Meteorology 211
Spring Quarter 2011
Homework Assignment #3
Due Date: Friday, May 13
Answer
the following questions based on the assigned reading and classroom
discussions. Answers must be typed. Please use complete sentences.
1) a. What was the “Paleocene-Eocene Thermal Maximum” and when did it
occur?
(a)
The Paleocene-Eocene Thermal Maximum was an event that occurred during
the Paleocene epoch, 55 million years ago, when an enormous mass of
carbon flooded the ocean and atmosphere. (In less than 1000years
1500-4500 gigatons of carbon entered the climate system raising the
surface temperature 5 to 9 degrees Celsius and the ocean acidified.
b. Why is this past event potentially important in understanding what may
be happening in our current changing climate?
(b)
The past event is potentially important in understanding what may be
happening in our current changing climate because it is analogous of the
current situation….1500-4500 gigatons of carbon that entered the
climate system in the Paleocene epoch is about the same amount of carbon
projected to enter it as a consequence of human activities during the
twenty-first century if fossil-fuel use continues to grow at the current
pace.
2) Why is it misleading to refer to the “Ice Age” as a singular past event?
The term ice age is
somewhat misleading because it does not mean that the planet has been
completely and perennially frozen. Rather, during this time the climate
has fluctuated rapidly between glacial intervals lasting tens of
thousands of years and shorter interglacial intervals. (Mathez,
2009(Pg102))
3) Describe the three main characteristics of Earth orbital cycles called “Milankovitch Cycles”.
Earth’s
orbital parameters of precession (Earth's axis of spin relative to the
orbital axis once about every 21,000 years), obliquity(the tilt of the
axis of rotation relative to the solar plane….currently 23.5 degrees,
changes from 21.5 and 24.5 degrees and back again approximately every
41,000years.), and eccentricity(the degree that Earth's orbit around the
sun departs from a circle) as well as the way their individual,
cyclical effects combine to influence summer insolation at 65°N
latitude. These combined effects of the orbital parameters on insolation
are known as Milankovitch cycles.
4) Examine Figure 6.5 on page 110 of the textbook.
a. From what source(s) of data are the two plots on this figure based?
(a)The
two plots are based on analyses of air trapped in Antarctic ice cores
compared with the temperature record derived from the composition of
ice.
b. Using just an “eyeball analysis” to compare the two curves, what would
your conclusion be regarding the relationship between atmospheric
CO2 concentration and temperature over the last 800,000 years?
(b)My
conclusion regarding the relationship between atmospheric CO2
concentration and temperature over the last 800,000 years is that they
are very similar.
5) Why can’t carbon-14 dating be used to date the age of rocks?
Carbon-14
dating is dependent upon the presence of Carbon-14 that organisms
ingest directly from the atmosphere. Some problems with using carbon-14
dating on rock of whatever kind:
It
was never alive, It never ingested atmospheric carbon-14, It didn't
cease to ingest further carbon-14 when it died, seeing as it never died,
and Most rock is older than 50,000 years. While rock samples may
contain carbon-14, it didn't come directly from the atmosphere.
6)
Look at Figure 7.1 on page 133 in the textbook, and focus in on the
period 1940 to about 1975. Describe the trend in global surface air
temperature during this period, and explain the prevailing hypothesis on
why this occurred.
The
intervening interval, from 1940-1979 was characterized by a stable
temperature or even slight cooling, possibly due to atmospheric aerosols
from human activities. (Mathez, 2009 (Pg132))
7)
Would you be willing to say that Hurricane Katrina in 2005 is direct
evidence that global warming is occurring? Why or why not?
I
don't think that Hurricane Katrina in 2005 is direct evidence that
global warming is occurring because hurricanes have always
happened….however the magnitude of Katrina may have been influence by
climate changes caused by human activities.
8)
Over the period 1975-2005, how did the change in average surface air
temperature in the Arctic compare to that observed over the Earth as a
whole?
From
1975-2005, Artic surface temperature increased about 0.7 degrees
Celsius per decade, which is more than double the 0.3 degrees pre decade
rise in global surface temperature.
9) a. What is the definition of permafrost?
(a) The term permafrost refers to soil or rock that has been below 0°C (32°F) and frozen for at least two years.
b. Explain how melting Arctic permafrost can act as a positive feedback
mechanism in global warming.
(b)
There is also the important albedo feedback between melting and
temperature. Ice is more reflective than water, so as the proportion of
open water increases and that of ice decreases, more energy is absorbed
by the ocean. Heat thus builds up both in the ocean and in the
atmosphere and accelerates the melting.
(Mathez, 2009)
10)
About how much has average sea level risen during the past 21,000 years
(the peak of the last glacial maximum)? Was this change entirely due to
melting of the large continental ice sheets, or was there another
effect on sea level related to climate warming?
About
21,000 years ago, at the most recent glacial maximum, the sea level
stood approximately 120 meters (400 feet) below its present level. With
the subsequent melting of the Northern Hemisphere ice cap, sea level
rose quickly, but then, according to geological evidence, the rising
slowed so that over the past 3,000 years sea level rose about 1 to 2
centimeters (0.4 to 0.8 inch) per century before the twentieth century.
Tide gauge data, however, put the twentieth-century rise at a more
rapid and accelerating 15 to 20 centimeters (6 to 8 inches), apparently
from increased glacial discharge.
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