North  Atlantic  warming,  disappearing  sea  ice  and  winter  cooling  

 Vladimir  A.  Alexeev,    International  Arctic  Research  Center,  UAF  

with  contributions  from  V.  Ivanov,  R.  Kwok,  I.Ezau,  

J.Cohen,  J.Furtado,  M.Barlow  

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Geography  of  IARC  schools  

  Fairbanks,  AK  

  Toolik  Lake,  AK    Barrow,  AK    McCarthy,  AK  

  Fedorovskoe,  Russia    Arc�c  Ocean    Bellingshausen,  

Antarc�ca  

First summer school, July 2003

Geography  of  IARC  schools  

Map with locations of summer schools (red markers) and (incomplete!) locations of origins of attending students (blue markers).

2010:  King  George  Island,    Bellingshausen  sta�on  

in  collabora�on  with  APECS,    RAE,  RAS,  AWI,  AARI,  IAP  

Scope  

  Focus  on  the  Arc�c  (and  sub-­‐polar  regions)    Climate  system  perspec�ve  

  Depending  on  loca�on,  some�mes  more  focus  on  one  of  the  components    Students  get  involved  in  hands-­‐on  ac�vi�es  

(seeing  is  believing)  

Communications report card, 2013 (Lindsay B)

Part  1:  North  Atlan�c  warming  and    Arc�c  sea  ice  

AMSR2 sea ice conc Sep 2012

Sea ice extent

ocean heat content (delayed freeze up)

Surface-based mechanisms are the most likely contributors to the recent Arctic warming in the summer and fall

Atlantic Water in the Arctic Ocean

Fate of Early 2000s Century Arctic Warm Water Pulse

By I.Polyakov, V.Alexeev, I.Ashik, S. Bacon, A.Beszczynska-Möller, E.Carmack, I.Dmitrenko, L.Fortier, J.-C.Gascard, E.Hansen, J.Hölemann, V.Ivanov, T.Kikuchi, S.Kirillov, Y-D.Lenn, F.A.McLaughlin, J.Piechura, I.Repina, L.Timokhov, W.Walczowski , and R.Woodgate

Bull. Of the Amer Met Soc, 2011

AW significantly contributes to thinning of ice

Polyakov, Timokhov, Alexeev, Ivanov … JPO 2010

Water temperature (ºC) distribution, Laptev Sea, Sep 2013

At cross-slope section along 90ºE)

Thick (up to 50 m) warm surface layer, which almost merges with intermediate Atlantic water layer

http://www.ijis.iarc.uaf.edu

Atlantic  Water  and  arctic  sea  ice.  Winter  

Alexeev et al, 2013, submitted

March 2012

Sea ice, February 2, 2014

http://www.ijis.iarc.uaf.edu

North Atlantic SST

Scoresby, W. 1820. An account of the Arctic regions with a history and description of the Northern whale fishery, (PhD Thesis by S.H.Teigen)

2004 2008

Fraction of multi-year ice

1

0

0 100 200 300 400 500

5 4 3 2 1 0 -1 -2

2004 2006 2008

Alexeev et al, 2013

AW  temperature.  Fram  Strait  and  Svalbard  

March-April 2005

March-April 2006

February-March 2008

Winter  sea  ice  thickness.  Atlantic  sector  

Thinning of ice is local Alexeev et al, 2013

Ice thickness and motion vectors, ICESat Ivanov et al, 2012, Alexeev et al 2013

Meridional wind

DLW (contours) snow anomalies Feb-Mar2008

Ice concentration anomaly

0  

0.2  

0.4  

0.6  

2004   2005   2006   2007   2008  

How much ice does AW melt?

Explains at least 20% of the negative 2004-08 trend (volume-wise)

Alexeev et al, 2013

Part  2:  Is  warming  in  the  Arctic  causing  colder  winters  ?  

Winter temperature anomalies, NCEP/ NCAR Reanalysis data set

2010 2011

2012 Cohen, Barlow, Furtado, Alexeev, Cherry, 2012, ERL

% %

%%%

% %

%%%

% %

%%%

% %

%%%

DJF Trend = 0.07°C/10 yr

MAM Trend = 0.39°C/10 yr**

JJA Trend = 0.38°C/10 yr**

SON Trend = 0.49°C/10 yr**

1990 1995 2000 2005 2010

Time - [year]

[°C

]

0

1

2

0

1

2

0

1

2

0

1

2

[°C

]

[°C]

[°C]

**p < 0.01

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$$

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$ $

0 1-1

[°C per 10 years]

(a) (b)

(c)

(d)

(e)

Northern Hemisphere Land Temperatures 1987-2010

Data: CRU temperature Alexeev et al, 2012, Clim Change; Cohen et al, 2012, ERL

Arctic Trends 1988-2010

2

% %

%%

%

% %

%

#

% %

%%%

6

7

# # # # # #

% %

%%

%

% %

%%

A

B

C

D

E

0

1

-1

[°C

]

0.35

0.45

0.25

[Frac. Area]

12

8

[106 km

2]

7

6

[kg

m-2

]

2

0

-2

[std

]

1990 1995 2000 2005 2010Time - [year]

5

JAS Arctic-MeanTemperature Anomaly

September ArcticSea Ice Coverage

Fall Arctic-Mean Lower Tropospheric Moisture

October EurasianSnow Cover

DJF AO Index

Trend = 0.44°C/10 yr**

Trend = -0.05/10 yr**

Trend = 1.46x106 km2/10 yr**Trend = -0.29x106 km2/10 yr**

Trend = 0.54 kg m-2/10 yr**

Trend = -1.0 std/10 yr** ** p < 0.01

Obs

CMIP5 Ens Mean

 Warming Arctic

 Less sea ice

 More atmospheric moisture

 Increasing snow cover

 Decreasing Arctic Oscillation trend

Alexeev et al, 2005, Clim Dyn; Cohen et al, 2012, ERL

!"#$%&'$()*+,$-./00 12.23

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

!

"

!

Negative Phase of the Arctic Oscillation

[hPa]

!

"

#

$

#

"

!

Tropospheric Winter Trends

Trend in SLP and zonal wind at 10m (ERA-Interim)

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!

"

!U 10m

Temp 100mb

Geop hgt 100mb

Changes in the stratosphere

Alexeev, Ezau, Polyakov, Byam, Sorokina, 2012

Barotropic  vor�city  equa�on    

Resonance:  

ψs ≈ ψ0 /(U −Us)s   ,

Francis, Vavrus, 2013

Z250,  Jan2014  -­‐  climate  

Note: weakening of the gradient (warmer Arctic)

Z500  trend  1988-­‐2013  

Z500  and  T850,  January  

Climate                                          2014  

ECMWF  maps,  Feb  2,  2014  

Changes in January surface air temperature. The Arctic becomes warmer by up to 40°° C but the latitudinal belt south of 60°°N over land becomes colder by up to 8°°C. Newson 1973;

Nature, 241, 39-40

One of the first UKMO GCM sensitivity experiments with polar ice replaced by water at 0°°C

Description of the Numerical Model

-  Upper mixed layer ocean coupled to a full 3D atmospheric GCM

-  Seasonal cycle -  Albedo feedbacks intentionally omitted

(no snow, ice) -  Land points have 10 times lower thermal

inertia than the ocean

Warm  Arc�c  –  Cold  Con�nents  (‘wet’  con�nents,  no  albedo  feebacks)  

‘Reduced’ sea ice – increased heat content before cold season ‘Ghost forcing’ added to Barents and Chukchi seas in summer

Summary/conclusions    The  Arc�c  is  warming,  sea  ice  is  disappearing    North  Atlan�c  warming  and  associated  increase  in  the  

AW  temperature  are  responsible  for  mel�ng  of  a  significant  por�on  of  arc�c  sea  ice  

  Delayed  freeze-­‐up,  more  open  water  and  consequent  heat  input  to  the  atmosphere  lead  to  significant  changes  in  atmospheric  circula�on,  including  switching  the  polarity  of  the  transpolar  dri�  to  posi�ve  phase.  

  Significant  nega�ve  AO/NAO  trend  in  the  recent  years  is  a  manifesta�on  of  the  warming  in  the  Arc�c  Ocean  

  Negative  AO/NAO  trends  are  responsible  for  the  negative  winter  temperature  trends  in  Northern  Eurasia  (also  in  the  lower  48)