Transcript Cryosphere changes

CRYOSPHERE CHANGES
• These slides show photographs and images so
that you can learn about how the cryosphere
is being affected by climate change today.
• You can refresh your knowledge of what is
meant by the ‘cryosphere’ by visiting the
Discovering The Arctic website:
http://www.discoveringthearctic.org.uk/9_wh
at.html
Collapse of West Antarctic ice shelves: Larsen B, bigger than the
US state of Rhode Island (or Cornwall), disintegrated in 2002.
Satellite
image
http://commons.wikimedia.org/wiki/File:Larsen_B_Collapse_Size_Co
mparison.png Robert A. Rohde
See the next slide for the former location of this ice shelf.
NASA satellite infrared sensor data: this shows the
pattern of warming across the snow, ice, and sea
surfaces in the Antarctic region from 1981 to 2007.
http://commons.wikimedia.org/wiki/File:Antarctic_Temperature_Tren
d_1981-2007.jpg
The ‘0’ here refers to the average temperature
over the time of recordings.
http://scienceblogs.com/significantfigures/index.php/2013/04/02/thre
e-iconic-graphs-showing-the-climate-fix-were-in/
20th century global average temperature rise of about 0.7ºC. In parts of West
Antarctica and the Arctic, temperature has risen by over 3°C in the last 50 years.
Each year Arctic sea ice reaches its lowest extent in September
(by end of the summer). Notice how this trend compares with the
temperature trend in the previous slide.
http://nsidc.org/arcticseaicenews/2013/10/
The white area of the map shows Arctic sea ice extent
in September 2013. The magenta line around it shows
the 1981 to 2010 median.
http://commons.wikimedia.org/wiki/File:Arctic_ice.jpg?uselang=en-gb
Patrick Kelley
Photo showing break up of sea ice.
North Pole
Greenland ice sheet
http://nsidc.org/arcticseaicenews/2013/10/
In addition to becoming less extensive, Arctic sea ice has become
thinner and will continue to thin this century.
NOAA image
http://commons.wikimedia.org/wiki/File:Arctic_Ice_Thickness.png?us
elang=en-gb
View of Mont Blanc, near Chamonix, France. Since AD 1850 the
total area of the Alps covered by glacier ice has halved.
http://commons.wikimedia.org/wiki/Chamonix#mediaviewer/File:Mont_Blanc_100
_0068.JPG (Daniel D.)
Melting glacier images
1938-2009 comparison: Grinnell Glacier, Montana, USA.
http://commons.wikimedia.org/wiki/File:Grinnell_Glacier_19382009.jpg?uselang=en-gb (T.J.Hileman 1938, Lindsey Bengtson 2009)
Melting glacier images
Interior of
Greenland
is on this
side.
NASA
image
The sea is
on this side.
Retreat of the calving edge of the Jakobshaven outlet glacier,
Greenland, between 1851 and 2006.
http://commons.wikimedia.org/wiki/File:Jakobshavn_retreat-18512006.jpg?uselang=en-gb
Melting glacier images
1941-2004 comparison: Glacier Bay National Park and Reserve's
White Thunder Ridge (Alaska) as seen on August 13, 1941 (left)
and August 31, 2004 (right). Muir Glacier has retreated out of the field of
view, Riggs Glacier has thinned and retreated significantly, and dense new
vegetation has appeared. Muir Glacier was more than 2,000 feet thick in 1941.
2004 USGS photo by B. F. Molnia; 1941 photo by W. O. Field.
http://nsidc.org/cryosphere/sotc/glacier_balance.html
Melting glacier images
Kenai Fjords National Park, Alaska. This glacier still exists but has retreated 20 km back
from the 1909 position and is out of view in the 2004 photo.
http://commons.wikimedia.org/wiki/File:McCarty_Glacier.jpg?uselang=en-gb Ulysses S. Grant 1909, Bruce
Molnia, 2004)
Melting glacier images
http://commons.wikimedia.org/wiki/File:Snow_and
_Ice_on_Kilimanjaro-1993.jpg?uselang=en-gb
http://commons.wikimedia.org/wiki/File:Snow_and
_Ice_on_Kilimanjaro-2000.jpg?uselang=en-gb
1993-2000 comparison: Over 80% of the ice and snow on Mount Kilimanjaro,
Tanzania, has disappeared over the past century, much of it in the past few
decades (NASA Landsat 5 images).
This map shows changes to glacier mass balance in mountain regions
between 1970 and 2004. Notice the anomaly of Scandinavia which has some
glaciers that thickened during the time period of measurement.
83% of the
surveyed
glaciers
showed
thinning.
New Zealand
http://commons.wikimedia.org/wiki/File:Glacier_Mass_Balance_Map.
png (Robert A. Rohde)
Map of temperature rise across Antarctica from 1957 to 2006.
East
Antarctic
ice sheet
West
Antarctic
ice sheet
http://commons.wikimedia.org/wiki/File:AntarcticaTemps_19572006.jpg?uselang=en-gb NASA image
Notice from the colour difference how West Antarctica is being affected by more warming
than East Antarctica. Much of East Antarctica has experienced little, if any, change.
Some clues for understanding why the West
Antarctic ice sheet is more sensitive to climate
change than the East Antarctic ice sheet
• The East Antarctic Ice Sheet (EAIS) has about 9 times
the volume of the West Antarctic Ice Sheet (WAIS)
• The EAIS has an average thickness of 2,226 metres
compared with the WAIS maximum of 1,306 metres.
• The EAIS reaches a higher elevation above sea level
(over 4,000 metres) than the WAIS.
• In contrast with East Antarctica, the WAIS sits on
bedrock that is mostly below sea level.