Evidence for Climate Teleconnections Between Greenland and the Sierra Nevada of California During the Holocene, Including the 8200 and 5200 Climate Events - Abrupt Climate Change: Mechanisms, Patterns, and Impacts - page 197

charcoal was deposited into Coburn Lake beginning 8120
years ago. This date corresponds closely with the 8150 date
given by Muscheler et al. [2004] for the 8200 year ACCE. As
described above, other evidence exists for the occurrence of
the 8200 year ACCE in North America [Alley and Agustsdot-
tir, 2005; Morrill and Jacobsen, 2005] and California [Moser
et al., 2004]. Benson et al. [1997] reported that Owens Lake,
located east of the southern Sierra Nevada, was wet from
10,000 to 8000 years ago. Meyer et al. [1995] reported a peak
in debris flows at approximately 8200 years ago in Yellow-

stone, Wyoming. Dean et al. [2006] found evidence for the
8200 year ACCE at Bear Lake, located in Utah and Idaho.
Potito et al. [2006] found that summer lake surface water
temperatures in the Sierra Nevada remained steady from ap-
proximately 11000 years ago until just before approximately
8000 years ago, at which point summer surface water tem-
peratures became abruptly colder. After this abrupt drop in
temperature, temperatures rose steeply, reaching their
Holocene maximum at approximately 6500 years ago.
Two smaller peaks of charcoal were deposited into Coburn
Lake at 7300 and 6500 years ago at the beginning of two of
the three severe droughts that occurred in the northern Sierra
Nevada following the 8200 year ACCE [Mensing et al.,
2004]. Three smaller charcoal peaks were deposited into
Coburn Lake at the beginning of all three of the severe
droughts that occurred between 6400 and 5200 years ago,
during a relatively wet period in the northern Sierra Nevada
[Mensing et al., 2004].
Mensing et al. [2004] reported that a severe drought
occurred in the northern Sierra Nevada from approximately
5200 to 5000 years ago. The beginning of this drought
corresponds closely with the timing of the 5200 year ACCE.
A large amount of charcoal was deposited into Coburn Lake
at the beginning of this drought, also synchronous with the
5200 year ACCE.
As described in section 1.1.2, evidence exists for the
occurrence of the 5200 year ACCE in locations as close as
British Columbia [Spooner et al., 1997] and the Great
Plains [Clark et al., 2002]. Meyer et al. [1995] reported a
peak in debris

Figure 4. Distribution of charcoal peaks from Coburn Lake (CL)
over the past 8500 years compared with the 7400 year long Pyramid
Lake (PL) drought record. (a) Drought record in the northern Sierra
Nevada [Mensing et al., 2004] with the addition of the of the 8200
year climate event from Coburn Lake. (b) Northern Sierra Nevada
drought record from Pyramid Lake, Nevada, based upon the ratio of
Artemisia (sagebrush) to Chenopodiaceae (shadscale) pollen types
(A/C) in Pyramid Lake sediments [Mensing et al., 2004]. S.U. is
standard units. (c) Number of charcoal particles of >250 μ m in size
per g 3 found within lake sediments. The two largest Coburn Lake
charcoal peaks (>1000 charcoal g 3 ) were truncated to tthe
column size. The dashed horizontal lines represent the centers of
major charcoal peaks.

flows in Yellowstone, Wyoming, at approxi-
mately 5000 years ago. Klem [2010] found evidence for a
glacial advance in the Uinta Mountains of Utah between
5300 and 5200 years ago. Barron et al. [2003] reported
evidence for increased ocean upwelling, warmer winters,
and increased fog off the coast of northern California at
5200 years ago.
In Greenland, the magnitude of variations in precipitation
decreased abruptly after the 5200 year ACCE (Figure 5).
Total precipitation in Greenland also began a general decline
after the 5200 year ACCE. Precipitation continued to decline
until approximately 3000 years ago.

severe droughts that occurred in the northern Sierra Nevada
over the past 7400 years [Mensing et al., 2004]. However,
little or no charcoal was deposited into Coburn Lake between
5000 and 3100 years ago (see below). Also, the Pyramid
Lake record is missing information for the time period be-
tween 3400 and 2750 years ago.
The Pyramid Lake record does not cover the climate record
as far back as 8200 years ago. However, a large amount of