SS3.09 Climate-Lake Interactions
Date: Wednesday, June 12, 2002
Time: 11:15:00 AM
Location: Colwood
 
MoserKA, University of Utah, Dept. of Geography, Salt Lake City, USA, katrina.moser@geog.utah.edu
Bloom, A, M, University of Utah, Dept. of Geography, Salt Lake City, USA, amy.bloom@geog.utah.edu
Porinchu, D, , Dept. of Geography, UCLA, Los Angeles, USA, porinchu@ucla.edu
MacDonald, G, M, Dept. of Geography and OBEE, UCLA, Los Angeles, USA, macdonal@geog.ucla.ed
Petel, A, , Dept. of Geography, UCLA, Los Angeles, USA, apost@ucla.edu
Potito, A, , Dept. of Geography, UCLA, Los Angeles, USA, potito@ucla.edu
 
INFERRING PAST CLIMATES OF THE SIERRA NEVADA,CALIFORNIA, USA, USING DIATOM- AND CHIRONOMID- INFERENCE MODELS
image
Here we present the first quantitative reconstructions of temporal climate variation in the Sierra Nevada, California, U.S.A., taking advantage of recent technological advances in lake sediment analysis. Steep climate gradients, related to elevation, make Sierra Nevadan lakes particularly sensitive to climate change. Multivariate statistical analyses of diatom, chironomid and environmental data from a 57-lake calibration set demonstrate that water temperature and salinity, proxies for air temperature and effective moisture, respectively, significantly influence diatom and chironomid distributions. Diatom- and chironomid-inference models for water temperature and salinity, developed from the calibration set, were applied to fossil diatom and chironomid assemblages from radiocarbon-dated lake sediment cores collected from the Sierra Nevada. Preliminary analyses, which focus on the late glacial and early Holocene transition, show that there are several rapid climate shifts that appear to correlate with events occurring in the North Atlantic and North Pacific, such as the Younger Dryas (YD) event. Our results indicate that in the Sierra Nevada the YD terminates with rapid warming (temperatures increase by at least 6 degrees C), decreased effective moisture and increased lake productivity.