Download Climate system and impacts in the Mediterranean Basin

Climate system and impacts in the Mediterranean Basin
Silvio Gualdi
Centro Euro-Mediterraneo sui Cambiamenti Climatici,
Istituto Nazionale di Geofisica e Vulcanologia
Outline
Scope: understanding the dynamic of climate change
and its physical impacts in the Mediterranean basin
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
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,
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
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
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
The scientific basis of climate change
Climate Change: direct observations
Period
Rate
50 0.128±
±0.026
100 0.074±
±0.018
Years °/decade
IPCC WG1-AR4, FAQ 3.1, Figure 1
The scientific basis of climate change
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
The scientific basis of climate change
THE CLIMATE SYSTEM
Atmosphere
evaporation
precipitation
criosphere
Biosphere
Run-off
Ocean
Land
Soil humidity
The scientific basis of climate change
THE CLIMATE SYSTEM
Mechanisms of Climate Change
EXTERNAL CAUSES
Solar activity
Meteorite
Terrestrial orbit
INTERNAL (NATURAL) CAUSES
Feedbacks
Volcanic eruptions
Continental drifts
ANTHROPIC CAUSES
Greenhouse gases emissions
Aerosol-Clouds
Land use
The scientific basis of climate change
THE CLIMATE SYSTEM
The Climate Engine
Solar
radiation
Terrestrial
radiation
GREEN-HOUSE EFFECT
T= -18 °C
T= +15 °C
The scientific basis of climate change
THE CLIMATE SYSTEM
The Atmospheric Composition
• 78% Nitrogen
• 21% Oxygen
.
• 1% Argon
• + traces (H O vapour, CO , CH , O , …)
.
2
2
4
3
The scientific basis of climate change
Main greenhouse gases (GHGs) concentration during the last 600,000 years
Glacial-Interglacial Ice Core Data
CO2
CH4
past
present
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 years
IPCC-AR4, Figure TS.1
The scientific basis of climate change
Now we know that:
the greenhouse gases (CO2, …) play an important role in the
regulation of the Earth’s energy balance (temperature)
the greenhouse gases (CO2, …) concentration in the Earth’s
atmosphere is changing at an unprecedented rate and has reached
unprecedented values (at least wrt past 600 Kyears)
How can we investigate and understand (quantitatively)
the effects of increased concentration of the atmospheric
greenhouse gases on the Earth’s climate?
Climate Models and Simulations
MODELLING THE CLIMATE SYSTEM
Scientists apply that knowledge to a scaled-down, computer
simulation of the planet: a global climate model
CLIMATE SYSTEM
Atmosphere
evaporation
precipitation
criosphere
Run-off
OCEAN
Biosphere
LAND
powerful
super-computer
Outline
Part 1: Climate change impacts in the Mediterranean region
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
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
Climate Models and Simulations
MODELLING THE CLIMATE SYSTEM
CLIMATE SYSTEM
Atmosphere
evaporation
precipitation
criospher
e
Biosphere
Run-off
OCEAN
LAND
Modelers represent Earth’s surface and Atmosphere as
A virtual world made up of interacting, three-dimensional boxes
Climate Models and Simulations
MODELLING THE CLIMATE SYSTEM
Mathematical equations that represent the
physical characteristics and processes are entered for each box
Climate Models and Simulations
MODELLING THE CLIMATE SYSTEM
Equations are converted to
computer code and climate variables are set
Climate Models and Simulations
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
Climate Models and Simulations
Understanding and Attribution of Climate Change
Simulation of the 20th century with the
Climate models forced with:
All forcings
.
all forcings (natural+anthropogenic)
.
only natural (solar+volcanic) 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
CMIP3
CMIP5
observations
Natural only:
Solar+volcanic
Climate Models and Simulations
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 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
Climate Change Projections
IPCC scenarios of greenhouse gases emissions and
concentrations (used to perform the IPCC climate projections)
CO2 EMISSIONS
CO2 CONCENTRATIONS
Climate Change Projections
IPCC scenarios of greenhouse gases emissions and
concentrations (used to perform the IPCC climate projections)
EMISSIONS
CONCENTRATIONS
IPCC WG1-AR5
Climate Change Projections
GLOBAL MEAN SURFACE TEMPERATURE CHANGE
FOR THE DIFFERENT SCENARIOS
AR4 (2007)
AR5 (2013)
Knutti & Janek 2012
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)
Climate Change Projections
Annual mean surface air temperature change
compared to the 1986-2005 reference period
RCP8.5 2045-2065
Modified from IPCC WG1-AR5
RCP8.5 2081-2100
Climate Change Projections
Seasonal mean Precipitation change (RCP8.5)
compared to the 1986-2005 reference period
2046-2065 DJF
2046-2065 JJA
Modified from IPCC WG1-AR5
2081-2100 DJF
2081-2100 JJA
Climate Change Projections
Relative Sea-level change 2081-2100
compared to the 1986-2005 reference period
Modified from IPCC WG1-AR5
Climate Change Projections
GLOBAL MEAN SURFACE
TEMPERATURE CHANGE
Knutti & Janek 2012
RELATIVE IMPORTANCE OF
DIFFERENT UNCERTAINTIES
Modified from IPCC WG1-AR5
Outline
Part 1: Climate change impacts in the Mediterranean region
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
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
1. Summary
Climate Change Projections in the Mediterranean region
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
1°
m
m
Climate Change Projections in the Mediterranean region
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
IMPACTS OF CLIMATE E
CHANGE IN THE
EHT
MEDITERRANEAN REGION
CIRCE
Climate Change and Impact Research:
The Mediterranean Environment
health
tourism
energy demand
human migration
Climate Change Projections in the Mediterranean region
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
Climate Change Projections in the Mediterranean region
Need to perform new and more advanced climate
simulations specific for the Mediterranean Region
2. Improved representation of the air-sea feedbacks
• Improve the representation of the
small-scale processes and features of
the observed climate
• Improve the surface fluxes over the
Mediterranean Sea
• Improve the representation of the
Mediterranean-Atlantic interaction
(Gibraltar)
Climate Change Projections in the Mediterranean region
The CIRCE models
Model
Atmosphere
component
Global Ocean
Component
Med. Sea
Component
Gibraltar and lateral
Boundary Conditions
Rivers and Black Sea
CMCC
ECHAM5
80km L31
OPA8.2ORCA2
~2°x2°(0.5°)
L31
NEMO-MFS
1/16° L71
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)
Tracer profile and fluxes
exchanged using Cross-Land
Advection parametrization
and buffer zone
Climatological river
discharge (Ludwig et al.
2009)
Tracer profile and fluxes
exchanged using Cross-Land
Advection parametrization
and buffer zone.
Climatological river
discharge (Ludwig 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.
Atlantic buffer zone.
Lateral boundaries from
CMCC (Scoccimarro et al.
Interactive hydrological
model and Black Sea
model (Hagemann and
(INGV)
Scoccimarro
et al. 2011
LMD
(IPSL)
Zou et al.
2010
CNRM
(MF-CNRM)
Somot et al.
2008
PROTHEUS
(ENEA)
Artale et al.
2010
MPI
(MPI-HH)
Elizalde 2011
LMDZ glob +
LMDZ reg
300km L19 +
30km L19
OPA9ORCA2
~2°x2°(0.5°)
L31
ARPEGE-Climate
T159 L31
OPA9ORCA2
~2°x2°(0.5°)
L31
Stretched model:
50km in Med. Area
REG-CM3
30km L19
/
Oddo et al 2009
NEMO-MED
1/8° L43
Beuvier et al. 2010
NEMO-MED
1/8° L43
Beuvier et al. 2010
MIT-gcm
1/8° L42
Sannino et al. 2009
REMO
25km L31
/
MPI-OM
9km L29
Elizalde et al. 2010
Climate Change Projections in the Mediterranean region
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
Climate Change Projections in the Mediterranean region
Evolution of the Mediterranean Sea surface Heat Budget
deviation with respect to the 1961-1990 reference period
projected surface heat flux increases (≈0.6 W/m2 per decade)
shortwave heat flux
LESS SURFACE HEAT LOSS
longwave heat flux
total Heat flux
10
8
6
W/m2
4
2
0
-2
latent heat flux
-4
-6
-8
1950
1970
1990
2010
2030
2050
sensible heat flux
Climate Change Projections in the Mediterranean region
Evolution of the Mediterranean Sea Surface Temperature anomalies
deviation with respect to the 1961-1990 reference period
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
Climate Change Projections in the Mediterranean region
Evaporation and E-P trends 20012050
Evap trend 2001-2050
Evap trend 2001-2050
DJF
JJA
(mm/day)
* 100
year
E-P trend 2001-2050
DJF
E-P trend 2001-2050
JJA
Climate Change Projections in the Mediterranean region
Evolution of the Mediterranean Sea surface Water Budget (E-P-R)
deviation with respect to the 1961-1990 reference period
projected surface water budget decreases (≈0.07 mm/day per decade)
precipitation flux
MORE EVAPORATIVE
evaporation flux
surface water flux
0.3
0.2
0.1
mm/day
0.0
-0.1
-0.2
runoff flux
-0.3
-0.4
-0.5
-0.6
1950
1970
1990
2010
2030
2050
Black Sea flux
Climate Change Projections: the sea-level problem
Factors affecting the Mediterranean sea level
1. density of the water column (steric effect)
Thermosteric: thermal expansion or contraction
Halosteric: changes in salinity
2. water mass content of the basin
mass variations mostly due to the global-scale changes associated
with the continental ice melting (Greenland, West Antarctica)
3. atmospheric pressure and large-scale atmospheric circulation
regional effect (globally zero)
relatively small compared to steric and water mass components
Climate Change Projections: the sea-level problem
Observed sea-level trend in the Mediterranean basin
In the past decades, Mediterranean sea level has been rising at a lower rate than global ocean
mm/year
Mediterranean sea level has been rising at a lower rate than global sea
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)
Climate Change Projections: the sea-level problem
SEA LEVEL CHANGE due to the STERIC EFFECT
computed from the CIRCE models
deviation with respect to the 1961-1990 reference period
CIRCE MODELS
During the 2001-2050 period (A1B
scenario) the CIRCE models produce a
steric SLR trend of about ≈ 0.29 cm/yr
CIRCE ENS MEAN
Interestingly, reduced
spread compared to
Marcos and Tsimplis
(2008)
Climate Change Projections
Sea level rise of the Global ocean
relative to 1986–2005 for the four RCP scenarios
Climate Change Projections: the sea-level problem
How long and to what extent can Mediterranean sea level
continue rising at a lower rate than global mean sea level ?
Relatively fresh Atlantic water
Atlantic Ocean
Mediterranean Sea
Relatively salty Mediterranean water
Gibraltar
Credits: modified from Tsimplis 2011
Summary and Conclusions
Global
Warming of the climate system is unequivocal, as it is now evident from observations
Most of the observed warming since the mid-20th century is very likely due to the
observed increase in anthropogenic greenhouse gas concentrations
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
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)
Summary and Conclusions
Mediterranean
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.
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)
Thanks