Xoplaki, 2002; Xoplaki et al., 2004 

mm/50years

tmp_season_19 

01_1925 

DJF 

JJA 

Temperature 1901 - 1925 

MAM 

SON

tmp_season_19 

01_2000 

DJF 

JJA 

Temperature 1975 - 2000 

MAM 

SON

tmp_MKmsk_19 

01_1975 

DJF 

JJA 

Temperature trend 1901 - 1925 

MAM 

SON

tmp_MKmsk_19 

75_2000 

DJF 

JJA 


MAM 

SON

Tmp_MKmsk- 

1901-2000 

DJF 

JJA 


MAM 

SON

Comment tmp 

and pre 

Though there is a possibly widespread over-perception 

of precipitation trends, reduction of (winter) 

precipitation is observed over large areas of the 

Mediterranean region. The signal for temperature is 

much clearer than for precipitation: there is positive 

trend with an acceleration during the last part of the 

20th century involving the whole Mediterranean region 

University of Cairo, 9-11 June 2008

Models 

Climate model projections 

Schematic view of the components of the climate 

system, their processes and interactions. 

FAQ 1.2, Figure 1 

From IPCC 4 th AR

Scenarios 

CO 2 emissions in SRES (Nakicenovic et al, 2000) : 

• A-B rispettivamente forte e ridotto fabbisogno 

energetico; 

From IPCC 4 th AR 

• 1-2 rispettivamente sviluppo mondiale omogeneo e 

eterogeneo.

Model mean reliability 


Figure TS.23. (a) Global mean surface 

temperature anomalies relative to the 

period 1901 to 1950, as observed (black 

line) and as obtained from simulations 

with both anthropogenic and natural 

forcings. The thick red curve shows the 

multi-model ensemble mean and the 

thin lighter red curves show the 

individual simulations. Vertical grey lines 

indicate the timing of major volcanic 

events. (b) As in (a), except that the 

simulated global mean temperature 

anomalies are for natural forcings only. 

The thick blue curve shows the multimodel 

ensemble mean and the thin 

lighter blue curves show individual 

simulations. Each simulation was 

sampled so that coverage corresponds 

Figure TS.23 

to that of the observations. {Figure 9.5}

Mean projection 

Figure 10.5 


Time series of globally averaged (left) surface warming (surface air temperature change, °C) and (right) precipitation 

change (%) from the various global coupled models for the scenarios A2 (top), A1B (middle) and B1 (bottom). 

Numbers in parentheses following the scenario name represent the number of simulations shown. Values are annual 

means, relative to the 1980 to 1999 average from the corresponding 20th-century simulations, with any linear trends in 

the corresponding control run simulations removed. A three-point smoothing was applied. Multi-model (ensemble) 

mean series are marked with black dots. See Table 8.1 for model details.

Ensemble 

mean med 





Ensemble mean projections for the 

Mediterranean region 

Using GLOBAL models

MODEL Grid interval 20C B1 A1B A2 

CCMA-3-T47 

CNRM-CM3 

CSIRO-MK3 

GFDL-CM2-0 

GFDL-CM2-1 

GISS-AOM 

GISS-E-R 

INMCM3 

IPSL-CM4 

MIROC3-2H 

MIROC3-2M 

MIUB-ECHO-G 

MPI-ECHAM5 

MRI-CGCM2 

NCAR-CCSM3 

NCAR-PCM1 

UKMO-HADCM3 

List of models 

~2.7 deg 

~2.8 deg 

~2.3 deg 

~2.2 deg 

~2.2 deg 

~3.5 deg 

~4.5 deg 

~4.5 deg 

~3.0 deg 

~1.2 deg 

~2.8 deg 

~3.2 deg 

~2.3 deg 

~2.8 deg 

~1.4 deg 

~2.8 deg 

~3.0 deg 

5 4 4 2 

1 1 1 1 

2 1 1 1 

3 1 1 1 

3 0 1 1 

2 2 2 0 

1 1 2 1 

1 1 1 1 

1 1 1 1 

1 1 1 0 

3 3 3 3 

5 3 3 3 

3 3 2 3 

5 5 5 5 

8 8 6 4 

4 2 3 4 

1 1 1 1 

List of models, grid interval (atmosphere) and experiments used in this work. 20C 

indicates experiments for the 20c century, B1, A1B and A2, experiments for the 21st 

century under forcing deriving from the corresponding IPCC emission scenarios. The 

grid interval is approximate, as it may vary across latitudes and may be different in 

the longitude and latitude directions. More detailed information on models and 

experiments is available the PCMDI web site http://www-pcmdi.llnl.gov for.

isoluzione 

space resolution !!!! 

One obvious limitation of these simulations is resolution. 

This might have important consequences for the climate 

change signal in region where it shows a sharp gradient, 

likely associate with the geomorphology of the region: 

precipitation in the middle east in Summer and Fall, 

precipitation along the northern boundary of the 

Mediterranean region (Pyrenees, Alps, Balkans).

Risoluzione 5 

5 degs

Risoluzione 4 

4 degs

Risoluzione 3 

3 degs

Risoluzione 2 

2 degs

Risoluzione 1 

1 degs

Risoluzionem 

0.5 

0.5 degs

Risoluzione 0.2 

0.2 degs

Risoluzione 0.1 

0.1 degs

CC_Pre B1 

Precipitation change (%, 2071-2100 minus 1961-1990), 

MGME ensemble average, B1 scenario 

DJF MAM 

JJA 

Figure 6 

SON 

from Giorgi and Lionello, 2007

CC_Pre A1B 


MGME ensemble average, A1B scenario 

DJF MAM 

JJA 

Figure 4 

SON 



MGME ensemble average, A2 scenario 

DJF MAM 

JJA 

CC_Pre A2 

Figure 7 

SON 


CC_tmp_A1B 

Temperature change (C, 2071-2100 minus 1961-1990), 


DJF 

JJA 

Figure 5 

MAM 

SON 


Precipitation change (%) 

Temperature change (C) 

0 

-5 

-10 

-15 

-20 

-25 

-30 

-35 

6 

5 

4 

3 

2 

1 

0 

(2081-2100) minus (1961-1980) 

DJF MAM JJA SON 

B1 

A1B 

A2 

B1 

A1B 

A2 

Tmp-prec total 

MGME ensemble average change in 

mean precipitation (upper panel) 

and mean surface air temperature 

(lower panel) for the full 

Mediterranean region, the four 

seasons and different scenario. The 

changes are calculated between the 

periods 2081-2100 and 1961-1980 

and include only land points. Units 

are % of 1961-1980 value for 

precipitation and degrees C for 

temperature 


CC_SLP 

SLP change (mb, 2071-2100 minus 1961-1990), 


DJF 

JJA 

MAM 

SON

CC_GPH500 

500 Gph change (mb, 2071-2100 minus 1961-1990), 


DJF 

JJA 

Figure 3 

MAM 

SON 



Precipitation Change (%) 


0 

-5 

-10 

-15 

-20 

-25 

-30 

5 

4.5 

4 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 


2001-2020 

2021-2040 

2041-2060 

2061-2080 

2081-2100 

2001-2020 

2021-2040 

2041-2060 

2061-2080 

2081-2100 


Precipitation change (%) 


-10 

-12 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

(1981-2000) minus (1961-1980) 

4 

2 

0 

-2 

-4 

-6 

-8 

0 


Observed 

MGME 

Observed 

MGME 

caveaut 

Observed (CRU data) and MGME 

ensemble average change in 

precipitation (upper panel) and 

surface air temperature (lower 

panel) for the four seasons over 

the full Mediterranean region (land 

only) 1981-2000 minus 1961-1980. 

Units are % of 1961-1980 value for 

precipitation and degrees C for 

temperature. 


Modelli 

regionali 

Regional Climate models 



University of Cairo, of Cairo, 9-11 9-11 June June 2008 

2008

RegCM experiment design 

Giorgi, F., X. Bi and J.S. Pal , 2004 a and b 

• Global Model: Hadley Centre 

HadAMH 

– Dx = 1.25 lat x 1.875 lon 

– SST from HadCM3 run 

– Coupled sulfur model 

• Regional model: ICTP RegCM 

– Dx = 50 km 

– SST, GHG and sulfate from 

HadAMH 

– aerosol effects 

• Simulation periods 

– 1961-1990 : Reference run 

– 2071-2100 : Scenario run 

• Scenarios: A2, B2

Risoluzionem 

0.5 

0.5 degs

CTR 

RegCM model 

D 

R 

Y 

W 

E 

T 

S 

E 

A 

S 

O 

N 

S 

E 

A 

S 

O 

N 

CRU 

Observed climatology

Jan 

Feb 

Mar 

Precipitation A2-CTR 

Apr 

May 

Jun 

mm 

Jul 

Aug 

Sep 

Oct 

Nov 

Dec

Ebro 

Rhone 

Mediterranean River basins 

Po Croatian rivers 

Greek rivers 

Turkish rivers

Precipitation 

= 

Water balance 

(P-E) 

Greece and Turkey 

- 

Evaporation 

Drier autumn and 

(partially) spring 

for Greek and 

Turkish rivers

JAN FEB MAR 

APR MAY JUN 

JUL AUG SEP 

OCT NOV DEC

Climate change assessment for Mediterranean agricultural 

areas by statistical downscaling 

L. Palatella · M. Miglietta · P. Paradisi · P. Lionello (submitted)


Population growth !?!?!?!

90000 

80000 

70000 

60000 

50000 

40000 

30000 

20000 

10000 

0 


1955 1 1970 2 1985 3 2000 4 2015 5 2030 6 

France 

Italy 

Spain 

Turkey

25000 

20000 

15000 

10000 

5000 

0 

70000 

60000 

50000 

40000 

30000 

20000 

10000 

0 

1955 1 1970 2 1985 3 2000 4 2015 5 2030 6 

1955 1 1970 2 1985 3 2000 4 2015 5 2030 

6 

Cyprus 

Gaza Strip 

Israel 

Lebanon 

Syria 

Algeria 

Egypt 

Libya 

Morocco 

Tunisia

Considerazioni: 

time variabiity 

Large variability at inter-annual and inter-decadal 

scale is a basic characteristic of the Mediterranean 

region…However, the temperature increase during 

the second half of the 20th century in unprecedented 

in historical records 

Though there is a possibly widespread overperception 

of precipitation trends, reduction of 

(mainly winter) precipitation is observed over large 

areas of the Mediterranean region. The signal for 

temperature is much clearer than for precipitation: 

there is positive trend with an acceleration during 

the last part of the 20th century involving the whole 

Mediterranean region

Reduced precipitation is a very likely consequence of 

anthropogenic climate change in large parts of the 

Mediterranean (including Middle east) 

Evidences from global models are not flawless. They 

need further confirmation, possibly based on regional 

analysis 

Regionalization techniques (dynamical versus 

statistical) do not always agree 

Concerning impacts, other factors (such as 

population dynamics) are likely to have larger effects 

than climate change (multi-sector approach is 

needed)





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Mediterranean climate: trends and projections

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