Long before modern instrumentation, sunspots could be studied with no more equipment than a piece
of smoked glass, isinglass, or other animal membrane—and the ancient Chinese left written records.
Sunspots come and go, but they persist for long periods. (Galileo used them to time the rotation of the
sun.) Mean earth temperatures vary directly with the number of sunspots. In 1922, an English lady, An-
nie Maunder, correlated sunspot frequency with climatic records [150]. When sunspots almost disap-
peared, a period known as the Maunder Minimum, the Northern Hemisphere suffered the “Little Ice
Age.” From about 1500 to 1900 ADsunspots were few, with intermittent minima during one of which
England’s Thames River froze and another when George Washington’s army had the misfortune to be en-
camped at Valley Forge [151]. Evidence of the Little Ice Age, and also of the “Little Climatic Optimum”
500 years before, still lingers in deep rock temperatures [152].
Within the larger sunspot cycle is a minor, rather consistent, approximately 11 year, cycle. Curious
evidence of this is afforded by the trading records of Canada’s Hudson Bay fur company. Rythmic fluc-
tuations in the populations of prey animals, largely arctic hares and lemmings, are echoed 1 year later in
increases in pelts taken from carnivores, particularly the valuable white fox.
Geological evidence indicates wide variations in mean temperatures and CO 2 levels in past inter-
glacial [153] and even postglacial, Holocene [154] periods. Some have been correlated with volcanism or
meteor showers [155]. Archeology now indicates that collapse of some major Bronze Age civilizations
was due to droughts associated with volcanic eruptions [156]. When Mount Krakatoa blew up in 1883, it
lowered mean global temperature 0.27°C (0.5°F). The amounts of industrially released CO 2 are minor
compared with those from such natural forces.
Moreover, global warming is not necessarily harmful [157,158]. During the 11th century sunspot
maximum (the Little Climatic Optimum) Greenland supported a thriving farming community, as did the
Orkney Islands. During the Little Ice Age the Greenlanders died and the Orkney Islanders struggled to
survive. With today’s sunspot plenitude, the Orkneys have become Scotland’s major beef-producing
county [159], although green pastures have yet to return to Greenland.
Supposed scientific calculations and much popular alarmism predict that a few degrees of global
warming will cause disastrous flooding of many coastal areas and complete disappearance of low-lying
Pacific Islands due to melting of the polar icecaps [160]. History shows otherwise. During the 1000-
year cycle that included the Little Climatic Optimum and the Little Ice Age, sea levels did not change
materially [161]. Some ice-freed coasts rose, some coastlines eroded and others accreted, and occa-
sionally coastal subsidence became threatening. London is an example of the latter phenomenon. The
considerable engineering feat of the Thames Barrier has been necessitated by slight, but inexorable,
land subsidence and occasional coincidence of an abnormally high spring tide with a very strong north-
east wind.
Apparently minor temperature changes can have drastic effects due to their influence on the winds.
The El Niño phenomenon has had much publicity of late, although it is nothing new, as indicated by coral
growth records going back over 100,000 years [143,162] and by ocean and lake sediments [163] for
shorter periods. The apparent warming of hundreds of cubic miles of Pacific Ocean water is not due to
enormous amounts of added heat but to failure of the trade winds that normally push the sun-warmed wa-
ter toward the Philippines and Indonesia, without which they suffer devastating droughts.
Ground-penetrating radar shows that great mountain-fed rivers once transversed the Sahara Desert.
Cave paintings and rock carvings [164] prove that 8000 years ago the Sahara was verdant and teeming
with tropical wildlife. Such a scenario is now impossible with today’s wind patterns.
Obviously, any practices that are deleterious to the environment should be curtailed wherever it is
possible to do so without incurring unacceptable human and economic consequences. However, any cli-
matic effects from emissions of CO 2 from consumption of fossil fuels are trivial by comparison with na-
ture’s inexorable forces.
Conclusion: There is no foreseeable reason why producers of crops need to modify where or how
they grow them despite grossly exaggerated accounts of hazards from worldwide global warming.
V. CONCLUSION
With virtually any crop, from seed germination, bud sprouting, or anthesis to harvest, and after harvest to
final consumption, temperature plays important, and sometimes unsuspected, roles.
30 GRIERSON