1. Introduction
To explore the opportunities for research
on climate variability in the Americas from high elevation ice cores, a
group of 20 scientists representing 11 countries met in San Carlos de Bariloche,
Argentina from 11-13 December, 1996. (participant
list with group photo) Discussions focused on regions of the Americas
from which additional ice core records could be recovered, and the value
of each location in terms of understanding climatic variability. The geographical
scope of the workshop discussion extended from the Antarctic Peninsula
(~ 74°S) to northern Ellesmere Island (83°N). The meeting was financially
supported by the Inter-American Institute for Global Change Research (IAI).
The primary goals of the workshop were to identify both the principal scientific
questions which can be answered, and societal issues which can be addressed,
by ice core studies along a North-South transect through the Americas,
to determine which ice caps have the potential of yielding high resolution
paleoenvironmental records, and to initiate discussions on programs of
collaborative research.
The first session of the workshop was devoted to
presentations reviewing the current state of knowledge in three areas:
1. Circulation regimes of South America and meteorological observations
at high elevation;
2. Methodological techniques and issues of ice core analysis; and
3. Regionally-specific research accomplishments related to glacier-climate
interactions and ice core drilling in the Americas.
Discussions were then conducted as a group on individual regions of
the Americas where there are excellent prospects for recovering paleoenvironmental
records from ice cores. On the third day, we split up into small groups,
each with a regional focus, to discuss specific needs and ideas for research
projects in each region. The group then came together once again to hear
summary presentations from the small groups and discuss integration of
the projects into a coordinated proposal.
2. Rationale
Whatever anthropogenic effects on climate occur
in the future, they will be superimposed on a background of natural climatic
processes which may mask, or magnify, such impacts. To understand and anticipate
what lies ahead, or even to understand our contemporary environment, requires
an assessment of conditions which preceded the present, a perspective which
can only be gained by studies of the past. Such research focuses on both
the time-evolution of relevant processes (which may operate on time-scales
from many millennia to a few decades) and on their interactions through
time. This may shed light on the linkages between biogeochemical processes
and the physical aspects of climate, enabling causes and effects to be
isolated and assessed. Studies of the past also reveal how quickly earth
systems have responded to particular forcing factors, which is of critical
importance in anticipating and planning for future environmental changes.
Finally, a better understanding of environmental conditions in the past
is invaluable for testing numerical models of atmospheric and oceanic circulation,
biospheric dynamics and environmental processes, by providing a database
of environmental conditions in the past which were quite different from
those of today (Bradley and Eddy, 1991).
Climatic variations of the last 2000 years are of
particular relevance to contemporary human endeavors. Although climatic
fluctuations over this time period were small in comparison with those
expected from a doubling of greenhouse gases (e.g. generally <2°C
in decadal mean, seasonal anomalies for any one region, versus 4-8°C
expected in the 21st century) the last 2000 years have witnessed the most
extreme conditions of the Holocene period. Furthermore, there is abundant
evidence that even such relatively small climatic anomalies have had significant
impacts on human societies, for example, as a result of prolonged droughts,
and other climate-related disruptions (Thompson et al., 1988). We must
understand these fluctuations and their causes (forcing mechanisms) and
the interactions (teleconnections) between one region and another because
it is on this background of natural variability that the anthropogenic
greenhouse effect is being imprinted. Instrumental records are too short
to provide the necessary perspective. Only climate-related "proxy" records
can provide the longer time frame necessary to document the significance
of underlying trends, to analyze the nature of any periodicities in climate,
and to address the critical issue of "abrupt" climate change (Thompson
and Mosley-Thompson, 1987). Temperatures today are higher than they were
in the late 19th century, but we can not yet say definitively how much
of the observed warming is due to natural oscillations of climate, and
how much is related to human activities (Bradley and Jones, 1995). Long-term,
high resolution proxy records from poorly-studied regions of the world
(e.g. Latin America) are an essential pre-requisite to placing contemporary
climatic conditions in perspective, and constructing a globally comprehensive
view of climatic variations in the past.
Ice cores provide excellent, high-resolution records
of past environmental conditions and climatic variability. Along the western
margin of North and South America are a nearly continuous series of ice-capped
or glacierized mountains, containing a unique archive of information. Annual
layers of precipitation record the atmospheric processes involved in moisture
transport to the ice caps (e.g. Grootes et al., 1989); particulates and
dissolved material deposited with the snow document atmospheric constituents;
gases trapped in the ice record past atmospheric composition. Geochemical
studies of ice cores provide a comprehensive view of prevailing air masses
and of atmospheric circulation in the past (e.g. Mayewski et al., 1993a).
Some of the most important discoveries about earth system processes have
been obtained from ice cores from high latitude ice sheets (e.g. Jouzel
et al., 1989; Dansgaard et al., 1993; Taylor et al., 1993). However, these
studies can not address fundamental questions of significance to lower
latitudes; in particular, climate variations related to ENSO are of great
significance in the Tropics, accounting for much of the variance in temperature
and precipitation in this region (e.g. Bradley et al., 1987). Ice cores
from low latitudes generally have high accumulation rates, providing high
resolution, direct records of precipitation and temperature changes due
to ENSO (Thompson et al., 1984a, 1985). Together with other proxy records,
long-term changes in ENSO variability can be assessed (Baumgartner et al.,
1989). The importance of long-term data on ENSO from paleoclimatic time
series was explicitly recognized by participants in the IAI Workshop on
ENSO and Inter-annual Climate Variability (IAI, 1995). Additional ice cores
from low latitudes of the Andes should help in further documenting past
ENSO activity, by constraining uncertainties in the few existing records.
No other high resolution proxy records of past climate are yet available
for the inter-tropical Americas.
ENSO variability is not the only important quasi-periodic
variation observed in long-term climate records. Recent studies have demonstrated
that lower frequency variations (10-20 years), possibly associated with
other large-scale climate systems (such as the "Pacific-North America"
or PNA circulation mode) play a role in decadal-scale climate variability
in the extra-tropical regions of the Americas (Mann et al., 1995). By obtaining
more high resolution ice core records along the western axis of the Americas,
from low to high latitudes, it should be possible to shed further light
on this aspect of climate variability, and to what extent these are linked
to lower frequency aspects of the ENSO system.
Recent observations have clearly documented the
urgency of recovering ice cores from high altitude sites in the tropics.
Ice caps and glaciers in the region are rapidly melting and retreating,
at a rate that threatens to destroy unique paleoenvironmental records (Hastenrath
and Kruss, 1992; Schubert, 1992; Thompson et al., 1993). Freezing-level
heights have been rising at low latitudes, apparently in response to decadal-scale
changes in tropical sea-surface temperatures (Diaz and Graham, 1996). There
is also the suggestion, based on general circulation model experiments,
that high elevations in the Tropics may be particularly vulnerable to greenhouse-gas
induced warming (Mitchell et al., 1990), providing additional pressure
to develop a coordinated, international high altitude ice core research
program. At the same time, models project that high latitudes will ultimately
witness the largest changes in temperature. A transect of ice cores from
high southern latitudes (Chile/Argentina) to high latitudes of the northern
hemisphere (Alaska/Yukon Territory) would provide a valuable perspective
on the underlying climate variability throughout the Americas, and on inter-hemispheric
linkages in the timing and mechanisms of climate change, at a time when
greenhouse gases are rising exponentially.
3. Region-specific Workshop discussions: promises &
prospects
At the workshop, five regions of the Americas where
new ice core records might be obtained were delineated, as a framework
for discussion:
· Antarctic Peninsula
· Patagonian Icefields
· Andean ice caps and glaciers between the Patagonian Icefields
and the Dry Axis
(~ 46° to ~28°S)
· Inter-Tropical Zone
· High latitudes of North America.
Group discussions concentrated on the scientific questions that could
be addressed by ice cores from each region. Previous ice core, glacier,
and climate research within each region was also discussed, including geophysical
surveys, short ice cores, mass balance programs, and meteorological data.
In addition, the group attempted to address the uncertainties, special
considerations and/or issues unique to each region. These discussions were
designed to provide the background for development of strategic recommendations.
3.1 Antarctic Peninsula
The Antarctic Peninsula begins less than 1,000 km
from southernmost South America, and extends south from ~ 62°S, to
where the peninsula merges with the continent at ~ 74°S. There are
major ice shelves adjacent to the Peninsula, the break-up of which would
have global implications. Indeed, the demise of several minor ice shelves
(Doake and Vaughan, 1991; Rott et al., 1996) supports predictions about
the climatic sensitivity of ice shelves on the Peninsula (Mercer, 1978),
and has created a sense of urgency to understand past climate variability
on the peninsula (cf. Fahnestock, 1996). Several existing ice core records
(see for example Aristarain et al., 1990; Peel, 1992) have already been
helpful to the understanding of climatic variability in the region. These
records may also contain evidence for ENSO variability in the past. In
addition, due to the oceanic proximity, records from the peninsula are
likely to contain an important record of marine biological activity, as
existing ice core records and the University of São Paulo aerosol
sampling program has shown. Ice cores have also produced information about
local volcanism (Aristarain et al., 1982).
Considerable data collection is currently being
conducted on the peninsula, relative to the other potential regions the
group considered. For example, in the Antarctic Peninsula region there
exist the oldest and largest number of meteorological stations. Also, the
British operate at least five automated weather stations (AWS) and seven
are operated by the North Americans (University of Wisconsin; only two
of these are at elevations above 100 m: ‘Uranus Glacier’ at 780 m and ‘Ski-Hi’
at 1395 m). From these data and the manned stations, it is known that there
are large east-west gradients of temperature and precipitation, which will
complicate the spatial extrapolation of results from single ice-core sites.
In 1997, an Argentine-French project on the Peninsula will commence drilling
to a planned depth of 300 m, which will hopefully cover 2,000 years.
Despite the prior and on-going work on the Peninsula,
discussion emphasized that additional efforts will be required to understand
the isotopic signal in the cores. This would involve increased sampling
of precipitation, and experiments tracing the isotopic concentration of
the snowpack through time. The AWS data will require careful analysis to
explore variability in precipitation source area, which seems likely given
the oceanic proximity and interannual variability in sea-ice cover. Meteorological
modeling support would be essential to working with these data, and the
Brazilian group has begun such efforts.
3.2 Patagonian Icefields
The North and South Patagonian Icefields are two
relatively narrow ice masses stretching 100 and 360 km, respectively. The
North Patagonian Icefield (NPI) is approximately one-third the total area
of the South Patagonian Icefield (SPI), and the mean surface elevation
is approximately 500 m lower (Warren and Sugden, 1993).
Ice core records from Patagonia would provide basic
information on precipitation at high elevations in the southern Andes,
about which very little is known. The combined latitudinal extent of the
two icefields provides an opportunity to investigate changes in the position
and strength of westerly airflow through time. As on the Antarctic Peninsula,
there is a strong east-west climatic gradient across the icefields, the
strength of which has also probably varied through time. Ice cores from
a network of carefully selected sites could help resolve both of these
questions.
A limited number of investigations have been carried
out on the accumulation areas of the icefields (e.g. Yamada, 1987; Aristarain
and Delmas, 1993), despite considerable recent work by Naruse, Skvarca,
Aniya, Casassa and others on the marginal position (extent) and thickness
changes of Patagonian glaciers. This work in the ablation areas indicates
that most NPI and SPI outlet glaciers have been retreating (Aniya, 1988;
Aniya et al., 1992; Naruse et al., 1995), although others such as the Moreno
Glacier seem stable (Skvarca and Naruse, 1997). Measured surface lowering
rates in the region, such as 10-15 m/yr for the Upsala Glacier in the early
1990s, are among the highest in the world (Naruse et al., 1997). In the
accumulation areas, Casassa has recently had a student working on the Chico
Glacier (SPI, north of Fitzroy), and Naruse has been overseeing work on
the NPI accumulation area which has included a 14.5 m deep firn drilling
at 1500 m a.s.l. in December 1996. They, a team of Japanese graduate students,
failed in radio echo sounding, because an oscilloscope placed on a sledge
was blown away by winds!
Patagonia presents at least three special conditions,
relative to ice core drilling. First, the region is relatively warm. Using
measured temperatures at low elevation and assumed lapse rates Naruse estimates
that the 0°C maximum temperature level is ~ 2500 m, which is higher
than most of the accumulation areas. Melting, and ice layers, are therefore
to be expected in any core from the region. Second, the high precipitation
on the icefield suggests that very deep drilling will be required to extend
the ice core record back a reasonable time, however, net accumulation rates
are also unknown. In one location — at 2680 m in the accumulation area
of several large glaciers in the SPI — a 13 m core indicated an accumulation
rate of only 1.2 m/yr water eq. (Aristarain and Delmas, 1993), although
Naruse et al. (1995) estimate that 6-8 m of accumulation in water should
be required to support the Moreno Glacier. Lastly, field work in the region
is extremely difficult, due to wind and precipitation. Aniya et al. (1996)
note that nearly cloud-free images from three adjacent Landsat scenes are
available for only one day in nearly 25 years of data!
The dearth of field work in the accumulation area
suggests a need for reconnaissance geophysical surveys, short cores recovered
from the highest elevations, and installation of AWSs. Geophysical work
could provide a picture of basic bedrock topography as well as the glaciological
information currently lacking, which will be necessary to select the best
drilling sites. However, any geophysical techniques employed must be capable
of dealing with liquid water within the glaciers, possibly even at the
highest elevations. One drill hole made at 1300 m on the San Rafael Glacier
to 38 m contained a two-meter thick aquifer on the firn-ice interface at
about 25 m in depth (Yamada, 1987). Due to the high accumulation rate on
the icefields, there is a need for a network of medium-length cores (~
50 m), which must be drilled with lightweight, portable equipment suitable
for use in the remote location. This effort would provide a useful indication
of spatial variability in isotopic and geochemical concentrations, and
allow measurement of temperature profiles. Detailed east-west and north-south
transects of short, hand-drilled cores should also be considered prior
to efforts to select new deep drilling sites. Although there are some meteorological
station data from locations such as Lago Argentino (1940 to present) and
Punta Arenas (1870 to present), the sharp climatic gradients in the region
render these data difficult to extrapolate spatially; Naruse has measured
such a sharp gradient over a distance of only 60 km (Takeuchi et al., 1996;
Naruse et al., 1997).
3.3 Patagonia to the Dry Axis
Important glacierized zones extend along the Andes
from north of the NPI to Cerro Potro (~28°S, 5864 m), the most northerly
massif that is out of the Dry Axis. Included among these is the 300 km2
Aconcagua massif (~ 33°S; 6960 m). This region also contains numerous
active volcanoes which are concentrated between 32 and 42°S. Glaciers
and rock glaciers are very important in the region as water resources,
particularly on the drier eastern side (Argentina). These mountains come
under strong influence of westerly circulation during the winter, resulting
in a sharp west to east precipitation gradient (as in Patagonia). In contrast
to mountains north of the Dry Axis, the principal moisture source for glaciers
is from the Pacific Ocean to the southwest. Ice core records from suitable
sites are likely to contain a strong ENSO signal.
Previous meteorlogical observations have occurred
on Maipo (34°S and 69°50’W; 5200 m), where a weather station existed
at 3700 m for a few years, allowing an estimated maximum temperature of
-9°C to be calculated for a potential drill site at 5200 m. Near Tupungato
volcano (32°20’S and 69°45’W; summit at 6550 m), where a mass balance
study has been carried out by Escobar since 1975, a few potential drill
sites exist at ~ 5,000 m, where the estimated mean annual temperature is
about -11°C. One of them, a glacier on the "Mesón San Juan"
mountain (~33°33’S and 69°46’W, 6035 m), was approached by Aristarain
in March, 1997 with drilling equipment. Unfortunately, it was not possible
to accomplish the mission due to large penitentes and crevasses not found
in previous years. Further north, there is another potential drilling site
on Co. Tapado (5536 m, 30°08'S, 69°56'W) in the Elqui Valley. Compared
to a weather station at 3100 m, the estimated mean annual temperature is
between -7 and -8°C, while the 0°C isoline is situated at 4300
m. The Co. Tapado and the Co. Potro site will probably be tested with short
ice cores during summer 1997/98 (University of Bern, SNF project).
There are very local climatic effects around the
existing meteorological sites in the region, Aristarain reported. As a
result, temperature estimates may be in error, and some sites may not be
high enough in elevation to avoid significant meltwater percolation. (Indeed,
a d18O elevational profile made by Holdsworth, from
snow samples he collected en route to the summit of Aconcagua, suggests
that coring there would have to be done above 6200 m, if an ice
cap existed.) At other sites, particularly those that are not ice caps,
there may be flow disturbance to the glacier stratigraphy induced by underlying
topography. This would limit the useful length of any records recovered.
3.4 Tropics
Potential ice core drilling sites exist in the inter-tropical
region between Nevado Sajama (18°S) just north of the Dry Axis, and
the equatorial volcanoes of Equador. There is a great need to explore these
sites for new records, as throughout the region glaciers are retreating
(e.g. 160 m at Antisana this century) and evidence from multiple sources
indicates that freezing-levels are rising in the tropics (Diaz and Graham,
1996). Water resources will become increasingly important in the region.
The scientific questions that could be addressed
by additional ice cores from the tropics are numerous, as demonstrated
in previous coring efforts by Thompson. Potential sites for long records
are relatively abundant. Questions that could best be addressed by a network
of records include:
3.5 North America (Canada and Alaska)
Discussion of potential sites within this vast region
concentrated on the St. Elias Mountain Range on the border between Alaska
and the Yukon Territory, the Alaska Range of interior Alaska, and the ice
caps of the Canadian Arctic Archipelago, within the Nunavut region. The
potential and existing Alaska-Yukon ice core drilling sites are relatively
high elevation (e.g. Mt. Logan at 5330-5340 m), and most are located just
south of the Arctic Circle (e.g. Mt. Logan at 60.5° N). The climate
at these sites is severe, as evidenced by a 10 m temperature of -29.5°C
recorded in the PR col between sub-peaks of the Mt. Logan massif (PR col
refers to that between Prospectors Peak and Russell Peak). The northern
Canada (Nunavut) sites are at considerably higher latitudes (75° to
83°N) and all are less than ~ 1700 m elevation. As a result of these
differences in geographic location and elevation, the scientific questions
that the two regions can address differ somewhat.
Although the airflow is predominantly westerly in
the Alaska-Yukon region, and air masses of maritime Pacific origin are
dominant at low elevations to the south and west of the mountain ranges,
the potential ice core drilling sites are above the level of both marine
and continental aerosol influence (Holdsworth and Peake, 1985). As a result,
the geochemical signals in the ice core records should be reflective of
mid-tropospheric atmospheric composition. These sites thus record background
atmospheric dust levels, due to their isolation from local sources (Mayewski
et al., 1993b). Indeed, there was no anthropogenic SO4- 2 signal in the
Mt. Logan core (Monaghan and Holdsworth, 1990). Additional aspects of climate
variability that could be addressed at Alaska-Yukon sites include the Pacific-North
America circulation (PNA) pattern and the influence of ENSO on precipitation.
Due to the prevalence of active volcanoes, particularly in the Aleutian
Islands and north Pacific rim, these ice cores have the potential for excellent
chronological control (cf. Holdsworth and Peake, 1985).
There have been two deep (> 100 m) ice cores recovered
in the Yukon: at 5,300 m on Mt. Logan in 1980 (G. Holdsworth, 103 m; adjacent
cores of 46 and 51 m), and at ~3000 m on Eclipse Dome in the St. Elias
Range in 1996 (E. Blake, 160 m of possible 500 m depth). The Mt. Logan
record covers ~ 300 years, at a site where net annual accumulation (snow)
is ~ 1.1 m. The record from the Eclipse site contains a higher proportion
of melt layers, due to the lower elevation. This site has a 2-year meteorological
record. There have been other short to medium-depth drilling efforts in
the region, including a 40 m core from Mt. Wrangell in Alaska taken in
1984 (although this was strongly contaminated by H2SO4).
At potential ice core sites in the Alaska-Yukon
region, geophysical surveys will be especially important prior to selection,
because of glacial flow considerations. Topographic relief is high, and
these glaciers have a high mass turnover, requiring a large flow divide
area to obtain ice which is not sheared at depth. Topography greatly influences
the distribution of precipitation as well, because high velocity winds
create areas of scour and deposition. Snow accumulation at potential sites
must be representative as possible of regional precipitation, despite variability
of wind direction.
The northern Canada ice cores have been especially
useful in the reconstruction of summer temperatures, through the analysis
of melt proportions (Koerner, 1977). From the isotopic composition, mean
annual temperature has also been estimated. Microparticle and the concentration
of different chemical species provides information about high latitude
atmospheric composition. Ice cores from the most northerly of the potential
sites could also provide a valuable record of sea-ice cover on the Arctic
Ocean. Although most sites suitable for ice core recovery experience melting
during the summer, there may be localized cold sites where the records
will be less influenced by meltwater percolation.
Ice core drilling in the Canadian High Arctic began
with the Meighan Ice Cap in 1965, the record from which consisted mainly
of superimposed ice due to excessive melt, and which primarily reflected
local conditions. The Devon Island Ice Cap was drilled in 1971 (as well
as 1972 and 1973), and provided a record extending back > 100 kyrs that
is well correlated with the records from Greenland. Another effort to recover
a pre-industrial revolution record from Devon Island is planned for the
spring of 1997. On the Agassiz Ice Cap of Ellesmere Island, six cores to
bedrock have been drilled since 1977 (all between 1670 m (A77) and 1730
m (A93)). While the record from the summit was excessively affected by
wind scour, another site 1 km lower has provided an excellent record. Two
different sites have recently been drilled on the Penny Ice Cap of southern
Baffin Island (333 and 180 m), and these cores are currently being analyzed.
There is a need for additional spatial sampling
surveys in both regions, to assess how variable the isotopic signal is.
Such a program will be undertaken on the Devon Ice Cap this year in conjunction
with the drilling. Meteorological monitoring is also needed at high elevation
sites in these regions, as the only existing stations are on the Agassiz
and Penny Ice Caps. The extreme winds and high snowfall will provide serious
impediments to the operation of such stations in the Alaska-Yukon region.
For example, at the PR col site on Mt. Logan an automated station produced
nearly a year of temperature measurements in 1988, although the wind record
is shorter because the anemometer was destroyed by high winds. The Agassiz
weather stations demonstrate that riming and icing can render some sensors
inoperable for extended period of time in the Canadian Arctic (B. Alt,
pers. comm.).
4. Workshop Recommendations
Workshop participants strongly recommended a program
of ice core drilling at high elevations in the Americas. The potential
regions for drilling projects differ widely in their geographic location,
elevation, and climate. To assess the value of the different sites, and
thereby evaluate their relative importance and feasibility, we identified
several key questions to be addressed:
The alternative concept of drilling several deep ice cores would require a more focused investment of resources to a smaller number of sites. In some locations such a strategy may be crucial, as there are places (especially in the inter-tropical zone) where the rate of climatic change at high elevation is so great that if cores are not recovered in the near future valuable portions of the records will be lost. Such sites would be the first to be drilled. Details regarding specific sites suggested within each region are outlined below. Specific issues and considerations are also indicated.
4.1 Antarctic Peninsula
There have been numerous cores recovered from the
peninsula, and several additional studies are planned for 1998 by the British
Antarctic Survey, and by the Instituto Antártico Argentino. A compilation
and analysis of all of the data should be undertaken, especially for the
recent past (e.g. since 1960), to aid in understanding the signals. There
was some discussion that a couple of east-west traverses should be undertaken
to acquire short cores, allowing a modern calibration. Despite numerous
AWSs, calibration of the signal in ice cores from the peninsula remains
a big issue. Strong support was voiced for the idea of compiling and analyzing
all of the existing AWS and meteorological station data into a database.
This work could be done as a joint project by students from South and North
America. There is also a need to develop techniques for year-round aerosol
sampling, to build upon the existing Brazilian program. The collection
of precipitation samples also needs improvement, to better understand the
climatic significance of isotopic variations.
4.2 Patagonian Icefields
Prior to the drilling of a deep ice core on one
of the icefields, additional investigations will be required. Information
on bedrock topography, accumulation rates, thermal regime, and climatic
gradients must be obtained to maximize the potential for obtaining a valuable
ice core record. Due to the difficulties of fieldwork and logistics in
the harsh climate of Patagonia (especially high wind and heavy precipitation,
rendering aircraft support difficult), lightweight, portable equipment
will be required for the geophysics and recovery of short cores. An additional
recommendation was made to develop and build a lightweight drill capable
of reaching depths of approximately 50 m, which will be necessary due to
the expected high accumulation rate on the icefields. At present, little
information exists on the firn/ice transition depth in the region. Also
recommended were AWSs, perhaps installed on nunataks to minimize complications
due to the high accumulation rate.
4.3 Patagonia to the Dry Axis
Specific recommendations were not made, pending
the reconnaissance of Tupungato in March. Nonetheless, some of the potential
sites in this region are easily accessible, which would reduce the logistical
expense of drilling. Ice masses in this section of the Andes are very important
to the water resources of the region (especially for agriculture), and
hence merit investigation in terms of their response to potential climate
change.
4.4 Tropics
Several possible sites in Ecuador emerged as high
priorities for drilling in the future. The glaciers of Antisana (5758 m
summit) are very important for water resources and hydroelectric power
generation, and a recently obtained 10 m core will provide information
about the suitability of the site. In addition, the Ecuadorian Atomic Energy
Commission operates a station near the mountain at Papajata, which would
be of great value in the calibration of the isotopic record. Cotopaxi would
be another target, to obtain a record before the mountain erupts again.
Prior to drilling the effect of heat flux from the mountain on the thermal
regime of the glaciers should be investigated. Establishing additional
AWSs at high elevations in Ecuador is also a high priority, to help assess
the scientific issues that could be addressed by ice cores from the volcanoes,
and permit calibration of any cores drilled; B. Francou of ORSTOM in collaboration
with INAMHI have begun work on this.
To the south in the Cordillera Real, Nevado Illimani
(6439 m) would provide the best possibility of a good record, because reconnaisance
short cores obtained from neighboring mountains by Francou (e.g. Mururata,
5868 m) indicate that signal quality improves with increasing elevation.
A record from Illimani would also be useful in comparison with that anticipated
from Nevado Sajama in 1997, as Illimani is directly upwind along the trajectory
of moisture-laden air mass advection from the Amazon Basin, to the east.
There is also a need to continue the existing monitoring
programs and mass balance studies on glaciers in this region, as fiscal
constraints seem to be reducing governmental interest and support (esp.
in Peru). Lastly, it would be helpful to assemble the isotope precipitation
data already collected, to further aid in the understanding isotopic signals
at low-latitudes.
4.5 North America (Canada and Alaska)
There were two sites identified as high priority
locations for deep ice core drilling: on the col between Prospector and
Russell Peaks (PR col) of the Mt. Logan massif, and on Mt. Oxford in northern
Ellesmere Island. A reconnaissance of the PR col site was conducted in
1988-89 by G. Holdsworth who reported that the col is an area of roughly
400 by 400 m. He measured a 10 m temperature of -29.5°C, and installed
an AWS which could not withstand the severe winds during the winter. Holdsworth
estimates that the accumulation rate is currently about one meter per year
(0.3 - 0.4 m w.e.). Radar data show that there is 200 m of firn and ice
on the col, with a strong possibility that a record could represent the
entire Holocene. The attraction to the Mt. Oxford site (2100 m) is that
the record probably contains less melt than the Agassiz Ice Core, due to
the slightly higher elevation and more northerly location. Additional sites
within the Queen Elizabeth Islands could be evaluated based on extensive
radar imagery flights over the area in 1995.
4.6 Other recommendations
There was strong sentiment expressed by participants
that collaboration resulting from the research should provide long-term
benefit to the people and labs in Latin America. Direct participation in
projects is desired, which could involve training in both field and analytical
techniques, as well as basic technology, the goal being to "reduce the
wide crevasse between north and south". Participants noted that while applied,
practical applications of our science are needed to get governmental attention,
there must also be support for basic research. This dilemma is illustrated
by the recent privatization of ElectroPeru, which jeopardizes a long-running
mass balance program in the country. Another specific idea was to have
SENHAMI become more involved in operating and maintaining the AWS in the
Cordillera Blanca.
The need for training of Latin American scientists
was a recurring theme, demonstrated by the fact that there are currently
no professionally trained glaciologists in Bolivia, and Chile has only
one, despite abundant glaciers and urgent water resource issues in both
countries. It was suggested that IAI funds could act as a seed to establish
or improve programs. This could be done through the direct involvement
suggested above, and also through the concept of offering ‘short courses’
at various South American institutions. These courses would offer hands-on
training by international teams of experts in different fields, who would
reside at the institutions for short periods and be available for discussions.
Realizing a program of research on climate variability
in the Americas from high elevation ice cores would serve many goals of
the IAI, because the program could be largely distributed in nature, and
involve many different institutions in aspects that range from highly technical
and specialized, to those which are more organizational in nature. Focused
aspects of individual ice core projects could greatly benefit the countries
involved by later transformation into studies with long-term monitoring
emphases, such as the weather stations and glacier mass balance studies.
All of this knowledge and information, along with these types of skills,
will be vitally important to the countries involved as water resources
become increasingly important. The knowledge gained about climate variability
through a transect along the Americas will benefit a much larger region,
as we attempt to better understand global climate change.
5. Acknowledgments
This workshop was supported by a Start-Up Grant
(Phase I) to the University of Massachusetts, from the Inter-American Institute
for Global Change Research (IAI). We would also like to thank Ms. Soledad
Luddeck and the staff of La Cascada for helping to make the meeting a success.
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