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11.1.4.2 The Medieval Warm Period and the Little Ice Age
Evidence for the existence of the MWP and the LIA in the last 1,100 years has
been observed in various datasets. For example,
Figure 4.2
shows evidence of the
existence of the MWP and the LIA in the GISP2 ice core record. Idso (2008)
provides extensive evidence in favor of the existence of both.
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Grove (1988) pro-
vides 1,000 pages of evidence of the existence of the LIA. Moreover, there were
numerous temperature excursions comparable with or greater than current global
warming prior to the MWP.
Thorsteinsson showed evidence for the MWP and LIA in the Camp Century
ice core.
Dansgaard (2005) claimed that the MWP and the LIA ''were recognizable''
and ''stand out clearly'' in the Camp Century ice core. He also presented
Figure
Hole Oceanographic Institute website points out that both the LIA and MWP
show up in ice core records. So does Wally Broecker in his book The Glacial
World.
Shindell (2007) studied paleoclimatic data from a number of sources and
concluded:
''Historical data spanning the past millennium show substantial variations in
aridity in the dry bands of the subtropics
. Palaeoclimatic records from a
variety of sources and subtropical locations suggest that the MWP was generally
marked by drier conditions, including prolonged droughts, which became less
prevalent during the LIA. These records are supported by additional sediment
and lake level records, including some showing wetter conditions near the
equator, as well as fire residue and cultural records.''
...
Keigwin (1996) estimated sea surface temperatures in the Sargasso Sea over
the past few thousand years from isotope ratios of the remains of marine
organisms in sediments at the bottom of the sea (see
Figure 11.9
)
.
Esper et al. (2002) started out by repeating the mantra of the global-warming
alarmists:
the MBH reconstruction indicates that the 20th century warming is
abrupt and truly exceptional. It shows an almost linear temperature decrease
from the year 1000 to the late 19th century, followed by a dramatic and
unprecedented temperature increase to the present time. The magnitude of
warmth indicated in the MBH reconstruction for the MWP, 1000-1300 is
uniformly less than that for most of the 20th century.''
''
...
Esper et al. (2002) used data manipulation in much the same way as MBH,
but this led to a hockey stick that was somewhat different from that derived by
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Evidence in favor of the existence of the MWP and the LIA is collated at
http://
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