Transcript Kevin Schaefer guest lecture,

Global Climate Impacts of Thawing
Permafrost
Me
Lin Liu
Alessio
Gusmereli
Tim
Schaefer
Kevin Schaefer
National Snow and Ice Data Center, University of Colorado
Tingjun
Zhang
Permafrost Primer
Permafrost: Ground at or
below 0°C for at least 2
consecutive years
Active Layer: A layer over
permafrost that freezes and
thaws annually
Permafrost Degradation: A
decrease in permafrost
extent; an increase in active
layer thickness.
Skiklomanov [2007]
Permafrost Profile
Vegetation
Organic Layer
Active Layer
Silt
Permafrost
Permafrost Distribution
• ~24% of Northern Hemisphere land
Permafrost Distribution by Country
Permafrost Profile: Mackenzie River
Arctic Ocean
Alberta
Types of Permafrost Models
Observations
Empirical
Component
Complicated
Simple
ALT
Land Ocean
Atmosphere
Land Surface
Parameterizations
Degree Day
Temperature
Temperature,
Moisture, Carbon
Remote Sensing
Diagnostic Models
Prognostic Models
Climate
Feedbacks
Cryoturbation
• Movement of soil or rock due to
repeated freezing and thawing
Vegetation
Active
Layer
Permafrost
Pleistocene Cryoturbation, France
Frost Heave
Frost Boils, Yamal
Stone Circles, Svalbard
Stone Circles, NW Territories
Stripes, Glacier NP
Ice Wedges and Polygons
Polygons, Lena
1st Winter
Active Layer
Frozen
Polygons, Prudhoe Bay [Zhang, 2009]
1st Spring
Thawed
Permafrost
Soil contracts
& cracks
Crack fills with
water & freezes
100th Winter
Frozen
100th Spring
Thawed
Ice
Wedge
Ice Lenses and Layers
Year 10,000
Year 1
Active Layer
Permafrost
Capillary
suction of
water to
permafrost
Ice Lens
Water freezes
& expands
Ice Lenses
Active Layer
Permafrost
Ice Layer
Thermokarst
• Collapse of soil due to melting
of excess ground ice
Projected Temperature Increases
IPCC
Temperature
Projections 4th
Assessment
Report
• 2° to 3° C globally by 2100
• Arctic warming is double the global average
Projected Permafrost Degradation
A1B Scenario Medium Sensitivity
Active Layer Thickness ALT (cm)
Global Terrestrial Network-Permafrost
Circumpolar Active
Layer Monitoring
(CALM) measures
active layer depth
(168 sites)
Thermal State of
Permafrost (TSP)
measures permafrost
temperature (780 sites)
Permafrost is Like Concrete
Wickland
Schaefer
Impacts of Climate Change on
Permafrost
Ecosystems
Infrastructure
Impacts of Degradation
Alaska Road Heaves
Coastal Erosion near Barrow, Alaska
Qinghai-Xizang Highway Bridge
Thermokarst in Yakutsk [Skiklomanov, 2005]
Global Carbon Cycle
Atmosphere
750 Gt + 3 Gt yr-1
120
119
1.9
1.7
90
88
6
Vegetation 600 Gt
Soils 1400 Gt
Permafrost 1466 Gt
Ocean
38,000 Gt
Fossil Fuel
4000 Gt
Impact of Thawing Permafrost on
Global Climate
• ~1700 Gt of carbon
in permafrost as
frozen organic
matter
• Thawing
permafrost will
release CO2 and
CH4
Methane Release from Thawing Permafrost
Methane
emission
Thermokarst
Erosion
Peat
Thaw bulb
Permafrost
Methane
production
Dead
plant &
animal
remains
Burning methane over a
thermokarst lake in
Siberia (K. Walter)
K. Walter [email protected]
Permafrost Carbon Burial
Deposition (loess, peat,
erosion, volcanic)
Active
Layer
Permafrost
Soil
Depth
Permafrost
Horizon
Permafrost Carbon
Mammoth, Siberia
32,000 year old grass, Alaska
30,000 year old roots, Siberia
[Zimov et al., 2006]
15,000 year old moss, North Slope
[Schaefer , 2012]
The Permafrost Carbon Feedback
• Amplifies surface
warming
• Irreversible
• Emissions for centuries
Projected annual permafrost
emissions for A1B scenario
Cumulative NEE (Gt C)
Permafrost Carbon Tipping Point
PCF Tipping
Point 2023±4
Date (year)
Arctic switches from a sink to a source
Permafrost Carbon Flux (Gt C)
Cumulative Permafrost Carbon Flux
104±37 Gt
190±64 Gt
Date (year)
65±23% of15-39%
cumulative
global
sink (~160 Gt C)
of fossil
fuelland
emissions
Estimates of Permafrost Emissions
Schneider et al. (2012)
Zuang et at. (2006)
Dutta et al. (2006)
2100
2200
2300
Koven et al. (2011)
Schuur et al. (2009)
Gruber et al. (2004)
Schaefer et al. (2011)
Burke et al. (2012)
Schuur et al. (2013)
MacDougall et al. (2012)
Raupach and Canadell (2008)
0
100
200
300
400
500
Cumulative Emissions (Gt C)
5% to 39% of anthropogenic emissions
600
Impact on Climate Change Treaty
• 2°C warming target
• Account for permafrost
emissions
• Available Projections don’t
include permafrost emissions
• Temperatures higher with
feedback
• Emissions targets may be too
high
Temperature Projections 4th
Assessment Report
UNEP Recommendations
1) Special IPCC assessment
on permafrost emissions
2) National permafrost
monitoring networks
3) National Adaptation
Plans
The End