Final Report Supplement - Joint Fire Science Program

Zotero Report zotero://report/items/520446_XG98FERT-520446_89BHQIMS-520446...
Type Journal Article
Author R. Matthew Beaty
Author Alan H. Taylor
Abstract This research examines how the controls of fire episode frequency in the northern Sierra Nevada have varied at
different temporal scales through the Holocene. A 5.5 m long sediment core was collected from Lily Pond, a
~2.5 ha lake in the General Creek Watershed on the west shore of Lake Tahoe in the northern Sierra Nevada in
California, USA. Dendrochronology was used to reconstruct the recent history of fire, and high-resolution
charcoal analysis was used to reconstruct fire episodes for the last 14 000 cal. yr BP. Fire episode frequency was
low during the Lateglacial period but increased through the middle Holocene to a maximum frequency around
6500 cal. yr BP. During the late Holocene fire episode frequency generally declined except for noted peaks
around 3000 cal. yr BP and 1000–800 cal. yr BP. These variations track major climatic and vegetation changes
driven by millennial-timescale variation in the seasonal cycle of insolation and regional decadal- and
centennial-scale variation in effective moisture in the mid and late Holocene in the Sierra Nevada. Fire episode
frequency during the Holocene in the Lake Tahoe Basin varied in response to decadal-, centennialand
millennial-scale climatic variability. Current fire episode frequency on the west shore of Lake Tahoe is at one of
its lowest points in at least the last 14 000 years. Given the strong relationship between climate and fire episode
frequency, warming due to increased levels of greenhouse gases in the atmosphere may increase fire episode
frequency to levels experienced during the ‘Mediaeval Warm Period’ or the early-Holocene summer insolation
maximum as periods of drought intensify.
Publication The Holocene
Volume 19
Issue 3
Pages 347–358
Date May 2009
Journal Abbr Holocene
DOI 10.1177/0959683608101386
ISSN 1477-0911
URL http://hol.sagepub.com/content/19/3/347.abstract
Extra Keywords: charcoal; climate change; Holocene; fire history; Sierra Nevada; California.
Date Added Tuesday, August 23, 2011 2:05:29 AM
Modified Wednesday, August 24, 2011 4:41:39 AM
A 2,300-year-long annually resolved record of the South American summer monsoon from the Peruvian
Andes
Type Journal Article
Author Broxton W. Bird
Author Mark B. Abbott
Author Mathias Vuille
Author Donald T. Rodbell
Author Nathan D. Stansell
Author Michael F. Rosenmeier
Abstract Decadal and centennial mean state changes in South American summer monsoon (SASM) precipitation during
the last 2,300 years are detailed using an annually resolved authigenic calcite record of precipitation δ¹⁸O from a
varved lake in the Central Peruvian Andes. This unique sediment record shows that δ¹⁸O peaked during the
Medieval Climate Anomaly (MCA) from A.D. 900 to 1100, providing evidence that the SASM weakened
considerably during this period. Minimum δ¹⁸O values occurred during the Little Ice Age (LIA) between A.D.
1400 and 1820, reflecting a prolonged intensification of the SASM that was regionally synchronous. After the
LIA, δ¹⁸O increased rapidly, particularly during the current warm period (CWP; A.D. 1900 to present),
indicating a return to reduced SASM precipitation that was more abrupt and sustained than the onset of the
MCA. Diminished SASM precipitation during the MCA and CWP tracks reconstructed Northern Hemisphere
and North Atlantic warming and a northward displacement of the Intertropical Convergence Zone (ITCZ) over
the Atlantic, and likely the Pacific. Intensified SASM precipitation during the LIA follows reconstructed
Northern Hemisphere and North Atlantic cooling, El Niño-like warming in the Pacific, and a southward
displacement of the ITCZ over both oceans. These results suggest that SASM mean state changes are sensitive
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