Massimo Frezzottimassimo.frezzotti@enea.it

ENEA, Roma, Italy

Programma Nazionale di Ricerche in Antartide

www.taldice.org

Il ghiaccio e i cambiamenti climatici

Associazione Galileo 2001

Convegno

Clima, Energia, Società

Roma, 13 e 14, ottobre 2009

1. I ghiacci polari come archivio naturale della

storia del clima nell’ultimo milione di anni.

Sommario

2. I ghiacci continentali ed il livello dei mari

3. Il ghiaccio marino componente

fondamentale nell'equilibrio

climatico/ambientale

Paleoclimatology: Natural Archives

0 200 400 600 800 1000 1200 14001600 1800 2000

Moberg et al. (2005)

PEG

PCM

>35 Myr

CO2 1250±250 ppm

Sea level +73 m

around 32 Myr

CO2 500±150 ppm

Sea level +45±5 m

Pre-industraila Era

CO2 280 ppm

Sea level 0 m

LGM 21 kyr

CO2 185 ppm

Sea level -130±10 m

PALEO-GLACIOLOGY: ICE, CO2 & TEMPERATURE

t Alley et al., 2005

Relation between estimated atmospheric CO2 and the ice contribution to eustatic sea level indicated

by geological archives and referenced to modern (pre-Industrial Era) conditions.

Greenhouse gases – the long-term perspective

•Higher greenhouse gas concentrations during warm climate periods.

•Seasonal and latitudinal variations in insolation due to changes in Earth's orbit.

•Strength of major warming implies amplification through albedo and greenhouse gas

changes

Jouzel et al., 2007, Petit et al., 1999, Lüthi et al. , 2008, Loulergue et al., 2008, Schilt et al., 2009

Dome C, Vostok

t

!D

CO2

CH4

tCO2 concentrations lagged Antarctic warming from 800±200 to 600±400 years

No doubt on the strong coupling of CO2 and temperature

CO2 and albedo key amplification factor of the large temperature variations of glacial-interglacial cycles

Monin et al., 2001; Fisher et al., 2005; Siegenthaler et al., 2005

CO2 , CH4 & TEMPERATURE

Siegenthaler et al, 2005 ; Spahni et al., 2005 ; Lüthi et al., 2008 ; Loulergue et al., 2008

!"#$%&'()*&$

!"#$%&'()*&$

!"#$%&'()*&$

+(,-(.300

170

750

350

MBEMBE

t

CO2 , CH4 & TEMPERATURE

•No analog of present-day values during the last 800 kyr

•CO2 (and CH4 , except MIS 19) show lower interglacial concentrations before 400 kyr BP

•CO2 dominated by Southern Ocean (mixing, iron fertilization)

Siegenthaler et al, 2005 ; Spahni et al., 2005 ; Lüthi et al., 2008 ; Loulergue et al., 2008

•No analog of present-day values during the last 800 kyr

•CO2 (and CH4 , except MIS 19) show lower interglacial concentrations before 400 kyr BP

•CO2 dominated by Southern Ocean (mixing, iron fertilization)

!"#$%&'()*&$

!"#$%&'()*&$

!"#$%&'()*&$

+(,-(.

!!COCO22

105 ppmv105 ppmv

(280-385)(280-385)

+37%+37%

300

170

CH4 1750 ppbv

+135%

750

350

!!T ~ 12 °CT ~ 12 °C

!!COCO22 130 ppmv 130 ppmv

MBEMBE

!!CHCH44 400 400 ppbvppbv

t

CO2 , CH4 & TEMPERATURE

•Greatest CO2 preindustrial rate is 3.6 ppm/century from 14.6 kyr BP to 14.3 kyr BP

•20 times smaller than the average rate of 71 ppm/century during 20th century.

CO2 Amplitude and period variability in natural and anthropogenic condition

Joos & Spahni, 2008

Sequence of rapid events during last deglaciation (Greenland ice core)

Low latitude trigger, (dust changes first) ; deuterium excess transition in 1-3 years

Steffensen et al, 2008

t

t

HE1

B/A

B/A

YD

YD

HO

RAPID EVENT IN

GREENLAND

-45

-41

-37

-33

-450

-430

-410

350

500

650

800

10000 20000 30000 40000 50000 60000

-52

-49

-46

-43

-52

-48

-44

EDML Tsu

rf

[ °C

]

!18

Oco

rr

[ °/ °

°]

NGRIP age [yr BP]

CH4

[p

pb

v]

ACR

AIM 8

NorthGRIP

Greenland CH4

composite

EDML

DO1

23 4 5 6 7

DO8

910 11

DO12

EDC

!18

O [ °

/ °°]

!Dc

orr

[ °

/ °°]

AIM 12AIM 1

AIM 2

AIM 45 6

7

39

10 11

4.1

4.1

H1

H2 H3 H4 H5

0.0

1.0

2.0

3.0

12

11

10

9

8

7

65

4.1

4

3

500 1000 1500 2000

NGRIP stadial duration [yr]

ED

ML !

Tsu

r f [°

C]

Every rapid warming in Greenland (D/O) has a counterpart in Antarctica (AIM)

Antarctica warms up when Greenland is cold and vice versa

Antarctica (AIM) temperature amplitude linearly related to duration of subsequent

D/O event

EPICA Community Members, 2006

t

Greenland

Antarctica

BIPOLAR

SEESAW

Stocker, 2003

!"##$%&$'

($)&"*)+*&

Sud Nord

BIPOLAR SEESAWoutgoing longwave radiation

outgoing longwave radiation

ne

t ra

dia

tio

n

t

McCarty Glacier, Alaska

1932 2003

Gurglerferner (Austria, Oetztal)

Similaun Glacier, Ozti mummy, 5350 yr BP

1993

2000

Kilimangiaro, Africa

Upsala Glacier, Argentina, Patagonia

CLIMATE SIGNAL FROM 169 GLACIER RECORDS

Oerlemans, 2005

t

ca 4000 km

ICE DISCHARGE

110±70 Gt/yr in 1960s

near balance in 1970s–1980s

97±47 Gt/yr in 1996

267±38 Gt/yr in 2007

5.00E+06

1.00E+07

1.50E+07

2.00E+07

2.50E+07

3.00E+07

1978 1983 1988 1993 1998 2003 2008

Year

Total Melt AreaApril - October

20021998

1995

1991

1992

1996

2005

1987

1983

2007

•Area of summer melting is

increasing

•Melt water rapidly migrates to the ice

sheet base and enhances basal

sliding and accelerating ice discharge

•Increasing summer temperatures,

more melt water, and greater ice

acceleration.

GREENLAND

Zwally et al., 2002; Rignot et al., 2008

t

(de Angelis & Skvarca, 2003; Domack et al., 2005; Prichard et al., 2009) Larsen B Feb 2002

Rapid disintegration or collapse of

Antarctic Peninsula and Amundsen

Sea ice shelves due to atmospheric

and ocean warming.

Larsen B ice shelf collapsed in 3

weeks after 10,000 years of

existence.

Temperature over the Antarctic Peninsula

has risen 2.5 °C in the past 50 yr (Turner et

al., 2005).

Many glaciers of Peninsula and Amundsen

Sea are accelerating (doubling) and thinning

(up to 9 m yr-1)

ANTARCTICA

ICE SHEET MASS BALANCE AND SEA LEVEL RISE

Allison et al., 2009

GREENLAND ANTARCTICA

Church et al., 2004, 2006

Holgate and Woodworth, 2004

19th AND 20th CENTURY SEA LEVEL RISE

Satellite altimetry

Bindoff et al., 2007

3.2 ± 0.3 mm yr-1

1.8 ± 0.3 mm yr-1

Current sea level rise has occurred at a mean rate of 1.8 ± 0.3 mm per year for the past

century, and more recently at rates estimated to 3.2 ± 0.3 mm per year. Sea level

acceleration up to the present appears to have started at the end of the 18th century

(Jevrejeva et al., 2008).

SEA LEVEL RISE SINCE LAST GLACIAL MAXIMUM

last century

SLR 1.8 mm yr -1

Today

SLR 3.2 mm yr -1

10 times

current rate MWP1A

SLR 40 mm yr -1

from roman time to pre-industrial

SLR >0.1 mm yr -1

Last Glacial Maximum eustatic sea level -125±5 m, twice the present volume of

Greenland and Antarctic Ice Sheets.

Sea level rise about 20 m in 500 yr (40 mm yr -1) during MWP1A caused by ice-sheet

instability

Sea level rise slowly (0.13±0.09 m or 0.06 mm yr -1) from 2000 years ago until 19th

century (Lambeck et al., 2004; Clarke et al., 2009).

t

max

max

min

min

North Pole

Sea ice extent: max 12 M km2

min 4 M km2

Ice sheet: Greenland

South Pole

Sea ice extent: max 20 M km2

min 4 M km2

Ice sheet: Antarctica

Arctic Antarctica

(modified from Stroeve et al., 2007)

ARCTIC SEA ICE EXTENSION: IPCC simulation vs observations

20072008

2009

Grazie per la vostra attenzionemassimo.frezzotti@enea.it