Page 41 - Alternative Energy Systems in Building Design

18 GLOBAL WARMING: CLIMATIC AND ATMOSPHERIC CHANGES

who first theorized the correlation, further suggests that massive depopulation in the
New World during the 1500s was a result of the Americas being in contact with
Europe.

PRINCIPAL CAUSES OF THE LITTLE ICE AGE
At present, scientists have identified two probable causes for the little ice age: a
decrease or increase in volcanic eruptions. In essence, some researchers are of the
opinion that anthropogenic atmospheric pollution that affects climate is extremely
minor compared with natural events. As a matter of fact, some scientists consider
glaciations to be normal cycles for earth, as in the medieval warm period and the inter-
glacial glaciations period.

VOLCANIC ACTIVITY
Throughout the little ice age, the world also experienced severe volcanic eruptions,
which spewed enormous amounts of ash that reached high into the atmosphere and
covered the entire earth. In some instances, large amounts of volcanic ash can block
out incoming solar radiation, leading to worldwide cooling that can last up to several
years. Emitted volcanic ashes, in addition to large amounts of CO , contain significant
2
amounts of sulfur dioxide (SO ) gas. When the SO gas reaches the upper atmosphere,
2
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it combines with water particulates and turns into sulfuric acid, which amplifies the
reflection of the sun’s rays, further reducing the amount of radiation reaching earth’s
surface.
OCEAN CONVEYOR SHUTDOWN

Another possible cause of the little ice age is related to the disruption or slowing of
ocean conveyor, also known as the gulf stream. It could have been interrupted by the
introduction of large amounts of freshwater in the North Atlantic, possibly caused by
melting of glaciers during the medieval warming period. According to documented
records, around 1850 the global climate began warming, and the little ice age ended.
Notwithstanding, scientific opinion of the effects of the little ice age on climate change
is that warming over the last 50 years has increased proportions of CO in the atmosphere,
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stemming from human, or anthropogenic, activity.