Environmental Engineering Reference
In-Depth Information
Warming spikes appeared more than 20 times in the Greenland ice
records. Within hundreds or thousands of years after the start of a warm
period, the climate went into slow cooling followed by quick cooling over
as short a time as a century. There would then begin another warming that
could take only a few years.
During the colder periods, icebergs floated as far south as Portugal.
One of these cold spells probably forced the Vikings out of Greenland.
This period is known as the Little Ice Age, which lasted from about 1400
to 1900.
Cold, wet times in Greenland occurred with very cold, dry, windy
conditions in Europe and North America along with very warm weather
in the South Atlantic and Antarctica. This weather is indicated by studies
of high mountain glaciers, the thickness of tree rings, and the types of
pollen and shells found in mud at the bottoms of lakes and oceans.
Cold periods in the north meant drought to Saharan Africa and India.
About 5,000 years ago a sudden drying spell changed the Sahara from a
green region spotted with lakes to a hot sandy desert.
In modern times, changing patterns in the North Pacific have been
strong enough to cause severe droughts, such as the one that triggered the
U.S. dust bowl of the 1930s. These warm spells, cold snaps or extended
droughts were caused by a gradual change in temperature or other
physical condition that pushed a critical driver of climate toward some
threshold.
UNDERGROUND CARBON
In Saskatchewan, deep underground, an experiment is underway to
determine if carbon dioxide can be safely buried. Carbon sequestration
could prove to be an effective way to reduce greenhouse gases.
The Weyburn oil field is 70 miles south of Regina and 50 miles north
of the U.S. border. It could hold over 20 million tons of carbon dioxide
over the project's expected 25-year lifespan. Saskatchewan's oil fields
are expected to have enough capacity to store all the province's carbon
dioxide emissions for more than three decades.
The Canadian government believes that carbon gas storage will help
the country meet its emissions reduction targets under the 1997 Kyoto
Protocol. It requires industrialized nations to cut emissions of greenhouse
gases by an average of 5% between 2008 and 2012.
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