Geoscience Reference
In-Depth Information
outright curtailment of emissions or through use of carbon
credits as a currency between countries. In other words, each
country would be allowed a certain number of carbon credits
that could be bought, sold, or traded.
Although the United States signed the treaty, it was re-
jected by the U.S Senate (where international treaties are rati-
fied) because it did not include guidelines for how developing
countries should adjust their greenhouse gas emissions. The
U.S. House of Representatives subsequently passed the
Ameri-
can Clean Energy and Security Act
in 2009, which sought
to establish a cap-and-trade system that limits the amount of
greenhouse emissions companies can produce. Like the Kyoto
Treaty, this latter piece of legislation failed to pass in the U.S.
Senate because opposing senators argued that the law would
hurt the national economy by forcing businesses and corpora-
tions to develop new technologies that would reduce carbon
emissions. Developing these technologies would add cost to
products made in the United States, which would theoretically
put us at a competitive disadvantage compared to developing
countries that have no carbon standards. The opposing view is
that climate change will add costs in the long run due to in-
creased occurrence of drought, fire, and sea level rise (to name
a few) that will far exceed the costs incurred now to mitigate the
process. Regardless, you can expect to hear about the climate
change issue for the rest of your life.
KEY CONCEPTS TO REMEMBER ABOUT
GLOBAL CLIMATE CHANGE
1.
A major issue facing the world today is global warming,
which most climatologists agree is related to human en-
hancement of the natural greenhouse effect.
2.
The carbon cycle refers to the way that carbon is stored
in various reservoirs (such as the atmosphere, ocean,
and rocks) and how it moves between them.
3.
In order to understand the extent of potential future cli-
mate change, it is necessary to understand prehistoric
climate variability. This can be reconstructed by indirect
methods, such as pollen analysis and dendrochronology.
4.
Since the onset of the Industrial Revolution in the mid-
1800s, atmospheric carbon dioxide has increased
about 30%. This increase is almost entirely due to hu-
man activities.
5.
Between the years
a
.
d
. 1000 and 1850, global climate
cooled slightly. Since 1850 it has been warming.
6.
General circulation models predict that average global
temperature will increase 2°C to 4°C (4°F-7°F) in this
century.
S u m m a r y o f K e y C o n C e p t S
1.
Climate refers to the average precipitation and tempera-
ture characteristics of a region. This depends on many in-
terrelated variables, including latitude, insolation, season-
ality, atmospheric circulation, and topographic effects.
tropical hot-summer climates (
Cfa
,
Cwa
), for example,
have hot summers and mild winters. The wet season oc-
curs in summer due to the influx of mT air pumped in by
offshore STH pressure systems.
2.
The Köppen climate system categorizes global cli-
mates based on their average annual temperature and
precipitation characteristics. Six major categories are
recognized: tropical humid climates (
A
), arid/semi-arid
climates (
B
), mesothermal climates (
C
), microthermal cli-
mates (
D
), polar climates (
E
), and highland climates (
H
).
6.
Microthermal (
D
) climates are largely continental cli-
mates that occur only in the Northern Hemisphere.
These climate regions have hot to mild summers and
cold winters. Average annual precipitation is moderate
and is usually associated with midlatitude cyclones.
7.
Polar (
E
) climates occur at very high latitudes and are
associated with tundra and ice caps. Although these re-
gions have a distinct annual temperature range, they are
generally cold with low to moderate precipitation. High-
land climates occur in mountainous areas and have the
characteristics of subarctic and polar climates.
3.
The humid tropical climates (
A
), such as the tropical rain-
forest climate (
Af
), have a low annual temperature range
and abundant precipitation caused by the Intertropical
Convergence Zone (ITCZ). Precipitation becomes dis-
tinctly seasonal with increased latitude in these regions.
4.
The arid/semi-arid climates (
B
) are regions of very low rainfall
and sparse vegetation. This low precipitation is caused by the
Subtropical High (STH) in places such as the Sahara Desert,
by the rain shadow effect in places like Denver, Colorado, and
by the continental effect in places like north-central China.
8.
The issue of climate change is highly visible on the current
national and international stage. In order to understand the
nature of future climate changes, it is important to understand
changes that have occurred in the recent geologic past.
9.
The Quaternary Period includes the most recent ~2 million
years of Earth's history. Several scientific methods, such as
palynology, dendrochronology, and oxygen isotope analy-
ses, can be used to reconstruct Quaternary climate changes.
5.
Mesothermal climates (
C
) are typically found in the mid-
latitudes. These climate regions have a distinct seasonal
temperature and precipitation pattern. The humid sub-
