Post-glacial climatic change and variability - The Global Climate System: Patterns, Processes, and Teleconnections - page 199

use of the term MWP. Certainly, there are places, particularly in northern
Europe, where the evidence is prevalent for warmer conditions in general
over that time frame. Nevertheless, as is shown for the LIA below,
Holocene climate is strongly characterized by the regionalization of climate
and it should not be surprising that conditions will be inconsistent from one
place to another at the same time. Moreover, a specific forcing component
can produce different responses in climate given the non-linearity of the
climate system.
Little Ice Age
The LIA was first used as a descriptive term referring to glacial activity over
the last 4000 years (now often referred to as Neoglaciation; Figure 6.2 ), the
formal term of LIA now often refers to the period from AD 1550 to 1850 (i.e.
mid sixteenth to mid nineteenth century) (Jones and Mann 2004 ). Many
records are available that support this contention, perhaps making the LIA
the most spatially coherent of the climatic regimes in the NH during the latest
parts of the Holocene. In fact, the most recent cool period of the cyclical
events in the Holocene is the LIA (Figures 6.3 - 6.5 ) . However, there still are
temporal and spatial differences from area to area in the NH, reflecting the
regionalization of Holocene climate, much like the evidence put forth to
question the existence of the MWP. As was the case for the MWP, part of
the variability in describing LIA climate is the different nature of various
proxy records including the spatial and temporal resolution of the data.
Records showing the variability in the LIA, as summarized by Jones et al.
( 1998 ) and Jones and Mann ( 2004 ), are now presented.
Greatest evidence for cooler climatic conditions in Europe covers the
period from the early to middle part of the nineteenth century (around
1820) to the earliest part of the twentieth century (around the 1920s).
Overall, the seventeenth century was also cold, but such conditions were
not as prevalent as those in the sixteenth and eighteenth centuries. Coldest
conditions in North America match those in Europe, as the nineteenth century
was the coldest of the last millennium. There is also evidence of a cold
seventeenth century, although places in the western United States may have
been warm during that century. Climatic conditions in eastern Asia may
deviate by the greatest amount from the general hemispheric climate, that
is, assuming that general LIA climate follows the conditions observed in
Europe and North America. For instance, there is little evidence for persis-
tently cold conditions in the nineteenth century in eastern Asia, but there is
evidence for cold climatic conditions in the seventeenth century. The late
eighteenth and earliest nineteenth centuries seemed to be cold in eastern Asia,
but these cold conditions do not appear to persist through the rest of that
century unlike conditions observed in Europe and North America.