Climate Change and the Climate Change and the CryosphereCryosphere

CyrosphereCyrosphere Is the Cryosphere Changing?Is the Cryosphere Changing? How sensitive is the Cryosphere to How sensitive is the Cryosphere to

Climate Change?Climate Change? What will be the impact of future What will be the impact of future

climate change on the Cryosphere?climate change on the Cryosphere? SummarySummary

CryosphereCryosphere Represents all global snow and iceRepresents all global snow and ice Covers 10% of the worldCovers 10% of the world Contains about 2.4% of all water…Contains about 2.4% of all water…

makes up nearly 80% of all fresh makes up nearly 80% of all fresh waterwater

Cyrosphere-Contin.Cyrosphere-Contin. Includes:Includes:

• Seasonal snowSeasonal snow• Mtn. GlaciersMtn. Glaciers• Ice capsIce caps• PermafrostPermafrost• River iceRiver ice• Lake iceLake ice

Cryosphere ContinuedCryosphere Continued Each winter, the seasonal snow cover Each winter, the seasonal snow cover

grows to cover…..grows to cover…..1/4 of N. 1/4 of N. HemisphereHemisphere

Sea Ice dominates Arctic and Sea Ice dominates Arctic and Southern OceansSouthern Oceans

P’frostP’frost and and seasonally frozen soilsseasonally frozen soils underlie as much as 25% of the underlie as much as 25% of the global land surfaceglobal land surface

Cryosphere-ContinuedCryosphere-Continued Projected changes in climate will Projected changes in climate will

substantially reduce the substantially reduce the arealareal extent extent and and volumevolume of the cryosphere. of the cryosphere.

ImpactsImpacts….reduction will have ….reduction will have significant impacts on related significant impacts on related ecosystemsecosystems (both natural and (both natural and managed) and on social and managed) and on social and economic activities and on sea level economic activities and on sea level changeschanges

Cryosphere-Contin.Cryosphere-Contin. Landscapes may Landscapes may

change in change in glacerized and glacerized and permafrost areaspermafrost areas

Is the Cryosphere Changing?Is the Cryosphere Changing? Snow coverSnow cover

• Remote sensing since 1968 indicates Remote sensing since 1968 indicates considerable variability from year to yearconsiderable variability from year to year

• i.e. annual max. snow area of Eurasia i.e. annual max. snow area of Eurasia changes by changes by +/- 350, 000 Km+/- 350, 000 Km22, therefore long-, therefore long-term patterns of continuous snowcover is term patterns of continuous snowcover is difficult to detect.difficult to detect.

• It has been found (Robinson and Deuly, It has been found (Robinson and Deuly, 1991) that the extent of northern hemisphere 1991) that the extent of northern hemisphere snow to be at a record low levels after 1987.snow to be at a record low levels after 1987.

• **largest negative snow anomalies of recent **largest negative snow anomalies of recent years are occurring in springyears are occurring in spring

Changing-ContinuedChanging-Continued ……to lower depths to lower depths

in early winter in early winter (Dec. Jan)…but (Dec. Jan)…but delayed ablation in delayed ablation in springspring

*snow avalanches*snow avalanches …no clear …no clear temporal trends temporal trends nor a regular nor a regular periodicityperiodicity

ACIA, 2005: www.acia.uaf.edu

Ice Caps and GlaciersIce Caps and Glaciers Mass loss and retreat of mountain Mass loss and retreat of mountain

glaciers during the glaciers during the 2020thth century is century is strikingstriking all over the world. all over the world.

EuropeEurope• Since the middle of the past century…Since the middle of the past century…

end of the “Little Ice Age”, the glaciers end of the “Little Ice Age”, the glaciers have lost about have lost about 30 to 40 % in surface 30 to 40 % in surface areaarea and around and around 50% in ice volume50% in ice volume

ContinuedContinued Glacier mass loss is consistent with Glacier mass loss is consistent with

anthropogenic greenhouse forcing anthropogenic greenhouse forcing (2-3 Wm(2-3 Wm-2-2))

Glacier wastage increase in EuropeGlacier wastage increase in Europe• i.e. N. Sweden-only i.e. N. Sweden-only +8 mass+8 mass balance balance

years between 1946 and 1980years between 1946 and 1980

ContinuedContinued Can. High Arctic…30 years of data, Can. High Arctic…30 years of data,

show show slightly “-ve” balancesslightly “-ve” balances… but no … but no sign. trendssign. trends• But did see But did see surface lowering in the surface lowering in the

ablation zoneablation zone• NOWNOW, starting to see significant –ve , starting to see significant –ve

balances…the summer ablation period is balances…the summer ablation period is MOST importantMOST important

ACIA, 2005: www.acia.uaf.edu

PermafrostPermafrost

Deep boreholes in Alaska and Deep boreholes in Alaska and Canada…show a distinct but Canada…show a distinct but spatially heterogeneous spatially heterogeneous warming trend during the warming trend during the past century-past century-*poor *poor distribution of bore holesdistribution of bore holes

River and Lake IceRiver and Lake Ice

Soviet Union-regional trend is Soviet Union-regional trend is for later river-freeze-up for later river-freeze-up date….about 2 to 3 weeksdate….about 2 to 3 weeks

Further east-a weaker trend Further east-a weaker trend occursoccurs

ContinuedContinued Magnuson et al. 2000 note that with Magnuson et al. 2000 note that with

increasing temperature, there have been increasing temperature, there have been noticeable changes in the dates of freeze noticeable changes in the dates of freeze up and breakup in many lakes and rivers up and breakup in many lakes and rivers of the Arctic.of the Arctic.

The average change over the The average change over the 150-year 150-year periodperiod was nearly was nearly nine days later for nine days later for freeze upfreeze up dates and almost dates and almost 10 days earlier 10 days earlier for ice breakupfor ice breakup dates of rivers and lakes in dates of rivers and lakes in the Northern Hemispherethe Northern Hemisphere

Sea IceSea Ice ArcticArctic-remote -remote

sensing-since sensing-since 1973, no 1973, no convincing convincing evidenceevidence

Longer datasets Longer datasets are neededare needed to test to test whether a genuine whether a genuine long-term trend is long-term trend is occurringoccurring

How sensitive is the Cryosphere to How sensitive is the Cryosphere to Climate Change?Climate Change?

SnowcoverSnowcover•Snow cover in temperate regions is generally thin (a few metres or less) and often close to its melting point

•Therefore, continentalcontinental andand alpinealpine snow covers are very snow covers are very sensitive to climate changessensitive to climate changes

Snowcover-ContinuedSnowcover-Continued Climate change alters both the quantity,

duration and structure of the snow! Snow exerts both a direct, positive

feedback on climate and an indirect, negative feedback. The stronger positive feedback means that a decrease in snowcover makes the earth less reflective…causing it to warm…as it absorbs more solar radiation

Snowcover-ContinuedSnowcover-Continued

But warmer surface But warmer surface L L, which , which serves to cool “somewhat” serves to cool “somewhat” warming. warming.

Also, clouds may Also, clouds may over these over these zones….zones…. heating. heating.

Ice Caps and GlaciersIce Caps and Glaciers For a For a great #great # of glaciers, the of glaciers, the sensitivitysensitivity of of

terminal response depends on whether a terminal response depends on whether a lake is present or not.lake is present or not.

Lakes give a high degree of Lakes give a high degree of instabilityinstability……minor variations in distal thickness of ice minor variations in distal thickness of ice tongues allow floatation and rapid calving.tongues allow floatation and rapid calving.

Retreat is slowerRetreat is slower if no lakes form if no lakes form Glaciers….basal melting are observed to Glaciers….basal melting are observed to

re-advance when climate is favorablere-advance when climate is favorable

ContinuedContinued ……therefore, many glacier tongues therefore, many glacier tongues

show a high degree of sensitivity to show a high degree of sensitivity to quite small changes in climate….quite small changes in climate….

PermafrostPermafrost Ice melt at the permafrost tableIce melt at the permafrost table Increase in the active layer thicknessIncrease in the active layer thickness

Ground SurfaceGround Surface

Frost TableFrost Table

Permafrost TablePermafrost Table

Conc. of IceConc. of Ice

Active LayerActive Layer

ContinuedContinued Direct ResponseDirect Response

• Takes yearsTakes years -disturbance of -disturbance of temperature profiles within the temperature profiles within the permafrost may be delayed for permafrost may be delayed for decades to centuriesdecades to centuries

• DisplacementDisplacement of the permafrost of the permafrost base…final response requires base…final response requires centuries to millenniacenturies to millennia

O Deg. CO Deg. C

ColderColder WarmerWarmer

Permafrost BasePermafrost Base

UnfrozenUnfrozen

FrozenFrozen

High Energy Demand to Melt IceHigh Energy Demand to Melt Ice

ContinuedContinued Simulations performed by Simulations performed by

Riseborough and Smith (1993) Riseborough and Smith (1993) suggest that the rate of thaw and suggest that the rate of thaw and disappearance of thin (4.5 m) disappearance of thin (4.5 m) permafrost in Central Canadapermafrost in Central Canada

……Inter-annual VariabilityInter-annual Variability

Contemporary and Future Areas of Contemporary and Future Areas of Permafrost in the N. Hemisphere Permafrost in the N. Hemisphere

(1000 km(1000 km22)) Zone Now Year 2050 Contin.Contin. 1173811738 85178517

Discontin.Discontin. 55885588 49614961

SporadicSporadic 81308130 79147914

River and Lake IceRiver and Lake Ice A 3 Deg. C rise in April Air TemperatureA 3 Deg. C rise in April Air Temperature

between 1870 and 1950 is associated with between 1870 and 1950 is associated with an approx. an approx. 15 day advance15 day advance in break-up in in break-up in ScandinaviaScandinavia

Break-up of the St. John River in Canada is Break-up of the St. John River in Canada is similarsimilar• Overall…the sensitivity of both freeze-Overall…the sensitivity of both freeze-

up and break-up is about up and break-up is about 5 days per 5 days per Deg. C.Deg. C. The sensitivity for the length of The sensitivity for the length of the ice season is about the ice season is about 10 days per Deg. 10 days per Deg. C.C.

What will be the impact of future What will be the impact of future climate change on the Cryosphere?climate change on the Cryosphere?

SnowSnow• Lowland continental snowcover will be Lowland continental snowcover will be

diminished in extent, duration and depth diminished in extent, duration and depth given by climate change scenariosgiven by climate change scenarios

• Winter snowlines could move further Winter snowlines could move further north by north by 5-10 Deg./latitude5-10 Deg./latitude

• The snow season could be shortened by The snow season could be shortened by more than a month, depending on snow more than a month, depending on snow depthdepth

ContinuedContinued In polar regions, snowmelt is delayed In polar regions, snowmelt is delayed

until near the summer solstice, when until near the summer solstice, when solar radiation input is largesolar radiation input is large• Snowfall laterSnowfall later• Snowmelt earlierSnowmelt earlier• Snowfree season extendedSnowfree season extended• In High ArcticIn High Arctic …advance in melt time… …advance in melt time…

less pronounced…the snow is very coldless pronounced…the snow is very cold

ContinuedContinued AntarcticaAntarctica-summer -summer

temperatures are temperatures are so low that the so low that the present regime of present regime of little or no little or no snowmelt will snowmelt will persistpersist

Ice Caps and GlaciersIce Caps and Glaciers Empirical and energy balance Empirical and energy balance

considerations indicate that considerations indicate that 1/3 to 1/3 to 1/21/2 of Mt. Glaciers mass could of Mt. Glaciers mass could disappear over the next 100 yearsdisappear over the next 100 years

shift of the Equilibrium Line by shift of the Equilibrium Line by 200 200 to 300to 300 m-yearly thickness losses of m-yearly thickness losses of 1 1 to 2 mto 2 m for temperate glaciers for temperate glaciers

Arctic GlaciersArctic Glaciers

Arctic GlaciersArctic Glaciers Increase ablation at low Increase ablation at low

altitudesaltitudes•Increase accumulation at Increase accumulation at higher levelshigher levels

•Ice caps may grow?Ice caps may grow?

Ice SheetsIce Sheets Ice SheetsIce Sheets

• Significant surface melt of the Significant surface melt of the Antarctic and Greenland Ice SheetsAntarctic and Greenland Ice Sheets

• Is important only over a small Is important only over a small coastal area and only at the height coastal area and only at the height of summerof summer

• In Greenland, more ice claving and In Greenland, more ice claving and melt at the margins is expected.melt at the margins is expected.

PermafrostPermafrost All All interactionsinteractions are quite are quite complexcomplex There will be substantial There will be substantial poleward poleward

migrationmigration of the discontinuous and of the discontinuous and continuous permafrost zonescontinuous permafrost zones

More studies… More studies… role of latent heatrole of latent heat associated with ablation of ground iceassociated with ablation of ground ice• DiscontinuousDiscontinuous….disappear….disappear• ContinuousContinuous….thickening of the active ….thickening of the active

layerlayer

ContinuedContinued Significant Significant increase in the active layer increase in the active layer

depthdepth, or loss of permafrost is expected to , or loss of permafrost is expected to cause drying of the upper soil layers in cause drying of the upper soil layers in most regions and enhanced decomposition most regions and enhanced decomposition of soil organic matterof soil organic matter

LossLoss of a sizeable portion of more than of a sizeable portion of more than 506 t of 506 t of carbon in Arctic soilscarbon in Arctic soils and 450 GT and 450 GT of carbon presented in soils of all northern of carbon presented in soils of all northern ecosystems will cause an appreciable ecosystems will cause an appreciable “+ve“+ve” feedback on atmospheric rise of ” feedback on atmospheric rise of C0C022

Wetlands…Wetlands…methanemethane??

River and Lake IceRiver and Lake Ice Duration of river ice cover will be Duration of river ice cover will be

reducedreduced• Delay in freeze-upDelay in freeze-up• Advancement of break-upAdvancement of break-up• The frequency and magnitude of major The frequency and magnitude of major

frazil-ice growth periods could be frazil-ice growth periods could be reducedreduced

• Alter ice typesAlter ice types….hydro-technical ….hydro-technical problemsproblems

ContinuedContinued Many rivers within the more temperate Many rivers within the more temperate

regions will regions will become ice-freebecome ice-free or develop only or develop only intermittentintermittent or or partial ice coveragepartial ice coverage. Ice . Ice growth thickness will be reduced. In colder growth thickness will be reduced. In colder regions, the present ice season could be regions, the present ice season could be shortened by up to a month by 2050.shortened by up to a month by 2050.

Warmer winters will cause mid-winter break-Warmer winters will cause mid-winter break-ups as rapid snowmelt is ups as rapid snowmelt is initiated…rain-on-initiated…rain-on-snow eventssnow events …become more common …become more common

LakesLakes Duration of a lake ice cover will be Duration of a lake ice cover will be

shortenedshortened, longer, open water will , longer, open water will increase evaporation lossincrease evaporation loss

Patchy wetlandsPatchy wetlands …enhanced …enhanced evaporation and ground thaw will evaporation and ground thaw will cause some to disappearcause some to disappear

0

20

40

60

% S

NO

W C

OV

ER

JULIAN DAY170 180 190 200 210 220 230

1996199719982000

200120022003

• Seasonal change in the percentage cover of a late-lying snowbank near Resolute that feeds a wetland below it. Note the year to year variations in the seasonal shrinkage of the snowbank.

1997

2001

Sea IceSea Ice Both +ve and –ve feedbacksBoth +ve and –ve feedbacks 8 Deg. C rise8 Deg. C rise……

• NWNW passage and passage and Northern Sea RouteNorthern Sea Route … …will lead to a will lead to a decline in winter fast icedecline in winter fast ice thickness from 1.8 to 2.5 m at present thickness from 1.8 to 2.5 m at present to 1.4 to 1.8 m, depending on snow to 1.4 to 1.8 m, depending on snow thicknessthickness

But But more open watermore open water, more ppt may , more ppt may increase snow and may increase ice increase snow and may increase ice thicknessthickness

ContinuedContinued Still very unclear-Still very unclear-

need coupled need coupled ocean-ice-ocean-ice-atmosphere atmosphere models…results models…results not yet availablenot yet available

SummarySummary CyrosphereCyrosphere Is the Cryosphere Changing?Is the Cryosphere Changing? How sensitive is the Cryosphere to How sensitive is the Cryosphere to

Climate Change?Climate Change? What will be the impact of future What will be the impact of future

climate change on the Cryosphere?climate change on the Cryosphere?

IPPC-2007 Report