Elemental and isotopic composition of trapped gases in the Huascaran
and Sajama ice cores from South America.
Drilling ice cores on the summit of a strato volcano (Sajama) in SW
Bolivia in June 1997. Elevation = 6,500m
Elemental and isotopic composition of trapped gases in the Huascaran
and Sajama ice cores from South America
Active from 3/1/97-2/29/99
Funding agency: NSF Climate Dynamics
Project description: A set of very exciting climate records extending into
the last glacial period have recently been developed from the Huascar?n
ice core from the Peruvian Cordillera (9o6'S; 77o36'W, 6048 m above sea
level) [Thompson et al. , 1995] . The isotopic temperature record from
this core demonstrated that, during the last glacial period, temperatures
at Huascar?n were colder than today, supporting various lines of evidence
that the tropics were indeed colder during the last glacial period. In
addition, measurements of the chemical composition of the ice core suggest
higher dust concentrations in glacial ice from Huascar?n. These findings
are consistent with ice core records from Greenland and Antarctica which
extend into the last glacial period. The high degree of covariation between
all these records during the termination argues that there are strong teleconnections
between these sites which are probably responding to the same (or similar)
forcing functions. In this proposal, we propose to measure the elemental
and isotopic composition of the trapped gases in the Huascar?n ice core.
Specifically we propose to analyze the 18O/16O of O2 (d18Oatm) and the
[CH4] along the Huascar?n core. These records will hopefully provide definitive
evidence for the existence of glacial ice at Huascar?n. In addition, the
gas records will help refine the timescale for the Huascar?n core to within
500 years of that ascribed to the GISP II ice core from central Greenland.
The gas records will also allow us to transfer the Huascar?n climate records
into a "common temporal framework" where we can determine whether the climate
events recorded in the ice cores are local or global climate events In
addition, we expect to investigate the leads and lags between all these
climate records and many other records covering the last deglaciation.
The ultimate goal in this research is gain insight into the mechanisms
which caused the Earth to move out of the last glacial period by establishing
the sequence of events which led to the deglaciation. Placing the tropical
climate events from Huascar?n in this sequence will help decipher the nature
of the forcing mechanisms responsible for the last termination. As the
Huascar?n records provide a single point calibration of the tropics, it
is important to construct a similar set of records from another tropical
site extending into the last glacial period. We propose to do this by analyzing
the trapped gases in a suite of samples from the Sajama ice core (18oS;
69oW, 6548 m above sea level) which will be drilled in Bolivia by Lonnie
Thompson during the summer of 1997. Our goal is to obtain glacial stage
ice from Sajama and correlate the two ice cores through their gas records.
Comparisoin of the isotopic temperature records from the two sites should
reveal the broad geographic (tropical) temperature signal for comparison
with isotope temperature records from Greenland and Antarctica. Even if
glacial stage ice is not recovered from Sajama, our gas records will provide
dating control in the Holocene so we can compare the Sajama climate records
with Holocene records from around the globe.