continued permafrost warming in northern alaska, … · continued permafrost warming. in northern...

Gary ClowEarth Surface Dynamics

Continued Permafrost Warmingin Northern Alaska, 2008

Update

OceanObservingSystems Atmospheric

ObservingSystems

GCOSTerrestrialObservingSystems

Essential Climate Variables:

….• permafrost - active layer thickness (GTN-P)• permafrost - thermal state (GTN-P)

….

Permafrost ZonesAlaska

Permafrost

Active Layer

Continuous Permafrost Discontinuous Permafrost

Permafrost

Active Layer

Continuous Permafrost Discontinuous Permafrost

Tair = -8°CTg = -5°C

mean-annual

Permafrost ZonesAlaska

GTN-P: Thermal State of Permafrost

DOI / GTN-P

NPRNPR--AA

ANWRANWR

Temperatures are periodically remeasured in the DOI/GTN-P boreholes using the USGS’sPolar Temperature Logging System. System sensitivity is ~ 0.2 mK, uncertainty = 3.3 mK.

Atigaru Point

measuring circuitlocated in a

thermally controlledFaraday cage

Borehole ArrayDOI/GTN-P

Arctic Ocean

Well

TeshekpukLake

Borehole ArrayDOI/GTN-P Permafrost Temperatures: East Teshekpuk

Temperatures at East Teshepuk about 1.6 years after borehole completion.


Northern Alaska experienced a mild cooling during 1983-84. Just a hint of that cooling is visible in the 1984 East Teshekpuk log (it’s much more apparent at other sites).

Permafrost Temperatures: East Teshekpuk


Temperature logs acquired during 1989 began to show a recovery from the mid-1980’s cooling.



The climate record during the 1990’s was clearly different from that during the 80’s and late 70’s.



Measured temperature profiles with preliminary extrapolated surface temperatures. Surface temperatures were ~ 3.6°C warmer during 2007 than during the late-70’s, early-80’s.


Borehole ArrayDOI/GTN-P Permafrost Temperatures: South Meade

Surface temperatures were ~ 4.6°C warmer at South Meade during 2007 than during the late-70’s, early-80’s.

South Meade

Mean-Annual Surface Temperatures (°C), 1989

-9.3 -9.6-10.6

-10.2

-9.8

-7.0

-10.2

-9.7


-8.1

NPRNPR--AA

-8.8

Arctic Coastal Plain (ACP) was well within the Continuous Permafrost Zone in 1989 (Tg < -5°C).

Brooks Range

-9.8


-4.6-4.5

-8.3

-6.4

-4.5

-7.7

-6.3


-4.4

NPRNPR--AA

-6.5-7.5

-6.5

By 2007, surface conditions at some locations on the ACP were approaching those thatoccur at the Continuous / Discontinuous permafrost boundary (Tg = -5°C).

Brooks Range

-4.2

-5.5

-5.8

[ΔT = 3.5°C]


-4.6-4.5

-8.3

-6.4

-4.5

-7.7

-6.3


-4.4

NPRNPR--AA

-6.5-7.5

-6.5

By 2007, surface conditions at some locations on the ACP were approaching those thatoccur at the Continuous / Discontinuous permafrost boundary (Tg = -5°C).

Brooks Range

-4.2-4.3

-5.5

-5.8

Tair = -8°CTg = -5°C

Ice-Wedge DegradationArctic Coastal Plain

Jorgenson et al., GRL, 2006

T. Jorgenson

• Have been stableon the ACP for> 3000 years

NPR-A

Ice Wedges

• Take 1000s of yearsto form.

thermokarst pit

Ice-Wedge DegradationArctic Coastal Plain Jorgenson et al., GRL, 2006

T. Jorgenson

• Area/density of thermokarst pits abruptly increased an order of magnitude after 1982; an event of similar magnitude probably hasn’t occurred in the past 3,000 years.

area of thermokarst pits = 0.5% 0.6% 4.4%

density of pits = 88/km2 128/km2 1336/km2

• Degradation of ice wedges has caused a substantial redistribution of surface waterfrom the adjacent tundra into the degraded trough network.

• If the trend continues, 10-30% of the terrestrial landscape may be directly effected.

• Enhanced degradation was due to warmer summer temperatures during 1989-1998.

Permafrost DegradationArctic Alaska

changing shoreline environment

August, 2004thaw slump

Thawing-Degree-Days

Maximum Active-Layer Depth

Mean-August Temperature ProfilesFish Creek

2004: a particularly warm summer

Aug 2003

Coastal ErosionArctic Alaska

August, 2003

Susan Flora, BLM

Sept 2004 = 100 m Erosion

July 2003 = 35 m Erosion

July 2001

1998

July 2003

Sept 2004

Wind Speed, AK102

S. Flora, BLM

S. Flora, BLM

J.W. Dalton Wellsite

Coastal Erosion - Drew Point, Arctic Coast

Ben Jones, USGS

Permafrost Degradation - Arctic Alaska

ice wedges, advanced degradation

Bruce Richmond, USGS

thermokarstgully




thaw slump

increased sediment fluxfrom melting permafrost


40 km

Point Barrow

Drew Point

JWDwell

Thank you!

-11

-10

-9

-8

-7

-6

1975 1980 1985 1990 1995 2000 2005 2010

Near-Surface Permafrost TemperaturesEast Teshekpuk, NPR-A

Tem

pera

ture

(°C

)

Year

Near-Surface Temperatures atEast Teshekpuk, NPRA

Mean-July Air Temperature (°C)

DOI/GTN-P monitoring networkstation AK102

Fish Creek - AK102

Future vegetation changes?

Fish Creek

DOI / GTN-P Active-Layer Network

1) Automated Permafrost / Climate-Monitoring Stations

NPRNPR--AA

ANWRANWR

Research + OperationalNetwork

• ground temperature (10 depths)• soil moisture• air temperature• pressure*• wind speed & direction• rain*• snow depth• up- and downwelling shortwave radiation• albedo

GCOS/GTOS/GTN-P Station U31Marsh Creek, ANWR

OceanObservingSystems Atmospheric

ObservingSystems

GCOS

GEOSS

TerrestrialObservingSystems

continued permafrost warming in northern alaska, … · continued permafrost warming. in northern...

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