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Climate Change and the Effects on
Tropical Glaciers
Georg Kaser and Mathias Vuille
John Bauchmoyer
Aircraft Systems Major
MODERN GLACIER RETREAT ON KILIMANJARO AS EVIDENCE OF
CLIMATE CHANGE: OBSERVATIONS AND FACTS
Georg Kaser, Dr.
- University of Innsbruck
- Deputy Head of the Institute of Meteorology and Geophysics Innsbruck
- Phone: +43 512 507 / 54457
LONNIE THOMPSON!!!
Mount Kilimanjaro
Africa’s highest peak
Consists of three single peaks
- Shira (4005 m)
- Mawenzi (5140 m)
- Kibo (5893 m)
- only peak to retain glaciers
- summit collapsed to form a 1.9 km by 2.4 km caldera
Research Methods
Design - Observational
Variables of Interest Measured:
● Marked features i.e. penitentites, cliffs and rounded or sharp
edges
● Vertical cliff heights
● Ice mass thinning/ lateral retreat of ice walls
● Seasonal variations of solar incidence
● Thickness of ice on the summit plateau
● Thickness of permafrost
Kilimanjaro Glaciers
Since 1880, recorded strong recession
Thermal homogenous
- vertical ice walls
- recession not due to sensible heat
Kilimanjaro Glaciers
• Air temperature considered most important factor in glacier retreat
globally, not demonstrated in tropics
• Complex combination of:
• air temperature
• humidity
• precipitation
• cloudiness
• incoming shortwave radiation
Kilimanjaro Glaciers
• Decades preceding 1880
• Lake levels were high
• Extensive mountain glaciation
• 1880 and on
• Lake levels dropped notably
• Glaciers began to recede
• Relatively dry climate
maintained throughout the 20th
century
Kilimanjaro Glaciers
•
Lateral retreat of ice walls implies
occurrence of negative mass
balances
•
Ablation tied to seasonality of solar
radiation
•
Low incidence angles during the dry
season
•
Lack of turbulent air flow along
vertical surfaces
•
Minimizes sublimation
Future of Kilimanjaro
• If condition persists, plateau
glaciers will disappear for the first
time in over 11,000 year
• More research has verified the
concept for mass loss due to
sublimation.
• Need more research on mesoscale
modelling and meteorological
measurements.
Climate change and tropical Andean glaciers:
Past, present and future
Mathias Vuille
- Associate Professor in the Department of Atmospheric and Environmental
Sciences at the University of Albany
- M.S. 1991, University of Bern
- Ph.D. 1995, University of Bern
- Phone: (518) 442-4472
LONNIE THOMPSON!!!
Research Methods
Design - Observational
●
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Variables of Interest Measured:
Atmospheric humidity - governs sublimation
Precipitation - variability induces feedback on albedo
Cloudiness - controls incoming long-wave radiation
Air temperature
Andean Glaciers
-
99% of tropical glaciers located in the Andes
-
80% of freshwater supply
- changes in water supply, massive effect on the communities
Andean Glaciers
Observed 20th Century Climate Change
- Temperature
- Precipitation
- Humidity
- Cloud Cover
- Atmospheric Circulation
Andean Glaciers
Temperature
- Temperature increase of 0.15 °C/decade (1950-94)
- Regionally increased 0.35-0.39 °C/decade
Precipitation
- 42 stations
- Most indicated a precipitation decrease
- Only 5 showed a significant change
Humidity
- Increase in relative humidity between 1950 and 1995
- Up to 2.5%/decade
- Prominent positive trend in northern Ecuador and southern Columbia
Follows specific humidity trends due to rising temperatures
Andean Glaciers
Cloud Cover
- Outgoing long-wave radiation
- Constantly monitored by polar orbiting satellites since 1974
- High clouds = low OLR values
- Clear skies = high OLR values
- Significantly decreased from 1975
Atmospheric Circulation
- Intensifying of the Hadley circulation
- Weakening of the Walker circulation
- Shift to more El Nino-like state
Tropical Glacier Mass and Energy
Balance
Fundamentally different from mid- and high-latitude glaciers
Lack of pronounced thermal seasonality
- clear differentiation between wet and dry seasons
Mid-latitude Glaciers
- winter accumulation, summer ablation
Tropical Glaciers
- ablation and accumulation can occur at the same time
Tropical Glacier Mass and Energy Balance
El Nino
La Nina
- strongly negative mass balance
- nearly balanced or even positive
- dry and above average
mass balance
temperatures
- wet and below average
- reduced accumulation and lowered
temperatures
albedo
- increased accumulation and
- low wind speeds
albedo
- increase in incoming short-wave
- consistent wind speeds
radiation
- decreased incoming short-wave
- reduced cloud cover
radiation
- increased cloud cover
Impact for People
Given projected future changes in climate
and glacier mass, negative impacts will
likely be felt.
● change in streamflow due to lack of
glacial buffering during the dry season
● availability of drinking water*
● availability of water for hydropower*
(major source of electricity in most
Andean countries)
● availability of water for mining* and
irrigation*
*further aggregated by growing population
and increasing water demands
Greater collaboration and
integration between
agencies.
Should not be limited to
scientists but needs to
include local stakeholders
and decision makers.
Scientists need to provide
information that is not only
scientifically relevant but also
socially applicable.
Opinion on Future Research
AWS’ need to be placed in more diverse locations
Focused studies on the climate change in abnormal topography
More research is needed in general to protect the livelihood of the
communities affected by tropical glaciers
Questions?