36127 Topic: SCI 207 Our Dependence upon the Environment
Number of Pages: 1 (Double Spaced)
Number of sources: 2
Writing Style: APA
Type of document: Essay
Academic Level:Undergraduate
NCategory: Environmental Issues
Language Style: English (U.S.)
Order Instructions: Attached
Week 4 – Assignment 1
Greenhouse Gases and Sea Level Rise Laboratory
[WLO: 3] [CLOs: 1, 3, 5]
This lab enables you to create models of sea level rise resulting from melting of sea ice and glacier ice and examine the effects of this potential consequence of climate change.
The Process:
Take the required photos and complete all parts of the assignment (calculations, data tables, etc.). On the “Lab Worksheet,” answer all of the questions in the “Lab Questions” section. Finally, transfer all of your answers and visual elements from the “Lab Worksheet” into the “Lab Report.” You will submit both the “Lab Report” and the “Lab Worksheet” through Waypoint.
The Assignment:
Make sure to complete all of the following items before submission:
Read the Greenhouse Gases and Sea Level Rise Investigation ManualPreview the document and review The Scientific Method (Links to an external site.)Links to an external site.presentation video.
Complete Activities 1 and 2 using materials in your kit, augmented by additional materials that you will supply. Photograph each activity following these instructions:
When taking lab photos, you need to include in each image a strip of paper with your name and the date clearly written on it.
Activity 2, Step 12 will require you to make a line graph. Should you desire further guidance on how to construct a graph, it is recommended that you review the Introduction to GraphingPreview the document lab manual. (You are not expected to complete any of the activities in this manual.)
Complete all parts of the Week 4 Lab WorksheetPreview the document and answer all of the questions in the “Lab Questions” section.
Transfer your responses to the lab questions and data tables and your photos from the “Lab Worksheet” into the “Lab Report” by downloading the Lab Report TemplatePreview the document.
Submit your completed “Lab Report” and “Lab Worksheet” through Waypoint.
Carefully review the Grading Rubric (Links to an external site.)Links to an external site. for the criteria that will be used to evaluate your assignment.
ENVIRONMENTAL SCIENCE
GREENHOUSE GASES AND SEA LEVEL RISE
Overview
In this lab, students will carry out several activities aimed at
demonstrating consequences of anthropogenic carbon emissions,
climate change, and sea level rise. To do this, students will first
create a landform model based on a contour map. They will create
models of sea level rise resulting from melting of sea ice and
glacier ice and examine the effects of this potential consequence
of climate change. Students will critically examine the model
systems they used in the experiments.
Outcomes
• Explain the causes of increased carbon emissions and their likely
effect on global climate.
• Discuss positive and negative climate feedback.
• Distinguish between glacial ice melt and oceanic ice melt.
• Construct a three-dimensional model from a two-dimensional
contour map.
• Evaluate and improve a model system.
Time Requirements
Preparation:
Part 1……………………………………………………………….. 5 minutes,
then let sit for 24 hours before starting Activity 1
Part 2 ……………………………………………………………………2 hours
Activity 1: Sea Ice and Sea Level Rise ……………………………..1 hour
Activity 2: Glacier Ice and Sea Level Rise…………………….2.5 hours
2 Carolina Distance Learning
Key
Personal protective
equipment
(PPE)
goggles gloves apron
follow
link to
video
photograph
results and
submit
stopwatch
required
warning corrosion flammable toxic environment health hazard
Made ADA compliant by
NetCentric Technologies using
the CommonLook® software
Table of Contents
2 Overview
2 Outcomes
2 Time Requirements
3 Background
10 Materials
10 Safety
11 Preparation
13 Activity 1
14 Activity 2
15 Submission
15 Disposal and Cleanup
16 Lab Worksheet
18 Lab Questions
Background
For the last 30 years, controversy has
surrounded the ideas of global warming/climate
change. However, the scientific concepts behind
the theory are not new. In the 1820s, Joseph
Fourier was the first to recognize that, given
the earth’s size and distance from the sun,
the planet’s surface temperature should be
considerably cooler than it was. He proposed
several mechanisms to explain why the earth
was warmer than his calculations predicted,
one of which was that the earth’s atmosphere
might act as an insulator. Forty years later,
John Tyndall demonstrated that different
gases have different capacities to absorb
infrared radiation, most notably methane (CH4
),
carbon dioxide (CO2
), and water vapor (H2
O),
all of which are present in the atmosphere. In
1896, Svante Arrhenius developed the first
mathematical model of the effect of increased
CO2
levels on temperature. His model predicted
that a doubling of the amount of CO2
in the
atmosphere would produce a 5–6 °C increase
in temperature globally. Based on the level of
CO2
production in the late 19th century, he
predicted that this change would take place
over thousands of years, if at all. Arrhenius used
Arvid Högbom’s calculations of industrial CO2
emissions in his equations. Högbom thought
that the excess CO2
would be absorbed by the
ocean; others believed that the effect of CO2
was insignificant next to the much larger effect
of water vapor.
It was not until the late 1950s, when the CO2
absorption capacity of the ocean was better
understood and significant increases in CO2
levels (a 10% increase from the 1850s to the
1950s) were being observed by G. S. Callendar,
that Arrhenius’s calculations received renewed
attention.
The Atmosphere
Weather is the condition of the atmosphere in a
given location at a specific time. Climate is the
prevailing weather pattern over a longer period
of time (decades or centuries).
The atmosphere is a thin shell (~100 km) of
gases that envelops the earth. It is made up
principally of nitrogen (78%), oxygen (21%),
and argon (0.9%). Trace gases include methane
(CH4
), ozone (O3
), carbon dioxide (CO2
), carbon
monoxide (CO), and oxides of nitrogen (e.g.,
NO2
) and sulfur (e.g., SO2
) (see Figure 1).
Water vapor is sometimes included in the
composition of gases in the atmosphere, but a
lot of times it is not because its amount varies
widely, from 0%–4%, depending on location.
The concentration of gases in the atmosphere
is not uniform either; the atmosphere consists
of several concentric layers. Some gases are
concentrated at certain altitudes. Water and
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GREENHOUSE GASES AND SEA LEVEL RISE
Background continued
carbon dioxide are concentrated near the
earth’s surface, for instance, while ozone is
concentrated 20 to 30 kilometers above the
surface. Energy transfer from the sun at and
near the surface of the earth is responsible for
weather and climate. Solar radiation heats land,
the oceans, and atmospheric gases differently,
resulting in the constant transfer of energy
across the globe.
Several factors interact to cause areas of the
earth’s surface and atmosphere to heat at
different rates, a process called differential
heating. The first is the angle at which the sun’s
light hits the earth. When the sun is directly
overhead, as it is at the equator, the light is
direct. Each square mile of incoming sunlight
hits one square mile of the earth. At higher
latitudes, the sun hits at an angle, spreading
the one square mile of sunlight over more of the
earth’s surface. Thus, the intensity of the light
is reduced and the surface does not warm as
quickly (see Figure 2). This causes the tropics,
near the equator, to be warmer and the poles to
be cooler.
Different materials heat and cool at different
rates. Darker surfaces heat faster than lighter
surfaces. Water has a high heat capacity, which
is important on a planet whose surface is 72%
water. Heat capacity is a measure of how
much heat it takes to raise the temperature of
a substance by one degree. The heat capacity
of liquid water is roughly four times that of air.
Water is slow to warm and slow to cool, relative
to land. This also contributes to differential
heating of the earth.
Differential heating causes circulation in the
atmosphere and in the oceans. Warmer fluids
are less dense and rise, leaving behind an area
of low pressure. Air and water move laterally to
distribute the change in pressure. This is critical
in developing prevailing wind patterns and in
cycling nutrients through the ocean.
The Role of the Oceans
The oceans play an important role in regulating
the atmosphere as well. The large volume of the
oceans, combined with the high heat capacity
of water, prevent dramatic temperature swings
in the atmosphere. The relatively large surface
area of the oceans, ~70% of the surface of the
earth, means that the oceans can absorb large
amounts of atmospheric CO2
.
Greenhouse Gases
The greenhouse effect is a natural process;
continued on next page
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Figure 2.
without it, the earth would be significantly cooler
(see Figure 3). The sun emits energy in a broad
range of wavelengths. Most energy from the
sun passes through the atmosphere. Some is
reflected by the atmosphere and some by the
earth’s surface back into space, but much of it
is absorbed by the atmosphere and the earth’s
surface. Absorbed energy is converted into
infrared energy, or heat. Oxygen and nitrogen
allow incoming sunlight and outgoing thermal
infrared energy to pass through. Water vapor,
CO2
, methane, and some trace gases absorb
infrared energy; these are the greenhouse
gases. After absorbing energy, the greenhouse
gases radiate it in all directions, causing the
temperature of the atmosphere and the earth
to rise.
Greenhouse gases that contribute to the
insulation of the earth can be grouped into
two categories: condensable and persistent.
Persistent gases—such as CO2
, methane,
nitrous oxide (N2
O), and ozone (O3
)—exist in
the environment for much longer periods of
time than condensable gases. These times can
range from a few years to thousands of years.
The longer residence allows them to become
well-mixed geographically. The amount of a
condensable gas is temperature dependent.
Water is the primary greenhouse gas in the
atmosphere, but because it is condensable,
it is not considered a forcing factor. Forcing
factors (forcings) are features of the earth’s
climate system that drive climate change; they
may be internal or external to the planet and its
atmosphere. Feedbacks are events that take
place as a result of forcings.
Carbon dioxide, methane, and other gases
identified by Tyndall as having high heat
capacities make up a relatively minor fraction
of the atmosphere, but they have a critical
effect on the temperature of the earth. Without
the naturally occurring greenhouse effect, it is
estimated that the earth’s average temperature
would be approximately –18 °C (0 °F). The
greenhouse effect also acts as a buffer, slowing
both the warming during the day and the cooling
at night. This is an important feature of the
earth’s atmosphere. Without the greenhouse
effect, the temperature would drop below
the freezing point of water and the amount
of water in the atmosphere would plummet,
creating a feedback loop. A feedback loop is
a mechanism that either enhances (positive
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Figure 3.
GREENHOUSE GASES AND SEA LEVEL RISE
Background continued
feedback) or dampens (negative feedback) the
effect that triggers it.
Since the beginning of the Industrial Revolution,
the concentration of CO2
in the atmosphere
has increased from approximately 280 ppm
to 411 ppm (see the Keeling Curve link). This
change is attributed to the burning of fossil
fuels—such as coal, oil, and natural gas—and
changes in land use, i.e., cutting down large
tracts of old-growth forests. Old-growth forests,
like fossil fuels, sequester carbon from the
atmosphere. Burning of either releases that
carbon into the atmosphere in the form of CO2
.
Clearing old-growth forests has an additional
impact on the carbon cycle because trees
actively remove CO2
from the atmosphere to
convert it to sugar and carbohydrates (see
Figure 4). Removing long-lived trees and
replacing them with short-lived crops and
grasses reduces the time over which the carbon
is removed from the atmosphere.
Determining the exact effect that the increase
in CO2
concentrations will have on atmospheric
temperature is complicated by a variety of
interactions and potential feedback loops.
However, the overall impact is an ongoing
temperature increase, known as global climate
change (see Figure 5).
Potential Feedback Loops
Some examples of potential positive feedback
loops that may enhance the effects of global
climate change are:
1. Higher temperatures allow the
atmosphere to absorb more
water. More water vapor in the
atmosphere traps more heat,
further increasing temperature.
2. Melting of sea ice and glaciers,
which are relatively light in
color, to darker bodies or water
decreases the albedo (the
amount of energy reflected
back into space) of the
earth’s surface, increasing
temperatures. Figure 6 shows an
ice albedo feedback loop.
3. Warmer temperatures melt more
of the arctic permafrost (frozen
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Figure 4.
ground), releasing methane into the
atmosphere, further raising temperatures.
4. Higher temperatures may result in greater
rainfall in the North Atlantic, and melting of
sea ice creates a warm surface layer of fresh
