Download PowerPoint Presentation - Polar and Arctic ecosystems

Impact of Climate
Change on PeriGlacial
Environments
Arctic(a) vs. Antarctica
 land: 8 X 106 km2
(30% ice)
 land: 14 X 106 km2
(97% ice)
\ substantial
\ no terrestrial food
\ land mammals
\ herbivorous &
\ no land mammals
\ no herbivorous or
terrestrial food
insectivorous
birds (high
diversity)
insectivorous birds
(low diversity)
Tundra ecosystems
“tundra” = treeless barrens
Global distribution of tundra
Arctic ecosystems in Canada
N.Arctic = polar desert
S.Arctic = tundra
Tundra ecosystems
 Tundra ecosystems are associated
with areas of extreme near-polar
climate which operates either
directly, or through a series of
environmental forcings (primarily
thaw-layer dynamics) to limit
productivity and biodiversity.
Tundra climate stations
Barrow
Tiksi
Churchill
Iqaluit
Gulf Stream
Svalbard
Frost-free days
Treeline
Mean annual snowfall (mm)
Treeline
Permafrost
distribution
Alaska
Siberia
Jan
120
150
150
tree
growth
pollen/seed
viability
July
mean location
Polar Front
30
mean #d >10°C
60
frost-free days
240
Boreal forest
patchy discontinuous
mean #d <0°C
Tundra
continuous
Permafrost
Animal life
Climate
change
Hockey Stick - Earth’s Temperature Variations: Past 1000 Years
Source: Arctic Climate Impact Assessment website
Associated Climate Changes
• Global sea-level has increased 1-2
mm/yr; in 80 years a rise in sea level
between 3.5 and 34.6 in. (up to 3ft) is
expected
• Duration of ice cover of rivers and lakes
decreased by 2 weeks in N.
Hemisphere
• Arctic ice has thinned substantially,
decreased in extent by 10-15%
• Reduced permafrost in polar, subpolar, mountainous regions
• Growing season lengthened by 1-4
days in N. Hemisphere
• Retreat of continental glaciers on all
continents
• Snow cover decreased by 10%
(reduced solar reflection)
Source: Intergovernmental Panel on Climate Change, 2001 Report
79, the size of the summer polar ice cap has shrunk more than 20 pe
Recent (post-1950) climate
change in polar regions
Arctic:
•
•
•
•
Reduction in sea ice extent and thickness
Northward treeline shifts (e.g. E. coast Hudson Bay)
Increased lakes, bogs (e.g. Ellesmere Island)
Range expansions (e.g. dragonflies - Inuvik - 2000)
Antarctic:
• Ice shelf disintegration (e.g. N. Larsen & Wordie Shelf)
• Spread of flowering plants (e.g. Antarctic hairgrass has
expanded its range 25-fold since 1964)
• New lichen species colonizing recently deglaciated areas
Polar
AmplificationFeedbacks
• Ice-Albedo Feedback
–relevant to retreating
perennial ice cover and
also over land
• Cloud feedback –
positive or negative,
depending on the
height of clouds
• Other feedbacks are
mainly positive
Total Ice Cover/Monthly Anomalies
From 1978 to 1996,
the trend in the ice
extent was -2.2% per
decade. Since 1996,
the trend has
changed
to -10.1% per decade
suggesting a large
acceleration in the
decline.
Acceleration in the
decline makes it
difficult for ice to
recover because
of ice albedo
feedback.
-10.1%/dec
-10.7%/dec
Permafrost in Alaska