sea-ice change around alaska & impacts on human activities...jan 25, 2008 · (rafting vs....

1/25/08 AK Sea Ice Change & Impacts on Human Activities 1

Sea-ice change around Alaska &Impacts on Human Activities

Hajo EickenGeophysical InstituteUniversity of Alaska Fairbanks,[email protected]

• Introduction• The Arctic sea-ice cover:

Observations & predictions• Alaska sea-ice change• Impacts• Conclusions




Observations &predictions

• Alaska sea-ice change• Impacts• Conclusions


Arctic sea-ice summer extent

• 2007 record sea-ice minimum,almost onequarter less in extent than previousrecord minimum in 2005

• Winter ice extent is decreasing but atmuch slower rate: More seasonal ice!

Sep 16, 2007 nsidc.org

Summer minimummedian ice edge (‘79-’00)

Perennialice ‘07


The 2007 record minimum Arctic sea-icesummer extent: Possible explanations

(1) Longer-term retreat pattern roughly inline with what is predicted as result ofglobal warming

(2) Thinner, younger, more mobile icemoves & retreats more quickly in summer

(3) Southerly winds brought warm air andmoved ice towards North Pole in 2007

(4) Warm inflow of water through BeringStrait (?)

(5) Warming of water north of Alaska as aresult of thinned & reduced ice covermelts back ice from below in summer (>7feet of summer bottom melt north ofAlaska!)


The Arctic sea-ice cover: Model projections

Meehl et al., 2007


The Arctic sea-ice cover: Model projections

• Recent summerreductionssomewhatfaster thanmodels predict

• Severalplausibleexplanations,related to howalbedo, icethickness andother factorsare simulated

Stroeve et al., 2007


Minimum ice extent anomalies, onset offreezing/melt, freezing/thawing degree-days

• Reduction in summer ice• Beaufort/Chukchi Seas: Later

freeze-up, reduced freezingdegree-days

NSIDC (2007)

Mahoney et al. (2007)


2007:Record

ice yearin Alaska?

• From June 2007, amount of openwater at record high through Nov

• Barrow air temperature normal inearly summer, above-normal(records broken on 5 days) in latesummer


Summer ice variability:Regional ice regimevs. Arctic ice regime

• Length of Barrow-Prudhoenavigation season, severityof ice in coastal Chukchi-Beaufort Sea in August-September (computed byNational Ice Center)

• Resolution/accuracy ofremote sensing data

• Interannual & local variability• Summer ice incursions


Lead occurrence patterns (1993-2004)

• Winds mostlyfrom ENE(Barrow, 1971-2000) or E(Barter Island,1971-1988)

Grounded ice

“Spring” iceConnected network of open water around floes

Leads at edge of

stable extension

Coastal flooding and melting of landfast ice

Flaw leads and polynyas

Arches and arcing leads


Landfast ice zone

Bottomfast ice

Floatinglandfast ice

Groundedridges (shear/stamukhizone)

Landfast ice extensions

Pack ice


Seasonal cycle of landfast ice extent• Mean controlled

by bathymetry• Maximum

controlled bypack/landfast iceinteraction(stableextension)

• Minimumcontrolled bybreak-out events

• Iñupiaq iceexperts: Break-outs much morefrequent sinceearly 1990s



This study Barry et al. (1979a)

Zone

1

Zone

2

Zone

3

Zone

4

All

zones

Central

Chukchi

Central

Beaufort

MeanDec

01

Oct

25

Nov

04

Nov

9

Nov

7First

Ice*!’ 31.8 9.6 11.4 17.5 16.4

Early

November

Mid

October

First

continuous

fast ice

MeanFeb

23

Jan

22

Jan

28

Jan

27

Feb

01Stable

Ice!’ 41.9 30.1 32.6 34.9 34.1

Feb Jan/Feb

Stable ice

inside of 15

m isobath

MeanJun

04

Jun

11

Jun

04

May

26

Jun

06Break

up!’ 13.9 14.2 13.7 12.6 14.6

Jun 10 Jun 30

First

openings

and

movement

MeanJun

18

Jun

24

Jun

24

Jun

06

Jun

18Ice

Free!’ 12.7 8.4 12.6 10.2 10.4

Jul 05 Aug 01

Nearshore

largely free

of fast ice

*1996-1998 omitted from analysis Mahoney et al. (2007)

1996-2004: E Chuk West Centr East Beauf


Winter sea-ice break-out events

December 13, 2001: Ice breaksout from stretch of coastlineSW of Barrow past NARL (>15 km)

Barrow

Photo: Craig George


Multiple rafting withsediment layers in lowersections

Pack-ice/landfast-ice interaction:Have changes in ice circulationand ice thickness resulted indifferent deformation modes(rafting vs. ridging)?


Ice Push events (ivu)

Fbks Daily News-Miner Jan 25, 2006

Photo: A. Jensen


Solar heating of surface waters in pack ice

Perovich et al.,GRL, 2007

Mea

n an

n. h

eat i

nput

, MJ

m–2

.

Solar heat input at75˚N 165˚W

Solar heating linear trend (% yr–1)• Oceans north ofAlaska have receivedat least twice asmuch heat from sunin recent yearscompared to 1980s


A changing NorthRegime shifts in climate andthe environment that areabout to exceed range ofpast variability and change

Sweeping impacts ofchange on Northernpopulations and cultures

Expansion of globalgeopolitical and economicinterests into the North

Increasing inter-dependence between theArctic region and globalprocesses

BP NorthstarPhoto: BP

Barrow Whaling camp(Photo: Bill Hess) NSIDC

ACIA


Sea-ice systemservices

• Regulating• Climate regulator• Marine & coastal hazard• Stabilizing element in coastal zone• Geologic agent (ice rafting ofsediments, bottom interaction)

• Provisioning• Transportation corridor• Platform (industry & subsistence)• Freshwater source• Source of food

• Cultural• Subsistence activities• Ice as part of cultural & spirituallandscape (incl. tourism)

• Supporting• Ice-based foodwebs• Reservoir and driver of biologicaldiversity (e.g., extremophiles)

(1) Icescape

(2) Platform &Hazard

(3) Habitat


Response to changing conditions:Reexamination of EEZ/territorial claimsin the context of marine transportationand resource extraction (Russia, Den-mark/Greenland, Canada)

ACIA, 2004A

rctic

Res

earch

Com

miss

ion,

200

4


Lease areas in relation to ice conditions

Lease sale data: MMS (2005)


• Ice circulation patterns help bring old (multiyear) ice toBeaufort Sea coast

• If normal ice drift pattern persists, multiyear ice likely to arriveat Barrow by mid/late spring

Dec 1,2007

Jan 1,2008

FYIMYI


Annual sea-ice cycle & operational windowsDecember

March

June

September

Melt

Openwater

Stablelandfastice

Freeze-up &ice advance


Annual sea-ice cycle & operational windowsDecember

March

June

Sep

Melt

Openwater

Stablelandfastice

Freeze-up &ice advance

Spring flooding

Landfast-ice break-outevents

Ice incursions

Early surface meltevents

• Open-wateroperationsregime longer,potential for iceincursions

• Landfast-iceoperationsregime shorter,potential forbreak-outs

• Coastal &offshore iceregime morevariable in time& space

• Highly specific toa given location

Winter-spring icetransition (leaddensities increase)


The value of integrated sea-ice observations• Remote sensing (km-scale): Ice

extent and evolution• Coastal radar (sub-km scale):

Ice dynamics and evolution• EM thickness and DGPS

topography surveys (sub-kmscale)

• Ice mass-balance site (10s m-scale): sealevel , watertemperature, ice & snowthickness & temperature

• Local ice observations (J.Leavitt, A. Brower Sr. andothers): Iñupiaq expertise & iceuse, annual cycle

• Seasonal Ice Zone ObservingNetwork (SIZONet) IPY Project

M. Druckenmiller et al.


IPY-1 at Barrow: US Signal Corps Station• Observation Hut (parts in all likelihood still on site)

• Grounded ice off thebeach in August 1883


0

45

90

1/1 1/31 3/1 3/31 4/30 5/30 6/29 7/29 8/28 9/27 10/27 11/26 12/26

0

12

24Su

n An

gle D

aylight

IPY 1882/83 in context: Melt/Freeze at Barrow (K. Wood, 2004)

2000

1995

1990

1985

1980

1975

1970

188118821883

6/1

9/16

6/13

++++++ ++ + +++ +++++++++ ++

+++++

++

(+)

185218531854

++

(+)

+IPY-1

Maguire (HMS Plover)

IndicatorsFirst BirdsMelt OnsetSnow DisappearsFreeze OnsetLagoons Freeze

+

+

Data sources: US Naval Observatory, Astronomical Applications. NOAA NCDC. R. Stone, NOAA CMDL (Snowmelt). P. Ray, Report of the Point Barrow Exp. R. Maguire, Journal


Advice & guidance from Iñupiat experts

• Murdoch, John. EthnologicalResults of the Point BarrowExpedition. Washington, D.C.:Smithsonian Institution Press,1988. Reprint. Originallypublished: 1892.

Erk-sing-ra: source of localknowledge recorded by Capt.Maguire at Point Barrow inthe 1850s. “[We] had worseseasons before the Shipcame...” Journal of Rochefort Maguire.Photo: US National Archives.


Conclusions• Open water season: longer,

potential for ice incursions (icedetection)

• Landfast ice: extent little changed,less stable (lack of groundedridges and stabilizing factors)

• Coastal zone: Change in icedynamics (rafting, sedimententrainment, break-outs)?

• Multi-year ice reservoir remains inCanadian Arctic with overallthinner ice: More variability

• Role of local expertise inresponding and adapting tochanging conditions

Resources:AOOS:

ak.aoos.orgNWS Anchorage Ice Desk:

pafc.arh.noaa.gov/ice.phpNational Snow & Ice Data Center:

nsidc.orgBarrow/Wales Ice Observatory

www.gi.alaska.edu/BRWICEwww.gi.alaska.edu/WLSICE

University of Alaska IPY Initiativeswww.alaska.edu/ipy“North by 2020 - Forum for localand global perspectives on theNorth”


Case study: Breakout event April 1 & May 28, 2007No. Event Source

1 Few ridges were formed in the landfast ice region off Barrow

due to a lack of a west wind.

Leavitt 2007b

2 There was a lack of multiyear ice incorporated into the

landfast ice. Whaling crews had to haul freshwater to their

camps as opposed to melting multiyear ice.

Brower, H. 2007

3 There was “low-profile” multiyear ice in the landfast ice off

Barrow, as opposed to the “high-profile smooth hills of old

ice” that people are used to seeing.

Brower, A.

2007b

4 There was an “instability” in the landfast ice due to “young

ice forming later in winter.” Also, the pressure ridges were

smaller.

Aiken 2007

5 “Climate change will bring new ice conditions to the

Chukchi [Sea]—young ice will pile up in a new way, even if

thick heavy multiyear ice is not around.”

Brower, H. 2006

www.gi.alaska.edu/BRWICE


• Spatial andtemporalvariability inkey seasonalevents

• Early onset(e.g. PrudhoeBay) vs. lateonset (e.g.,Point Barrow)

• Stable vs.variable iceregimes

• Importance oflocalconditions



Ice morphology

• Potential lackof groundedridges as factorin reduced icestability

• Impact of icemorphology onunder-icecurrents andpotential oildispersal


Multi-year ice incursions

• Reservoir of MY ice north of Canada: Delay of seasonal iceretreat, summer & winter ice hazard, variability in summer iceconditions over shelf

2006

sea-ice change around alaska & impacts on human activities...jan 25, 2008 · (rafting vs....

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