Arctic Climate Variability in the Context of Global Change Ola M. Johannessen, Lennart Bengtsson, Leonid Bobylev, Svetlana I. Kuzmina, Elena Shalina

Arctic 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) observations b) ECHAM4/OPYC GHG run c) ECHAM4/OPYC GSD run d) 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 : % decrease in September 5% decrease in March record-low summer ice coverage 6*10 6 km 2 in September 2002

Arctic total sea ice area anomalies: – Trend: ~8x10 5 km 2 (~-3% per decade)

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

Mean ice concentration for (a) winter and (b) summer, Linear trends for (c) winter 50% decrease in the Barents and Greenland seas and (d) summer > 50% decrease in Beaufort and Chukchi seas, 30-50% in Siberaian marginal seas. March September Satellite-based sea-ice concentration, :

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

The modeled scenarios include a control run (CRL), changes in greenhouse gases (GHG) and greenhouse gases plus sulfate aerosols (GSD). OBSERVED AND ECHAM4-MODELLED NORTHERN HEMISPHERE SEA-ICE EXTENT IN MARCH (upper) AND SEPTEMBER (lower)

2005 Summer % decrease Climate model simulation of ice concentration due to CO 2 doubling Ice concentration

% decrease Winter Climate model simulation of ice concentration due to CO 2 doubling Ice concentration

Temperature change ANIMATION

Greenland Ice Sheet elevation changes Elevation changes for derived from merged ERS -1 and ERS -2 measurements Result: 5.4 ± 0.3 cm/year

Elevation changes averaged over high- and low-elevation areas of Greenland Elevation growth is indicated over most of interior regions, while over margin areas ice sheet thinning is revealed

Visible satellite snow charts developed by David Robinson team show that negative anomalies of snow extent have dominated since 1987 THERE HAVE BEEN DECREASE OF ABOUT 10% IN THE EXTENT OF SNOW COVER SINCE THE LATE 1960s ANOMALIES OF MONTHLY SNOW COVER OVER THE NORTHERN HEMISPHERE LANDS (INCLUDING GREENLAND) between November 1966 and January 2005 snow cover

COMPOSITE OF OBSERVED VARIABILITY IN 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 EVENTS IN 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 SHOWING SIGNIFICANT CHANGE IN EXTREME INDICATORS EXTREME 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 wet dry wet

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 AMO

Conclusions temperature has increased 0.57 o C 1.3 o CThe global average surface temperature has increased over the 20th century by about 0.57 o C, the temperature of the Polar region (60-90 o N) has increased by 1.3 o C 1990th was the warmest decadeThe 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 decade sea-ice extent 3% per decadeMY (perennial) ice9%The sea-ice extent over the Northern Hemisphere showed a decrease of about 3% per decade, though MY (perennial) ice declined at a rate of about 9% per decade decrease of snow cover2%We also observe a decrease of snow cover of about 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 several centuries after emissions remaining in the atmosphere is 20 to 30% of the total emittedEven several centuries after emissions of long-lived greenhouse gases, the amount remaining in the atmosphere is 20 to 30% of the total emitted Global mean surface temperature will continue to increase and sea level will continue to rise for hundreds of years after stabilisationGlobal mean surface temperature will continue to increase and sea level will continue to rise due to thermal expansion for hundreds of years after stabilisation of greenhouse gas concentrations Ice sheets will continue to react for thousands of yearsIce sheets will continue to react to climate warming and contribute to sea level rise for thousands of years after climate has been stabilised

Possible consequences of less ice in the Arctic More CO 2 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