Climate during the last glacial maximum in the Northern Sawatch range, Colorado, USA

Keith A. Brugger; Chester A. Ruleman; Marc W. Caffee; Cody C. Mason

doi:10.3390/quat2040036

Climate during the last glacial maximum in the Northern Sawatch range, Colorado, USA

Keith A. Brugger, Chester A. Ruleman, Marc W. Caffee, Cody C. Mason

Geology

Research output: Contribution to journal › Article › peer-review

14 Scopus citations

Abstract

Temperature-index modeling is used to determine the magnitude of temperature depression in the northern Sawatch Range required to maintain steady-state mass balances of six reconstructed glaciers at their extent during the local Last Glacial Maximum (LLGM), dated at ~21 ka. Assuming no significant differences in precipitation compared to modern values, mean annual temperatures in the region were on average 8.8 + 0.5/– 0.8^◦ C cooler than they are today. Allowing for modest (± 10 cm) increases or decreases in precipitation, required temperature depressions only differ by ±0.2^◦ C. Temperature depression in the northern Sawatch Range is consistent, although slightly greater, with those determined in other ranges in Colorado using similar approaches. The estimates presented here are, however, substantially less than those suggested by several downscaled simulations of global Last Glacial Maximum (LGM) climate, that might be due to the need for improved calibration of such downscaled simulations, or the models from which they are derived. Our estimates of LGM temperature depression are considerably greater than that previously determined in the study area and those in two other ranges in Colorado derived using different methodologies, the latter being most likely responsible for the discrepancies.

Original language	English (US)
Article number	36
Journal	Quaternary
Volume	2
Issue number	4
DOIs	https://doi.org/10.3390/quat2040036
State	Published - Dec 2019

Bibliographical note

Funding Information:
Funding: This work was supported by internal funds within the U.S.G.S., PRIME Lab, and the University of Minnesota, Morris.

Funding Information:
Acknowledgments: Geologic mapping and sample collection and processing was supported and made available through the U.S. Geological Survey National Geologic Mapping Cooperative Program. A. Hudson and four anonymous reviewers provided helpful comments to improve the original manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Funding Information:
This work was supported by internal funds within the U.S.G.S., PRIME Lab, and the University of Minnesota, Morris. Geologic mapping and sample collection and processing was supported and made available through the U.S. Geological Survey National Geologic Mapping Cooperative Program. A. Hudson and four anonymous reviewers provided helpful comments to improve the original manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Publisher Copyright:
© 2019 by the authors. Licensee MDPI, Basel, Switzerland.

Keywords

Colorado
Last Glacial Maximum
Paleoclimate
Sawatch Range
Temperature-index model

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10.3390/quat2040036

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title = "Climate during the last glacial maximum in the Northern Sawatch range, Colorado, USA",

abstract = "Temperature-index modeling is used to determine the magnitude of temperature depression in the northern Sawatch Range required to maintain steady-state mass balances of six reconstructed glaciers at their extent during the local Last Glacial Maximum (LLGM), dated at ~21 ka. Assuming no significant differences in precipitation compared to modern values, mean annual temperatures in the region were on average 8.8 + 0.5/– 0.8◦ C cooler than they are today. Allowing for modest (± 10 cm) increases or decreases in precipitation, required temperature depressions only differ by ±0.2◦ C. Temperature depression in the northern Sawatch Range is consistent, although slightly greater, with those determined in other ranges in Colorado using similar approaches. The estimates presented here are, however, substantially less than those suggested by several downscaled simulations of global Last Glacial Maximum (LGM) climate, that might be due to the need for improved calibration of such downscaled simulations, or the models from which they are derived. Our estimates of LGM temperature depression are considerably greater than that previously determined in the study area and those in two other ranges in Colorado derived using different methodologies, the latter being most likely responsible for the discrepancies.",

keywords = "Colorado, Last Glacial Maximum, Paleoclimate, Sawatch Range, Temperature-index model",

author = "Brugger, {Keith A.} and Ruleman, {Chester A.} and Caffee, {Marc W.} and Mason, {Cody C.}",

note = "Funding Information: Funding: This work was supported by internal funds within the U.S.G.S., PRIME Lab, and the University of Minnesota, Morris. Funding Information: Acknowledgments: Geologic mapping and sample collection and processing was supported and made available through the U.S. Geological Survey National Geologic Mapping Cooperative Program. A. Hudson and four anonymous reviewers provided helpful comments to improve the original manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Funding Information: This work was supported by internal funds within the U.S.G.S., PRIME Lab, and the University of Minnesota, Morris. Geologic mapping and sample collection and processing was supported and made available through the U.S. Geological Survey National Geologic Mapping Cooperative Program. A. Hudson and four anonymous reviewers provided helpful comments to improve the original manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Publisher Copyright: {\textcopyright} 2019 by the authors. Licensee MDPI, Basel, Switzerland.",

year = "2019",

month = dec,

doi = "10.3390/quat2040036",

language = "English (US)",

volume = "2",

journal = "Quaternary",

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T1 - Climate during the last glacial maximum in the Northern Sawatch range, Colorado, USA

AU - Brugger, Keith A.

AU - Ruleman, Chester A.

AU - Caffee, Marc W.

AU - Mason, Cody C.

N1 - Funding Information: Funding: This work was supported by internal funds within the U.S.G.S., PRIME Lab, and the University of Minnesota, Morris. Funding Information: Acknowledgments: Geologic mapping and sample collection and processing was supported and made available through the U.S. Geological Survey National Geologic Mapping Cooperative Program. A. Hudson and four anonymous reviewers provided helpful comments to improve the original manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Funding Information: This work was supported by internal funds within the U.S.G.S., PRIME Lab, and the University of Minnesota, Morris. Geologic mapping and sample collection and processing was supported and made available through the U.S. Geological Survey National Geologic Mapping Cooperative Program. A. Hudson and four anonymous reviewers provided helpful comments to improve the original manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Publisher Copyright: © 2019 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2019/12

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N2 - Temperature-index modeling is used to determine the magnitude of temperature depression in the northern Sawatch Range required to maintain steady-state mass balances of six reconstructed glaciers at their extent during the local Last Glacial Maximum (LLGM), dated at ~21 ka. Assuming no significant differences in precipitation compared to modern values, mean annual temperatures in the region were on average 8.8 + 0.5/– 0.8◦ C cooler than they are today. Allowing for modest (± 10 cm) increases or decreases in precipitation, required temperature depressions only differ by ±0.2◦ C. Temperature depression in the northern Sawatch Range is consistent, although slightly greater, with those determined in other ranges in Colorado using similar approaches. The estimates presented here are, however, substantially less than those suggested by several downscaled simulations of global Last Glacial Maximum (LGM) climate, that might be due to the need for improved calibration of such downscaled simulations, or the models from which they are derived. Our estimates of LGM temperature depression are considerably greater than that previously determined in the study area and those in two other ranges in Colorado derived using different methodologies, the latter being most likely responsible for the discrepancies.

AB - Temperature-index modeling is used to determine the magnitude of temperature depression in the northern Sawatch Range required to maintain steady-state mass balances of six reconstructed glaciers at their extent during the local Last Glacial Maximum (LLGM), dated at ~21 ka. Assuming no significant differences in precipitation compared to modern values, mean annual temperatures in the region were on average 8.8 + 0.5/– 0.8◦ C cooler than they are today. Allowing for modest (± 10 cm) increases or decreases in precipitation, required temperature depressions only differ by ±0.2◦ C. Temperature depression in the northern Sawatch Range is consistent, although slightly greater, with those determined in other ranges in Colorado using similar approaches. The estimates presented here are, however, substantially less than those suggested by several downscaled simulations of global Last Glacial Maximum (LGM) climate, that might be due to the need for improved calibration of such downscaled simulations, or the models from which they are derived. Our estimates of LGM temperature depression are considerably greater than that previously determined in the study area and those in two other ranges in Colorado derived using different methodologies, the latter being most likely responsible for the discrepancies.

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KW - Last Glacial Maximum

KW - Paleoclimate

KW - Sawatch Range

KW - Temperature-index model

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ER -

Climate during the last glacial maximum in the Northern Sawatch range, Colorado, USA

Abstract

Bibliographical note

Keywords

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