Present climate and biological change - Climate Change: Biological and Human Aspects - page 214

the severity of the Little Ice Age outside of the northern hemisphere is not so clear,
although there is evidence of other climatic change, other than temperature, such
as changes in aridity/precipitation. Similarly, in the Kuiseb River Delta of Nambia
settlements were abandoned between 1460 and 1640 (Tyson et al., 2002). Was this
due to the Little Ice Age? There is oxygen isotopic evidence from stalagmites in
Makapansgat that the termination of what are assumed to be Little Ice Age effects
in South Africa was abrupt. Also, as discussed in the last chapter, irrespective of its
extent, even in the northern hemisphere the reasons for the Little Ice Age are not
entirely clear. This should alert policy-makers considering future climate change that
distinctive climatic-forcing events are not necessary for climate change associated
with considerable human impact: combinations of lesser forcing factors may result
in marked human impact.
In Western Europe during the Little Ice Age there was a general cooling of the
climate between 1150 and 1460 and a very cold climate between 1560 and 1850
that had dire consequences for its people. The colder weather impacted agriculture,
health, economics, social strife, emigration and even art and literature. Increased
glaciation and storms also had a devastating effect on those who lived near glaciers
and the sea. In the northern hemisphere the more severe climatic changes were not
restricted to Europe, however. In China the population fell from around 100 million
in the mid-13th century by about 40% over the next century or so.
What happened in terms of human impact has been pieced together from a variety
of sources. Records of English, French and German harvests and/or prices survive
to this day and these correlate well with the weather in good and bad years. So, it is
easy to see that each of the peaks in prices corresponds to a particularly poor harvest,
mostly due to unfavourable climates, with the most notable price peak in the year
1816 - 'the year without a summer' - following the Tambora eruption of 1815 (see
Figure 2.1).
The Little Ice Age harvest losses not only caused price increases but death too.
Famines became more frequent and in 1315 one killed an estimated 1.5 million in
Europe. This was probably the first big famine of the Little Ice Age and may have
been aggravated because agricultural systems were still partly embedded in MCA
mode that lasted through much of the 13th century. This happened elsewhere in the
northern hemisphere. In the east, as mentioned, there was famine in China. In the
west of the northern hemisphere, at the century's end the Anasazi abandoned their
long-established communities in the now desert of the south-western USA. At the
time, North American climatic belts shifted, including those suitable for economically
important crops: in what is now Wisconsin the northern limit of maize cultivation
moved southwards by up to 320 km.
At the beginning of the 14th century Northern Europe saw two exceptionally
severe winters, in 1303 and 1306. However, it was the run of cool and wet summers
between 1314 and 1317 that particularly decimated harvests, hence precipitating the
aforementioned great famine of 1315. Records show that this reduced the food supply
from Scotland to the Pyrenees and as far east as Russia. In some places, even when
plant growth was good, the wet, as is clearly recorded in England, made the harvest
difficult. In London in the spring of 1316 the price of wheat rose 8-fold over that of
late 1313: these price levels were not to be reached again until later in the Little Ice