Arctic Climate Variability in Arctic Climate Variability in the Context of Global Changethe Context of Global Change

Ola M. Johannessen, Lennart Bengtsson,

Leonid Bobylev, Svetlana I. Kuzmina, Elena Shalina

Arctic from spaceArctic from space

VARIATIONS OF THE EARTH'S SURFACE TEMPERATURE FOR THE PAST 1000 YEARS

TEMPERATURE CHANGES AS A RESPONSE TO GREENHOUSE GAS LEVELS INCREASING

ANNUAL MEAN TEMPERATURE IS SHOWN

THE RESULTS WERE AVERAGED FROM 19 CLIMATE MODELS USED TO PREDICT FUTURE CLIMATE BASED ON A 1% PER YEAR INCREASE IN GREENHOUSE GAS LEVELS.

THE TEMPERATURE CHANGES ARE EXPECTED TO BE GREATER IN THE ARCTIC THAN AT LOWER LATITUDES.

ZONALLY AVERAGED ANNUAL MEAN TEMPERATURE ANOMALIES

observations

TIME EVOLUTION OF CHANGES IN ZONALLY AVERAGED ANNUAL MEAN NEAR SURFACE TEMPERATURE

for

a) observationsb) ECHAM4/OPYC GHG runc) ECHAM4/OPYC GSD rund) ECHAM4/OPYC CONTROL run

Monitoring ice concentration from microwave satellites

water

land

100%

90%

80%

70%

60%

50%

40%

30%

15%

water

land

TOTAL ICE COVER = MULTI-YEAR ICE + FIRST-YEAR ICE

Arctic monthly total sea ice area : 1978-2002

14% decrease in September14% decrease in September5% decrease in March5% decrease in March

record-low summer ice coverage 6*record-low summer ice coverage 6*10106 6 kmkm2 2

in September 2002in September 2002

Arctic total sea ice area anomalies: 1978-2002

1978-2002 – Trend: ~8x101978-2002 – Trend: ~8x1055 km km22 (~-3% per decade) (~-3% per decade)

-10

-8

-6

-4

-2

0

2

4

6

8

10

12

19

78

19

80

19

82

19

84

19

86

19

88

19

90

19

92

19

94

19

96

19

98

20

00

20

02

Year

An

om

aly

(m

illio

n k

m2 )

Microwave-derived multi-year ice area

The results are obtained for five winter months (Nov-March). The results are obtained for five winter months (Nov-March). The negative trend is about 8.8% per decade, which is in The negative trend is about 8.8% per decade, which is in good agreement with the results of J.Comiso: good agreement with the results of J.Comiso: 7.1% per decade for MY ice extent and 9.2% per decade for 7.1% per decade for MY ice extent and 9.2% per decade for MY ice areaMY ice area

Mean ice concentrationfor (a) winter and (b) summer,

Linear trendsfor (c) winter50% decrease in the 50% decrease in the Barents and Greenland Barents and Greenland seasseas

and (d) summer

> 50% decrease> 50% decrease in in Beaufort and Chukchi Beaufort and Chukchi seas, seas, 30-50% in Siberaian 30-50% in Siberaian marginal seas.marginal seas.

March September

Satellite-based sea-ice concentration, 1978-2002:

Annual sea-ice extent derived from Russian dataset (red), Walsh dataset (green) and (70-90°N) surface air temperature (black)

Annual sea-ice extent and surface air temperature

r ~ 0.6

Ice thickness data

Arctic winter multi-year ice areavs. estimated ice thickness

SMMR and SSM/I-derived Arctic winter MY ice area, SMMR and SSM/I-derived Arctic winter MY ice area, and basin-wide ice thickness estimated from Russian and basin-wide ice thickness estimated from Russian drifting drifting North PoleNorth Pole measurements of ice surface measurements of ice surface oscillations, 1978-1990. oscillations, 1978-1990. Correlation coefficient (Correlation coefficient (rr) ~ 0.88.) ~ 0.88.

The modeled scenarios include a control run (CRL), changes in greenhouse gases (GHG) and greenhouse gases plus sulfate aerosols (GSD).

185 0 190 0 195 0 2 0 0 0 2 0 5 0 2 10 0 2 15 0Y ea r

0

2

4

6

8

10

12

14

16

Ice

ext

ent

(m

illio

n sq

uare

km

)

G H G

G S D

C R L

O B S

O B S

OBSERVED ANDECHAM4-MODELLEDNORTHERN HEMISPHERE SEA-ICE EXTENT IN MARCH (upper) AND SEPTEMBER (lower)

2005 Summer 2085

80% decrease

Climate model simulation of ice concentration due

to CO2 doubling

Ice concentration

2005 2085

20% decrease

Winter

Climate model simulation of ice concentration due to CO2 doubling

Ice concentration

Temperature change ANIMATION

Greenland Ice Sheet elevation

changes Elevation changes for 1992 - 2003 derived from merged ERS -1 and ERS -2 measurements

Result: 5.4 ± 0.3 cm/year

Elevation,km

dh/dt,cm/year

Area,103 km2

<1.5 -2.0 155.11.5-2 5.6 228.22-2.5 7.0 398.92.5-3 6.4 458.3

>3 5.5 140.3Whole Greenland 5.4 1380.7

Elevation changes averaged over high- and low-elevation areas of Greenland

1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003Year

-50

-40

-30

-20

-10

0

10

20

30

40

50

Ele

vati

on

ch

ang

e, c

m

> 1500 m

< 1500 m

Elevation Elevation growth is growth is indicated indicated over most of over most of interior interior regions, regions, while over while over margin margin areas ice areas ice sheet sheet thinning is thinning is revealedrevealed

Visible satellite snow Visible satellite snow charts developed by charts developed by David Robinson team David Robinson team show that negative show that negative anomalies of snow anomalies of snow extent have extent have dominated since 1987dominated since 1987

THERE HAVE BEEN DECREASE OF ABOUT 10% IN THE EXTENT OF SNOW COVER SINCE THE LATE 1960s

ANOMALIES OF MONTHLY SNOW COVEROVER THE NORTHERN HEMISPHERE LANDS

(INCLUDING GREENLAND)between November 1966 and January 2005

snow cover

COMPOSITE OF OBSERVED VARIABILITYIN THE ARCTIC OCEAN-CLIMATE SYSTEM SINCE 1950

(A)(A) NORTH ATLANTIC

OSCILLATION INDEX,

(B)(B) ANOMALIES IN SURFACE AIR

TEMPERATURE

(C)(C) ARCTIC SEA ICE EXTENT

(D)(D) RUNOFF INTO THE ARCTIC

OCEAN FROM THE MAJOR

SIBERIAN RIVERS

(E)(E) GREENLAND SEA DEEP-

WATER (GSDW) TEMPERATURE

AT 2000M DEPTH

- 2 TO 4 % INCREASE IN THE FREQUENCY OF HEAVY PRECIPITATION EVENTSIN THE MID- AND HIGH LATITUDES OF THE NORTHERN HEMISPHERE

- REDUCTION IN THE FREQUENCY OF EXTREME LOW TEMPERATURES SINCE 1950 WITH A SMALLER INCREASE IN THE FREQUENCY OF EXTREME HIGH TEMPERATURES

PERCENT OF GLOBAL AREA SAMPLED PERCENT OF GLOBAL AREA SAMPLED SHOWING SIGNIFICANT CHANGE IN SHOWING SIGNIFICANT CHANGE IN EXTREME INDICATORSEXTREME INDICATORSEXTREME

EVENTS Significant POSITIVE change Precipitation Temperature

Significant NEGATIVE change Precipitation Temperature

Focus Natural climate variability and greenhouse

warming in the Arctic and sub-Arctic regions.

Phenomena• Greenhouse warming - centuries• NAM - Northern hemisphere

Annular Mode (NAO/AO oscillations) - decadal

• AMO (Atlantic Multi-decadal Oscillations)

Positive NAO indexNegative NAO

index

Natural variability:the North Atlantic Oscillation

dry

wetdry

wet

1860 1880 1900 1920 1940 1960 1980 2000

0.3

0.2

0.1

0

-0.3

-0.1

-0.2

THE HISTORY OF AMO INDEX SHOWS THAT POSITIVE AND NEGATIVE PHASES TYPICALLY LAST FOR 20 TO 40 YEARS.

SINCE 1994, THE AMO INDEX HAS BEEN POSITIVE

ATLANTIC MULTIDECADAL OSCILLATION (AMO) INDEX

1860 1880 1900 1920 1940 1960 1980 2000

0.3

0.2

0.1

0

-0.3

-0.1

-0.2

AMO

Conclusions

• The global average surface temperature has increasedtemperature has increased over the 20th century by about 0.570.57ooCC, the temperature of the Polar region (60-90oN) has increased by 1.31.3ooCC

• The increase in temperature in the 20th century has been the largest of any century during the past 1,000 years, the 1990th was the warmest decade1990th was the warmest decade

• The sea-ice extentsea-ice extent over the Northern Hemisphere showed a decrease of about 3% per decade3% per decade, though MY MY (perennial) ice(perennial) ice declined at a rate of about 9%9% per decade

• We also observe a decrease of snow coverdecrease of snow cover of about 2%2% per decade and an increase in precipitation and increase in frequency of heavy precipitation events

PRONOUNCED CHANGES ON DECADAL AND MULTI-DECADAL TIME SCALES HAVE TAKEN PLACE IN THE ARCTIC OVER THE LAST CENTURY

ANTHROPOGENIC CLIMATE CHANGE WILL PERSIST FOR MANY CENTURIES

•Even several centuries after emissionsseveral centuries after emissions of long-lived greenhouse gases, the amount remaining in the remaining in the atmosphere is 20 to 30% of the total emittedatmosphere is 20 to 30% of the total emitted

•Global mean surface temperature will continue to Global mean surface temperature will continue to increase and sea level will continue to riseincrease and sea level will continue to rise due to thermal expansion for hundreds of years after for hundreds of years after stabilisationstabilisation of greenhouse gas concentrations

•Ice sheets will continue to reactIce sheets will continue to react to climate warming and contribute to sea level rise for thousands of yearsfor thousands of years after climate has been stabilised

Possible consequences of less ice in the Arctic

• More CO2 uptake in the Arctic Ocean

• Sea transport more feasible

• Easier to explore and produce oil and gas

• Changes in fisheries and biodiversity

• Increased freshwater melt reduces deep water formation, with potential reduction of the Gulf Stream into the Nordic Seas