Geography Reference
In-Depth Information
•
Humid Subtropical:
warm to hot with dry winters
carbon from the vegetation is converted to CO
2
and re-
leased into the atmosphere. Soils, devoid of their biotic
cover, emit CO
2
at rates greater than ever before. Accord-
ing to the 2007 report of the International Panel on Cli-
mate Change (IPCC), the measure of
greenhouse gases
in the atmosphere has increased significantly . CO
2
levels
have risen 30 percent, methane gas (CH
4
) content has
more than doubled, and nitrous oxide (NO
2
) concentra-
tions have increased by at least 15 percent.
•
Tropical:
variable precipitation throughout the year
•
Tropical Monsoon:
wet summers and dry winters
T To understand this pattern, you can ask the follow-
ing questions. How near or far from the equator is a
place? Does it experience continental extremes or mod-
erating maritime influences? What is the elevation? Is
the place influenced by the presence of a topographic
barrier? Answering these questions will help you under-
stand regional similarities and differences in climate.
CARBON DIOXIDE
AND THE GREENHOUSE EFFECT
Greenhouse gases let short-wavelength radiation from
the sun pass through the atmosphere but they absorb
long-wave radiation emitted by the Earth' s surface,
thereby heating the atmosphere. Increase in greenhouse
gases is caused by such factors as:
Exponential growth of global population with
increasing consumption. Until recently , high
consumption rates have been assigned to industrial-
ized nations, mostly in the northern hemisphere.
Now , rapid consumption growth is taking place in
China (1.34 billion people) and India (1.2 billion).
If per capita commercial energy trends continue
unabated, the typical Chinese will out-consume
the typical American before 2040, with Indians
surpassing Americans by 2080.
Growing need for energy to support such activities
as heating and cooling homes, cooking food,
watching TV , and surfing the Internet.
Increasing use of automobiles and other machines
burning fossil fuels.
Global Warming
and Climate Change
We have all heard about
global warming
and
climate
change
as being perhaps
the
major issues of our time.
However, most of us have little understanding of what is
actually happening. In order to get a grasp on the
processes involved, we need to investigate both the
at-
mosphere
and the
greenhouse effect
.
THE ATMOSPHERE
All life on Earth depends on oxygen in the atmosphere.
Most of Earth' s atmosphere (90%) lies within 12.4 miles
(20 km) of the surface. The atmosphere provides thermal
insulation, which prevents extreme changes in tempera-
ture. Unequal heating of Earth' s atmosphere and surface
creates long-term climate and short-term weather pat-
terns. V ariations in heating and resultant pressure differ-
ences generate winds that help drive ocean currents. The
atmosphere also transfers large quantities of heat from
equatorial to polar latitudes.
The atmosphere is composed primarily of nitrogen
gas (N
2
) (78.08%) and oxygen (O
2
) (20.94%) by vol-
ume. A variety of other compounds, such as water vapor
(H
2
O), carbon dioxide (CO
2
) and ozone (O
2
) make up
the remaining .98 percent. While oxygen levels appear to
be stable at this time, CO
2
levels are not. The present
concentration of CO
2
in the atmosphere is higher than it
has been for at least 400,000 years! Since the amount of
CO
2
in the atmosphere is very small, its concentration
can be changed easily by the addition of more of it from
a number of sources.
Scientists have concluded that humans had altered
the makeup of the Earth' s atmosphere even before the
Industrial Revolution (1750) by clear-cutting forests in
Europe, China, and the Middle East. In the process,
Fossil fuel deposits, including coal, oil, and natural
gas, took tens of millions of years to form, but we are
burning them up at an unprecedented rate. Fossil fuel
consumption' is key by-product is CO
2
. Because of carbon
emissions, Earth atmosphere' s CO
2
levels will at least
double pre-1860 amounts by 2150 if present trends
continue.
The United States accounts for more than 20 percent
of carbon emissions from fossil fuel burning. While
emission rates continue to increase, the increments of in-
crease are lessening as we take action to improve the
environment.
Currently , however, the most significant increases in
carbon emissions are taking place in Asia. China' s emis-
sions rose by 9.1 percent in 2005 and now experts recog-
nize that it is emitting more CO
2
into the atmosphere
Search WWH ::
Custom Search