Professor Mary Edwards, from the Geography Department at Southampton University, talks about The Big Thaw: A warming, changing Arctic. She considers the fragility of Arctic systems, drawing upon examples from Alaska, where she lived for several years, and Siberia, the largest northern land area affected by warming.

1. The Big Thaw: a warming,
changing Arctic
Mary Edwards
Southampton
Isle of Wight Café Scientifique 2016

2. Fieldwork funded by
NATIONAL SCIENCE
FOUNDATION
EU-ECOCHANGE
NERC
Acknowledgements
PAT MCDOWELL
GUIDO GROSSE
BEN JONES
KATEY WALTER
BRUCE FORBES
The late DAVID HOPKINS
TEREZA ŠMEJKALOVÁ
JADU DASH
JOSH ROSE

4. Arctic ambition:
The race to sail
Northwest
Passage heats
up.
Ollie Williams, for CNN
September 8, 2014
University of Durham

5. 2007 Warming 'opens Northwest Passage'
The most direct shipping route from Europe to Asia is fully clear of
ice for the first time since records began.
NSIDC

6. Franklin expedition
Northwest Passage 1845-1848
Ships iced in for a whole
summer. All hands lost from
starvation
Devon Island
The difference in mean temperature?
< 1°C globally, ~2°C in the Arctic
CRU

7. There is not only a trend in ice extent, but also a
trend in ice thickness—sea ice is getting thinner
(U.S. Navy)

8. A trend of decreasing sea-
ice extent at the end of each
NH summer-each line
represents a different year
NSIDC
2012
Thick
black
line in
upper
bundle
is the
1981-
2010
mean
Upper
bundle
1987-
2003
Lower
bundle
2007-
2015
2013

9. Esa's Cryosat sees Arctic sea-ice
volume bounce back
2016 – area has
reduced again –
2013 still 6th
smallest in satellite
record

10. 10
Is any of this this Arctic change?
“Climate is what you expect. Weather is what you get”
Mark Twain
Climate is average weather—statistics
Climate change is identified via multiple observations – over
decades
“One swallow does not a summer make, nor one fine day….”
Aristotle
Weather is highly variable, one observation does not signal
change; but also one oddity in a trend is not a reversal
Applies to effects of climate change also…e.g., sea ice

11. ARCTIC (POLAR) AMPLIFICATION
Cohen et al.
2014. Nat Geo
Winter decadal trends

12. IPCC (2014) projections for end-C21st (low and high
emissions pathways)
Arctic warms about x2 compared with low latitudes

13. Causes of Polar Amplification
Local/regional radiative changes due to greenhouse forcing (slower
rate of heat loss)
Seasonal reductions in cover and duration of snow and ice—leading to
albedo changes (a positive feedback)
Deposition/concentration of particles (soot, dust) on to snow and
ice—also changes albedo
Changes in arctic clouds, slowing heat loss
Changes in meridional circulation patterns—more heat transported
from low latitudes to poles

14. NOAA
Effect: changing Arctic Ocean albedo (feedback)
Impact: disruption of hunting patterns

15. Hysteresis
Tipping point
THE POSITIVE SEA ICE FEEDBACK—ENERGY BUDGET

16. Ice present in summer
No ice in summer
Tipping point
Two very different states of the Arctic – depending
on sea ice nsidc

17. Ice liquid water
BBC; Stanford university
THE BIG THAW
Thawing of ice sheets and glaciers—a consequence of
warming and a cause (water on ice, dust concentration)

18. photo Katey Walter
CHANGING SEASONS:
Timing of thaw on rivers and lakes

19. NASA’s terra satellite
Remote sensing of arctic lake ice-out
through time
Tereza Šmejkalová, Jadunandan Dash, Mary Edwards
2016
13-yr MODIS -- 250 m resolution

20. Once the snow begins to melt and the river and lake ice goes out, travel across
country becomes much more difficult, whether traditional or mechanized
Pinterest.com – Inuit hunter
Once the snow begins to melt and the river and lake ice goes out, travel across
country becomes much more difficult, whether traditional or mechanized
The Koyukuk Winter Road
Wikipedia

21. US Arctic Research
Commission 2003
TERRESTRIAL
PERMAFROST

22. US Arctic Research
Commission 2003
Active layer
Seasonal
thaw
Permafrost
Continually
frozen
As the mean
annual
temperature
increases, a
greater depth
of soil is
exposed to
temps > 0ºC
in summer
PERMAFROST—
permanently frozen
ground

23. NASA’s MODIS/AVHRR-based NDVI (normalized difference
vegetation index) change from 1982 to 2011
ARCTIC GREENING

25. Satellite-observed
greening 1981–2005
in Siberia correlates
with qualitative
observations by
nomadic Nenets
reindeer herders of
recent increases in
willow shrub size.
Forbes et al 2010 Global
Change Biologyphoto Bruce Forbes

27. ICE-WEDGE THAW
In frozen ground, ice tends to segregate into a
polygonal pattern of vertical wedges
Thawing leads to surface water and pond formation
1-2 m
Frost
cracks
Ice
wedge

28. DEEP ICE, DEEP
THAW
Siberian yedoma
Unconsolidated
silt deposits up
to 40 m deep
Ice wedges form
3-D matrix – the
cheese of Swiss
cheese
Up to 80% ice

29. 10->30 m
Syngenetic ice-wedge growth, where substrate
accumulates over time (e.g., loess)
ice
Soil: particles, air,
water/ice

30. 40-m thermokarst amphitheatre, Kolyma River, Siberia
Baydjarakhs syngenetic ice wedges

31. Thermokarst (thaw) lakes in
yedoma: L- in Eastern Siberia;
R- Seward Peninsula, Alaska
Photo: Katey Walter
IKONOS image: Guido Grosse

34. Beaver Creek
River
gravel
Loess
with large
ice
wedges
Soil, active
layer

35. LiDAR imagery (USGS)
1 km

36. Much of the thermokarst occurred just after the end of the ice age,
before the forest returned to Alaska – response to the post-glacial
warming.
The thick forest and mossy ground cover insulate the ground and slow
warming
Hysteresis works to slow permafrost thaw in the Yukon Flats
But……

37. Josh
Rose
The landscape is still active
and fires are linked to lake
drainage

38. Weather underground; IPCC
- Glacial melt contributes to sea-
level rise
- Retreat of sea ice increases wave
exposure

39. Chris Arp USGS
Coastal retreat, northern Alaska.
At the coast, exposed ice-wedges
rapidly thaw and the coast edge
collapses into the sea

40. Benjamin Jones – USGS – old cabin on arctic coast, Alaska (Jones et al. 2008, Arctic)Benjamin Jones – USGS – old whaling boat on arctic coast, Alaska (Jones et al. 2008, Arctic)

41. Thaw and coastal retreat threaten settlements

42. Shishmaref: (Gabriel Bouys/AFP/Getty Images)
Kivalina, Alaska. ShoreZone/Flickr; Alaska DOT
Estimates for moving Kivalina
have been placed between 100
and 400 million dollars.

43. • Warming is
occurring fast in
the Arctic
• Changes are
affecting local
lifeways and big
business
• Alaskan coastal
villagers may be
the first US
communities
displaced by
warming and sea-
level rise
• Feedback
processes can
enhance but also
impede warming
and its effects