The Arctic on the Fast Track of Change

Julienne Stroeve

Climate change in the Arctic: A Bellwether for the Planet

Bellwether (1) - One that serves as a leader or as a leading indicator of future trends

Bellwether (2) - Sheep that leads the herd often wearing a bell

Inuksuk - a stone landmark used as a milestone or directional marker

Air Temperature: A1B Scenario by 2100

Global mean warming of ~2.8oC (or ~5F);Much of land area warms by ~3.5oC (or ~6.3F)

Arctic warms by ~7oC (or ~12.6F)

IPCC-AR4 ensemble mean, A1B Scenario, courtesy M. Holland

Amplified Arctic warming

Signs of warmer Arctic: Increasing Greenland melt

2007 Melting Day Anomalies

Melting Index Time Series

Courtesy M. Tedesco

Speed-up of many of Greenland’s outlet glaciers

• Current mass loss for Greenland is equally split between surface melt/runoff and ice discharge across calving fronts.

• Future prediction of Greenland’s contribution to sea level rise is difficult because it is unclear how these outlet glaciers will respond.

• Melting of Greenland would produce 7.2 m sea level rise (or about 24 ft).

Jacobshavn Glacier retreat: The rapidly retreating Jakobshavn Glacier in

western Greenland drains the central

ice sheet

Image courtesy NASA Earth Observatory, Cindy Starr, based on data from Ole Bennike and Anker Weidick (Geological Survey of Denmark and Greenland) and Landsat data.

Glacier Fluctuations: clear indicators of a warming climate

1958 2003

McCall Glacier

1941 2004

Muir Glacier

Glacier image archive available from NSIDC

Average mass balance of a few Arctic glaciers

-0.5

-0.4

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1960 1970 1980 1990 2000 2010

Arctic period 1Arctic period 2

y = -6.7749 + 0.0033902x R= 0.23585

y = 43.522 - 0.02189x R= 0.81179

Year

Mass balance of Arctic glaciers show shift towards acceleration mass loss from 1988 (mass balance is in m of water equivalent)

Recent decades show less variability and consistent negative trends.

Permafrost degradation

Permafrost regions occupy 24% of the Northern Hemisphere and occur as far north as 84oN and as far south as 26oN in the Himalayas.

Greenland

SiberiaAlaska

Increases in permafrost temperature

• Alaska: 4 to 6oC increase in 20th Century, 2 to 3oC in last 30 years

• Siberia: >3oC increase from mid-1950s to 1990

• Canadian Arctic: 1 to 3oC increase in past several decades

• Tibetan Plateau: up to 1.0oC increase since 1970s

Russian Permafrost Temperature

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1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Year

Te

mp

era

ture

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par

ture

(°C

)

0.2 m; Trend = 0.78°C/decade

0.4 m; Trend = 0.79°C/decade

0.8 m; Trend = 0.65°C/decade

1.6 m; Trend = 0.55°C/decade

3.2 m; Trend = 0.66°C/decade

Alaskan permafrost temperatures, 20 m deep Soil temperatures in the active layer and upper permafrost

Courtesy T. Zhang

Infrastructure impactsChersky, Russia

Qinghai-Xizang Highway bridge collapse

Alaska

Alaska

Courtesy T. Zhang

Methane releasing from lakes

Burning methane over a thermokarst lake in Siberia (K. Walter)

Methane bubbles trapped in lake ice

Lake bubbling with methane in the Arctic

Courtesy K. Walter

“Greening” of the Arctic

Trends in vegetation synthetic activity from 1982–2005 (GIMMS-G AVHRR Vegetation indices)

Significant positive trends

Significant negative trends

Courtesy S. Goetz, Woods Hole

Greenland

Poster child of climate change: Arctic sea ice• Frozen surface of the ocean –

originates within ocean Does not include land ice

(glaciers, ice sheets) Does not include other floating

ice (ice shelves, icebergs) If sea ice melts, sea level will not

riseNOAA

Pancake Ice

Ridged IceIce Floes

Multiyear Ice

Just to be clear, sea ice is not icebergs!

Courtesy Sebastian Copeland

Annual sea ice variability

Maximum extent occurs in February/March (14-16 million km2

or 5-6 million square miles) , minimum extent occurs in September (7-8 million km2 or about 3 million square miles)

February

September

Gre

en

lan

d

Gre

en

lan

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Siberia Siberia

Alaska

Alaska

Recent changes in Arctic sea ice• Previous studies have indicated a decline in annual Arctic sea ice cover since

the late 1970s at a rate of -3%/decade or a loss in ice area of nearly 300,000 sq-km [e.g. Parkinson et al., 1999; Cavalieri et al., 1997; Bjorgo et al., 1997].

Current trend since 1979 is now at -4.3 % per decade

Losing the summer sea ice cover

Time-series of September ice concentration during the modern satellite data record (1979 to 2010)

Stroeve et al. 2008

September 2007: A new record minimum

Alaska

Sib

eria

Greenland

What caused the ice cover to drop in 2007?• Unusual atmospheric circulation pattern that promoted

warm temperatures and strong winds.

A very Warm ArcticStrong ice drift away from Siberian coast across the Arctic

Sea Ice MotionJune and July Temperature Anomaly

What caused the ice cover to drop in 2007?

• Big culprit was a thin ice pack.

Image courtesy of R. Kwok

Some recovery since 2007, but still in decline

1979-2000

2009

20072008

Variability points to importance of summer circulation influence

Large changes in the distribution of ice age

• Unfortunately we don’t have long-term records of Arctic-wide ice thickness measurements.

• Tracking the age of the sea ice is one means to look a past thickness distribution, since older ice tends to be thicker.

Spring 1986 Spring 1990 Spring 2007

Maslanik et al., 2007

Very little old ice left

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March Ice Age Distribution (Week 11)

5+ winter extent4 winter extent3 winter extent2 winter extent1 winter extent

Year

Ex

ten

t (m

illio

n s

q-k

m)

Only 320,000 km2 of ice 5+ years

Less than 60,000 km2 of 5+ ice left in September 2010

• Less than 15% of the remaining ice is more than 2 years old, compared to 50-60% during the 1980s

1985

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8End of Summer Ice Age Distribution

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Ext

ent

(mil

lio

n s

q-k

m)

Arctic sea routes opening up

NW Passage opening up (2007-2010)

Conditions in 2007

NSR also open (2008-2010)

Conditions in 2008

Peering into the Future

Continued sea ice loss inevitable• Seasonally ice free Arctic sooner than we expect?

Updated from Stroeve et al., 2007

1900 1920 1940 1960 1980 2000 2020 2040 2060 2080 21000

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10September Sea Ice Extent

Ice

Ext

ent

(mill

ion

sq

-km

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Models suggest ice-free conditions may occur quickly

• Climate models suggest once the sea ice cover is thinned sufficiently, a strong “kick” from natural variability can initiate a rapid slide towards ice-free conditions in summer [e.g. Holland et al., 2006].

CCSM3 model simulationObservations

Model drop1.8 million sq km, 2024–2025

Observed drop1.6 million sq km, 2006–2007

The set up looks right

• Mean thickness (70-90N) in CCSM3 before abrupt change: 1.71 m

• Mean thickness (70-90N) from ICESat in Spring 2007: 1.75 m (data from D. Yi and J. Zwally)

Increased Access to the Arctic

Zinc & Coal

Today’s Arctic marine use

Snapshot of Summer 2004

Traffic ~ 5475 Ships

Hard Minerals

Nickel & Copper

High grade Iron Ore

Maritime Tourism

Major Fisheries

Oil and GasSummer Sea LiftExploration/Science

In 2004 there were ~5500 ships

Distribution of known resourcesUSGS estimated in 2008 that 90 billion barrels of oil, 1,700 trillion cubic feet of natural gas and 44 billion barrels of natural gas liquids may be found in the Arctic, of which ~84% occurs offshore.

Oil Gas

Impact on polar bears and other Arctic species

Polar bears under pressure

• For every week a bear has not been hunting, it is 22 pounds lighter. The bear’s reproductive

system is strongly linked to their fat stores.

• The offshore ice-based ecosystem is sustained by upwelling nutrients that feed the plankton, shrimp, and other small organisms, which feed the fish. These in turn feed the seals, which feed the bears.

Seals also feeling impacts

• Lack of sea ice the last 2 years in the Gulf of St. Lawrence led to loss of thousands of baby harp seals.

• Canada Fisheries reported that on the first day of spring 2010, there were only 600 seals in the gulf, when normally there are 30,000.

Seal image courtesy Sebastian Copeland

Community impactsMany Arctic indigenous communities rely on sea ice for travel and hunting, their main livelihood and basis for their cultural identity

Photo by Craig George

Impacts of changing sea ice on food resources• Reductions in sea ice

are shrinking the marine habitat for ice-dependent seals, walrus, polar bears and some seabirds.

• Sea-ice is thinner and now drifts far away during the summer, taking with it the seals, walrus and polar bears upon which the village’s Inuit residents rely for food.

Courtesy S. Gearheardt

Safety issues• Changes in sea ice -

local and regional thinning, unusual cracks, changes in the timing of break up and freeze up are already having a serious impact on travel safety. Before venturing

onto ice in fall or spring, hunters are encouraged to test its stability with a harpoon.

Courtesy S. Gearheardt

Community locations threatened• Native communities are facing erosion problems and relocation

of communities (at huge costs) as a result. Lack of sea ice cover exposes shoreline to waves and storms.

Photo Craig George

Sea ice in spring

Climate impacts for the rest of us

Ice albedo feedback: ice edge retreat

Ice-Albedo Feedback-Amplifier of Climate Change

Ice albedo feedback:

Largest albedo to smallest

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1.0

Alb

edo

Snow

Ocean

85%

7%

Autumn (SON) air temperature anomalies: 2004-2008 minus 1979-2008

Updated from Serreze et al., 2008

Arctic Amplification has already emerged

SiberiaG

reen

land

Alaska

Impact of sea ice loss on land temperatures

Permafrost contains about 1672 Gt of carbon. For comparison, carbon content of Earth’s atmosphere: ~730 Gt today.

Courtesy D. Lawrence

Results: Strength of the PCF

PCF Start 2023±4

Date (year)

Cum

ulat

ive

NE

E (

Gt C

)

Paper in Tellus-B

Impacts on precipitation/snow cover• A warmer atmosphere changes atmospheric

circulation and is able to hold more water vapor and thus could lead to more precipitation, especially in autumn and winter.

Courtesy of Rutgers University Climate Lab

Final Statements

• Continued ice loss will likely have significant impacts beyond the Arctic.

• Land and ocean ice loss in the Arctic is consistent with model simulations made with observed records of GHGs.

• Many components of the Arctic environment are undergoing large changes.

• Sea ice loss is already affecting the environmental, biological and societal systems in the Arctic.

• Sea ice loss is outpacing climate model projections, ice free summers by 2050?

Climate Change and Colorado’s Future

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