Continued Permafrost Warming in Northern Alaska, 2008 Update Gary - - PowerPoint PPT Presentation

Gary Clow Earth Surface Dynamics

Continued Permafrost Warming in Northern Alaska, 2008 Update

Ocean Observing Systems Atmospheric Observing Systems

GCOS

Terrestrial Observing Systems

Essential Climate Variables: ….

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

….

Permafrost Zones Alaska

Permafrost

Active Layer Continuous Permafrost Discontinuous Permafrost

Permafrost

Active Layer Continuous Permafrost Discontinuous Permafrost

Tair = -8°C Tg = -5°C

mean-annual

Permafrost Zones Alaska

GTN-P: Thermal State of Permafrost

DOI / GTN-P NPR NPR-

• A

A ANWR ANWR

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

measuring circuit located in a thermally controlled Faraday cage Borehole Array DOI/GTN-P Arctic Ocean

Well

Teshekpuk Lake

Borehole Array DOI/GTN-P

Permafrost Temperatures: East Teshekpuk

Temperatures at East Teshepuk about 1.6 years after borehole completion.

Borehole Array DOI/GTN-P

Permafrost Temperatures: East Teshekpuk

Borehole Array DOI/GTN-P

Permafrost Temperatures: East Teshekpuk

Borehole Array DOI/GTN-P

Permafrost Temperatures: East Teshekpuk

Borehole Array DOI/GTN-P

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

Borehole Array DOI/GTN-P

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

Permafrost Temperatures: East Teshekpuk

Borehole Array DOI/GTN-P

Permafrost Temperatures: East Teshekpuk

Borehole Array DOI/GTN-P

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

Permafrost Temperatures: East Teshekpuk

Borehole Array DOI/GTN-P

Permafrost Temperatures: East Teshekpuk

Borehole Array DOI/GTN-P

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.

Permafrost Temperatures: East Teshekpuk

Borehole Array DOI/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

Borehole Array DOI/GTN-P

• 8.1

NPR NPR-

• A

A

• 8.8

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

Brooks Range

• 9.8

Mean-Annual Surface Temperatures (°C), 2007

• 4.6
• 4.5
• 8.3
• 6.4
• 4.5
• 7.7
• 6.3

Borehole Array DOI/GTN-P

• 4.4

NPR NPR-

• A

A

• 6.5
• 7.5
• 6.5

By 2007, surface conditions at some locations on the ACP were approaching those that

• ccur at the Continuous / Discontinuous permafrost boundary (Tg = -5°C).

Brooks Range

• 4.2
• 5.5
• 5.8

[ΔT = 3.5°C]

Mean-Annual Surface Temperatures (°C), 2007

• 4.6
• 4.5
• 8.3
• 6.4
• 4.5
• 7.7
• 6.3

Borehole Array DOI/GTN-P

• 4.4

NPR NPR-

• A

A

• 6.5
• 7.5
• 6.5

By 2007, surface conditions at some locations on the ACP were approaching those that

• ccur at the Continuous / Discontinuous permafrost boundary (Tg = -5°C).

Brooks Range

• 4.2
• 4.3
• 5.5
• 5.8

Tair = -8°C Tg = -5°C

Ice-Wedge Degradation Arctic Coastal Plain

Jorgenson et al., GRL, 2006

• T. Jorgenson
• Have been stable
• n the ACP for

> 3000 years

NPR-A

Ice Wedges

• Take 1000s of years

to form. thermokarst pit

Ice-Wedge Degradation Arctic 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 water

from 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 Degradation Arctic Alaska

changing shoreline environment

August, 2004 thaw slump

Thawing-Degree-Days Maximum Active-Layer Depth Mean-August Temperature Profiles

Fish Creek

2004: a particularly warm summer

Aug 2003

Coastal Erosion Arctic 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

thermokarst gully

Bruce Richmond, USGS

Permafrost Degradation - Arctic Alaska

Bruce Richmond, USGS

Permafrost Degradation - Arctic Alaska

Bruce Richmond, USGS

thaw slump

increased sediment flux from melting permafrost

Permafrost Degradation - Arctic Alaska

40 km

Point Barrow

Drew Point JWD well

Thank you!

• 11
• 10
• 9
• 8
• 7
• 6

1975 1980 1985 1990 1995 2000 2005 2010

Near-Surface Permafrost Temperatures East Teshekpuk, NPR-A

Temperature (°C) Year Near-Surface Temperatures at East Teshekpuk, NPRA

Mean-July Air Temperature (°C)

DOI/GTN-P monitoring network station AK102

Fish Creek - AK102

Future vegetation changes? Fish Creek

DOI / GTN-P Active-Layer Network 1) Automated Permafrost / Climate-Monitoring Stations NPR NPR-

• A

A ANWR ANWR Research + Operational Network

• 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 U31

Marsh Creek, ANWR

Ocean Observing Systems Atmospheric Observing Systems

GCOS

GEOSS

Terrestrial Observing Systems