Observations: Cryosphere
Cryosphere: the components of the Earth System that
contain a substantial fraction of water in the frozen state
The cryosphere comprises several components: snow, river
and lake ice; sea ice; ice sheets, ice shelves, glaciers and ice
caps; and frozen ground which exist, both on land and
beneath the oceans
Synthesis
The Cryosphere in Numbers
SEA ICE
Arctic Sea Ice – Facts
• Passive Microwave Satellite Retrievals
continuously since 1979
• ‘Sea Ice Extent’: The sum of ice covered areas
with concentrations of at least 15%
• ‘Sea Ice Area’: The product of the ice
concentration and area of each data element
within the ice extent
• Summer ice only in: (i) Arctic Ocean Basin, (ii)
Canadian Arctic Archipelago
• Minimum sea ice extent at the end of summer
(September)
The Shrinking Arctic Sea Ice
The Shrinking Arctic Sea Ice
• The 34-year record shows an accelerating
shrinking trend in sea ice extent, most
pronounced at the end of summer
• NH Trend autumn: - 7.0± 1.5% per decade
• NH Trend spring: - 1.8± 1.5% per decade
• Particularly large negative trend for multi-year
ice: - 14.7± 3.0% per decade
• Also ice thickness shows a systematic downward
trend: - 0.6 m per decade (Arctic Ocean)
Arctic Sea Ice Extent / Area from
Satellite Microwave Sensors
What happened in the summers of 2007 and 2012?
Arctic Sea Ice Extent 1870 - 2011
Combining:
- Various in situ sources 1870 – 1978
- Satellite data 1979 - 2011
Arctic Sea Ice Thickness Trends
Arctic Sea Ice Drift
• Sea Ice Drift increased by + 17± 4.5% per
decade in winter and + 8.5± 2.0% per decade
in summer from 1978-2007 (buoy data)
• There was no trend in wind speed in that time
period (atmospheric reanalyses)
• Interpretation:
• Weaker and thinner ice cover
Ice Season Duration
• Most rapid change in East Siberian Sea / West
Beaufort Sea
• Onset in autumn: Sea ice advance 41± 6 days
later in 2011 than in 1979
• Melt in spring: Sea ice retreat 49± 7 days
earlier in 2011 than in 1979
• I.e., the summer ice-free season became 90±
16 days (3 months) longer over the 32-year
period
Arctic Sea Ice: Linear Decadal Trends
Arctic Sea Ice: Linear Decadal Trends
Arctic Sea Ice: Linear Decadal Trends
How about the Antarctic Sea Ice?
Sea Ice
constrained
to latitudes
north of 78°S
Antarctic Sea Ice: Not shrinking!
In what sense is Antarctic Sea Ice
different in nature?
• Mostly first-year ice
• Why?
• Thinner, warmer, more saline, more mobile
than the Arctic sea ice
• Remote sensing more difficult
• Manual observations few due to remoteness
Antarctic Sea Ice Extent
• Increasing by +1.5 ± 0.3% per decade, most
pronounced in autumn (+3.0± 2.0% per
decade)
• Even higher trends for sea ice area (+1.9±
0.7% per decade), indicating …….?
• Less open water, indicating …..?
• Possibly due to less storminess and divergence
Regional Variations in Antarctic Sea Ice
Changes
• Sea Ice Drift: (1) Acceleration of the wind
driven Ross Gyre; (2) Deceleration of the
Weddell Gyre
• Ice Season Duration near the Antarctic
Peninsula: - 100± 39 days over 1979 - 2010
• Ice Season Duration western Ross Sea: + 79±
12 days over 1979 - 2010
Comparison Arctic vs Antarctic
GLACIERS
The World’s Glaciers
Areas covered by Glaciers
Changes in Glacier Length
Changes in Glacier Length
How rapidly are the glaciers shrinking?
Regional Glacier Mass Budgets
Regional Glacier Mass Budgets
Regional Mass Change Rates
Glacier Mass Change
Last 210 years
Last 50 years
Mountain Glaciers
ELA= Equilibrium Line Altitude
(for a given climate)
Glacier Melting and Sea Level Change