Climate system and impacts in the Mediterranean Basin · Climate system and impacts in the...

Climate system and impacts in the Mediterranean Basin

Silvio Gualdi

Centro Euro-Mediterraneo sui Cambiamenti Climatici,Centro Euro-Mediterraneo sui Cambiamenti Climatici,

Istituto Nazionale di Geofisica e Vulcanologia

Outline

1. The scientific basis of climate change

2. Overview of the tools we use to investigate the climate change

and its impacts: climate models and scenario simulations

Scope: understanding the dynamic of climate change

and its physical impacts in the Mediterranean basin

and its impacts: climate models and scenario simulations

3. Application to the Mediterranean basin: the climate change

signal in the Mediterranean area

3.a: impacts on the hydrological cycle

3.b: impacts on the sea-level

4. Summary

Bibliography

Climate and Climate System:

• McGuffie K. and A. Henderson-Sellers, 2005: A Climate Modelling Primer

• Washington W. and C. Parkinson, (1986) 2005: An Introduction to 3-D Climate Modelling

• Goosse H. et al., 2009: Introduction to climate dynamics and climate modelling

Climate Change:

• Weart S., 2003: The Discovery of Global Warming

• IPCC-AR4: Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.), 2007:

Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change,Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change,

2007, Cambridge University Press, available at: www.ipcc.ch

• IPCC-AR5: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment

Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J.

Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and

New York, NY, USA, 1535 pp. www.ipcc.ch/report/ar5

Climate Change in the Mediterranean region:

• Regional Assessment of Climate Change in the Mediterranean, A. Navarra, L.Tubiana (eds.), 2013, Springer, Dordrecht,

The Netherlands.

• Planton S., and co-authors, 2012: The Climate of the Mediterranean Region in Future Climate Projections. P. Lionello

(Editor), Elsevier, ISBN: 978-0-12-416042-2, pp 449-496.

• Gualdi S. and Co-authors, 2013: The CIRCE simulations: a new set of regional climate change projections performed

with a realistic representation of the Mediterranean Sea. Bull. Amer. Meteo. Soc., 94, 65-81

Outline

Part 1: Climate change impacts in the Mediterranean region


2. Overview of the tools we use to investigate the climate

change and its impacts: climate models and scenario

simulations


signal in the Mediterranean area:



4. Summary

The scientific basis of climate change

Climate Change: direct observations

IPCC WG1-AR4, FAQ 3.1, Figure 1

50 0.128±±±±0.026

100 0.074±±±±0.018

Period Rate

Years °°°°/decade

Climate Change: direct observations


Multiple complementary

indicators of a changing

global climate

Each line represents an

independently derived

estimate of change in the

climate element.

IPCC WG1-AR5

precipitationevaporation


THE CLIMATE SYSTEM

AtmosphereAtmosphere

precipitationevaporation

Ocean

Biosphere

Soil humidity

Run-off

criosphere

Land


Mechanisms of Climate Change

EXTERNAL CAUSES

� Solar activity

� Meteorite

� Terrestrial orbit ANTHROPIC CAUSES

THE CLIMATE SYSTEM

INTERNAL (NATURAL) CAUSES

� Feedbacks

� Volcanic eruptions

� Continental drifts

ANTHROPIC CAUSES

� Greenhouse gases emissions

� Aerosol-Clouds

� Land use

The Climate Engine


THE CLIMATE SYSTEM

Solar

radiation

GREEN-HOUSE EFFECTT= -18 °°°°C

T= +15 °°°°C

Terrestrial

radiation


• 78% Nitrogen.

•

The Atmospheric Composition

THE CLIMATE SYSTEM

.

• 21% Oxygen

• 1% Argon.

• + traces (H2O vapour, CO2, CH4, O3, …)


CO2

Main greenhouse gases (GHGs) concentration during the last 600,000 years

Glacial-Interglacial Ice Core Data

CH4

presentpast

The atmospheric concentration of CO2 (and CH4) at the end of the 20th century exceeds by

far the natural range of the last 650,000 yearsIPCC-AR4, Figure TS.1


Now we know that:

� the greenhouse gases (CO2, …) concentration in the Earth’s

atmosphere is changing at an unprecedented rate and has reached

� the greenhouse gases (CO2, …) play an important role in the

regulation of the Earth’s energy balance (temperature)

How can we investigate and understand (quantitatively)

the effects of increased concentration of the atmospheric

greenhouse gases on the Earth’s climate?

atmosphere is changing at an unprecedented rate and has reached

unprecedented values (at least wrt past 600 Kyears)

Climate Models and Simulations

CLIMATE SYSTEMpowerful

super-computer

MODELLING THE CLIMATE SYSTEM

Scientists apply that knowledge to a scaled-down, computer

simulation of the planet: a global climate model

criospherecriosphere

OCEAN

Biosphere

LAND

Run-off

Atmosphere

precipitation

evaporation

super-computer

Outline





simulations





4. Summary

CLIMATE SYSTEM

Atmosphere

precipitation

evaporation



criosphercriospher

ee

OCEAN

Biosphere

LAND

Run-off

precipitation

Modelers represent Earth’s surface and Atmosphere as

A virtual world made up of interacting, three-dimensional boxes



Mathematical equations that represent the

physical characteristics and processes are entered for each box



Equations are converted to

computer code and climate variables are set


HOW GOOD ARE CLIMATE MODELS TO REPRODUCE THE

OBSERVED MEAN CLIMATE?

Evolution of the mean surface temperature OBSERVED and SIMULATED

Deviation with respect to the 1901-1950 mean

IPCC-AR4 FAQ 8.1, Figure 1

Simulation of the 20th century with the

Climate models forced with:.

� all forcings (natural+anthropogenic).

� only natural (solar+volcanic) forcings

Understanding and Attribution of Climate Change


All forcings

Observed changes are:.

� consistent with expected responses to all

forcings.

� inconsistent with alternative explanations

(i.e. solar forcing only)

Modified from IPCC WG1-AR5

Natural only:

Solar+volcanic

CMIP3

CMIP5

observations

Models reproduce reasonably well the main features of the observed

current climate and its basic mechanisms of change in the recent past

Thus, we can use them to get insights about possible future climate

changes due to human activities (greenhouse gases, land use change …)


Climate change projections are done by means of SCENARIOSClimate change projections are done by means of SCENARIOS

A scenario is a description of a hypothetical future development of the

Earth’s societies and economies.

As an outcome of a scenario we have emissions (atmospheric

concentrations) of greenhouse gases, aerosols, land use change, etc …

that can be given as an input to our climate models to produce future

climate simulations

CO2 EMISSIONS CO2 CONCENTRATIONS

IPCC scenarios of greenhouse gases emissions and

concentrations (used to perform the IPCC climate projections)

Climate Change Projections


IPCC scenarios of greenhouse gases emissions and

concentrations (used to perform the IPCC climate projections)

EMISSIONS

IPCC WG1-AR5

CONCENTRATIONS

GLOBAL MEAN SURFACE TEMPERATURE CHANGE

FOR THE DIFFERENT SCENARIOS


The International Climate modelling community has completed a new set of global climate projections (CMIP5)

using new GCMs and new emission pathways. These are referred to as Representative Concentration Pathways

(RCPs) and complement the earlier SRES scenarios. CMIP5 will be the primary modelling input to the IPCC AR5

report (CMIP3 + SRES was the main input to IPCC AR4)

Knutti & Janek 2012

AR4 (2007) AR5 (2013)


Annual mean surface air temperature changecompared to the 1986-2005 reference period

RCP8.5 2045-2065 RCP8.5 2081-2100



2046-2065 DJF 2081-2100 DJF

Seasonal mean Precipitation change (RCP8.5)compared to the 1986-2005 reference period


2046-2065 JJA 2081-2100 JJA


Relative Sea-level change 2081-2100compared to the 1986-2005 reference period



GLOBAL MEAN SURFACE

TEMPERATURE CHANGERELATIVE IMPORTANCE OF

DIFFERENT UNCERTAINTIES

Knutti & Janek 2012 Modified from IPCC WG1-AR5

Outline





simulations





1. Summary

State of the art coupled models are generally inadequate to

resolve the dynamical features of the Euro-Mediterranean region

Orography, Land-Sea mask and Mediterranean Sea bathymetry as represented

in a “standard IPCC model” with horizontal resolution of ~300 Km

~300 Km

Climate Change Projections in the Mediterranean region

m

1°

m

In the framework of the CIRCE EU Project: new high-res models for the

Mediterranean basin and new climate change projections for the region

EVALUATING THE H G


CIRCEClimate Change and Impact Research: The Mediterranean Environment

EVALUATING THE H G

IMPACTS OF CLIMATE E

CHANGE IN THE EHT

MEDITERRANEAN REGION

health tourism energy demand human migration

Need to perform new and more advanced climate

simulations specific for the Mediterranean Region

1. Better resolved small-scale feature of the basin (orography land-sea contrast)

CMIP3 CIRCE


2. Improved representation of the air-sea feedbacks

• Improve the representation of the

small-scale processes and features of

the observed climate


Need to perform new and more advanced climate

simulations specific for the Mediterranean Region

the observed climate

• Improve the surface fluxes over the

Mediterranean Sea

• Improve the representation of the

Mediterranean-Atlantic interaction

(Gibraltar)

The CIRCE modelsModel Atmosphere

component

Global Ocean

Component

Med. Sea

Component

Gibraltar and lateral

Boundary Conditions

Rivers and Black Sea

CMCC(INGV)

Scoccimarro

et al. 2011

ECHAM5

80km L31

OPA8.2-

ORCA2

~2°x2°(0.5°)

L31

NEMO-MFS

1/16° L71Oddo et al 2009

Fluxes exchanged between

global ocean and Med Sea.

Med. outflow distributed over

upper 300m in global ocean

grid point near Gibraltar

TRIP river scheme (Nile

runoff corrected to

observations after 1968).

Black Sea input from the

E-P-R flux (Oki and Sud

1998)

LMD(IPSL)

LMDZ glob +

LMDZ reg

OPA9-

ORCA2

NEMO-MED

1/8° L43

Tracer profile and fluxes

exchanged using Cross-Land

Climatological river

discharge (Ludwig et al.


(IPSL)

Zou et al.

2010

LMDZ reg

300km L19 +

30km L19

ORCA2

~2°x2°(0.5°)

L31

1/8° L43Beuvier et al. 2010


Advection parametrization

and buffer zone


2009)

CNRM(MF-CNRM)

Somot et al.

2008

ARPEGE-Climate

T159 L31Stretched model:

50km in Med. Area

OPA9-

ORCA2

~2°x2°(0.5°)

L31

NEMO-MED

1/8° L43Beuvier et al. 2010

Tracer profile and fluxes


Advection parametrization

and buffer zone.

Climatological river


2009)

PROTHEUS(ENEA)

Artale et al.

2010

REG-CM3

30km L19 /

MIT-gcm

1/8° L42Sannino et al. 2009

Atlantic buffer zone.

Lateral boundaries from

ECHAM5/MPI-OM (Giorgetta

et al. 2006)

IRIS river scheme.

Instantaneous runoff to

the river mouth. . Black

Sea input from the E-P-R

bias corrected.

MPI(MPI-HH)

Elizalde 2011

REMO

25km L31 /

MPI-OM

9km L29Elizalde et al. 2010

Atlantic buffer zone.

Lateral boundaries from

CMCC (Scoccimarro et al.

Interactive hydrological

model and Black Sea

model (Hagemann and

Projected 2-m Temperature trend(°C/year)*100

T2m trend 2001-2050 DJF Precip. trend 2001-2050 DJF


T2m trend 2001-2050 JJA Precip. trend 2001-2050 JJA

shading 95% significant

deviation with respect to the 1961-1990 reference period

Evolution of the Mediterranean Sea surface Heat Budget

total Heat flux10

8

shortwave heat flux longwave heat flux

projected surface heat flux increases (≈0.6 W/m2 per decade) � LESS SURFACE HEAT LOSS


6

4

2

0

-2

-4

-6

-8

W/m

2

1950 1970 1990 2010 2030 2050

sensible heat fluxlatent heat flux

Evolution of the Mediterranean Sea Surface Temperature anomalies


CIRCE MODELS

CIRCE ENS MEAN

CMIP3 ENS MEAN


During the 2001-2050 period (A1B scenario) the CIRCE models produce a warming trend of about 0.34 °C/decade

CMIP3 ENS MEAN

Evaporation and E-P trends 2001-

2050Evap trend 2001-2050 DJF E-P trend 2001-2050 DJF

(mm/day)

year100*


Evap trend 2001-2050 JJA E-P trend 2001-2050 JJA

0.3

0.2


Evolution of the Mediterranean Sea surface Water Budget (E-P-R)

surface water flux

precipitation flux evaporation flux

projected surface water budget decreases (≈0.07 mm/day per decade) � MORE EVAPORATIVE


0.2

0.1

0.0

-0.1

-0.2

-0.3

-0.4

-0.5

-0.6

mm

/da

y

1950 1970 1990 2010 2030 2050

runoff flux Black Sea flux

Factors affecting the Mediterranean sea level

1. density of the water column (steric effect)

Thermosteric: thermal expansion or contraction

Halosteric: changes in salinity

Climate Change Projections: the sea-level problem

3. atmospheric pressure and large-scale atmospheric circulationregional effect (globally zero)relatively small compared to steric and water mass components

2. water mass content of the basinmass variations mostly due to the global-scale changes associated

with the continental ice melting (Greenland, West Antarctica)

Mediterranean sea level has been rising at a lower rate than global sea

level during the last decades

Observed sea-level trend in the Mediterranean basin

mm/year

In the past decades, Mediterranean sea level has been rising at a lower rate than global ocean


level during the last decades

• increase in the atmospheric pressure over the region

• slight increase of salinity, attributed to the increase in the deficit of the

freshwater budget

Credits: modified from Tsimplis (MedClivar, 2011)

SEA LEVEL CHANGE due to the STERIC EFFECT

computed from the CIRCE models

During the 2001-2050 period (A1B scenario) the CIRCE models produce asteric SLR trend of about ≈ 0.29 cm/yr


CIRCE MODELS

CIRCE ENS MEAN


Interestingly, reduced spread compared to Marcos and Tsimplis(2008)


Sea level rise of the Global oceanrelative to 1986–2005 for the four RCP scenarios

Atlantic Ocean Mediterranean Sea

Relatively fresh Atlantic water

How long and to what extent can Mediterranean sea level

continue rising at a lower rate than global mean sea level ?


Gibraltar

Relatively salty Mediterranean water

Credits: modified from Tsimplis 2011

Warming of the climate system is unequivocal, as it is now evident from observations

Models appear to reproduce reasonably well the main features of the observed current

climate and its basic mechanisms of change in the recent past. At the moment they represent

Most of the observed warming since the mid-20th century is very likely due to the

observed increase in anthropogenic greenhouse gas concentrations

Summary and Conclusions

Global

climate and its basic mechanisms of change in the recent past. At the moment they represent

the most suitable and valuable tool to explore the possible future climate scenarios

Continued greenhouse gas emissions would cause further warming and induce many

changes in the global climate system during the 21st century

The 21st century climate change would very likely be larger than those observed during

the 20th century with substantial impacts on human societies and ecosystems

Climate change is occurring and is not avoidable, so now the challenge is to manage what is

unavoidable (adaptation) and avoid what we can not manage (mitigation)

Climate change projections performed with high-resolution models of the Mediterranean Sea

indicate that remarkable changes in the regional climate might occur already in the early few

decades of the scenario

A substantial warming (≈1.5°°°°C in winter and ≈2°°°°C in summer) and a significant decrease of

precipitation (≈-5%) might affect the region in the 2021-2050 period compared to the reference

period (1961-1990), in an A1B emission scenario.

Summary and Conclusions

Mediterranean

period (1961-1990), in an A1B emission scenario.

The Mediterranean Sea surface net heat loss decreases (-0.6 W/m2 per decade) in the projected

period, leading to a weaker cooling of the basin by the atmosphere

The projected surface water budget increases (≈0.25 mm/day), leading the Mediterranean Sea

to loose more water through its surface than in the past.

The projections show a 2021-2050 mean steric sea-level rise between +7 and +12 cm compared

to the period of reference. At the end of the century this value might be of about 20 cm, to

which we should add the sea-level rise due to land ice melting (Greenland and Antarctica)

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