HW#1_EarthENERGYBUDGET
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Simon Fraser University *
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Course
110
Subject
Geography
Date
Apr 3, 2024
Type
docx
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6
Uploaded by LieutenantExploration13521
Daniela Jiménez (00322800)
Climate Change - CRN 3586
September 1
st
, 2023
Global Climate Change: Economics, Science, and Society
Homework #1
1.
Use the numbers given in the annual global energy budget to answer the following questions. a.
In one column, rank from largest to smallest, the radiative sources of heating for the atmosphere. In a second column do the same for the radiative sources of cooling for the atmosphere. Sum the sources of both the heating and cooling. Based on the totals, if there were no other sources of heating and cooling, would the temperature of the atmosphere rise or fall? (2.5 pts)
Radiative sources of heating for the atmosphere
1.
Surface radiation
2.
Solar radiation absorbed by the atmosphere
Radiative sources of cooling for the atmosphere
1.
Back radiation absorbed by surface
2.
Outgoing longwave radiation
1
Sum of the radiative sources of heating:
390
W m
−
2
+
67
W m
−
2
=
457
W m
−
2
Sum of the radiative sources of cooling:
324
W m
−
2
+
235
W m
−
2
=
559
W m
−
2
Sum of heating and cooling radiative sources:
457
W m
−
2
−
559
W m
−
2
=−
102
W m
−
2
Answer:
As the radiative sources of cooling leave the atmosphere, their values are negative. Therefore, if the result that was obtained from the total sum of both heating and cooling sources has a negative value, this means that the temperature of the atmosphere would fall
(if there were no other sources of heating and cooling besides the
ones shown in the picture).
b.
Do the same for the surface. If the only sources of heating and cooling for the surface were radiative, would the temperature of the surface rise or fall? (2.5 pts)
Radiative sources of heating for the surface
1.
Back radiation absorbed by surface
2.
Solar radiation absorbed by surface
Radiative sources of cooling for the surface
1.
Surface radiation
Sum of the radiative sources of heating:
324
W m
−
2
+
168
W m
−
2
=
4 92
W m
−
2
Sum of the radiative sources of cooling:
390
W m
−
2
Sum of heating and cooling radiative sources:
4 92
W m
−
2
−
390
W m
−
2
=
102
W m
−
2
Answer:
As the radiative sources of cooling leave the surface, their values are negative. Therefore, if the result that was obtained from the total sum of both heating and cooling sources has a positive value, this means that the temperature of the surface would rise
(if there were no other sources of heating and cooling besides the ones shown in the picture).
2
c.
What heating/cooling sources make up the deficits for 1) the atmosphere and 2) the surface? (1.5 pts)
To find out what sources make up the deficit (
heating sources =
cooling sources
), we first
look at the values of the heating/cooling sources from the previous task. Then, we determine the values that are needed to equalize all heating and cooling sources for the atmosphere and the surface. 1) Atmosphere:
390
W m
−
2
+
67
W m
−
2
+
…
+
…
=
324
W m
−
2
+
235
W m
−
2
390
W m
−
2
+
67
W m
−
2
+
78
W m
−
2
+
24
W m
−
2
=
324
W m
−
2
+
235
W m
−
2
559
W m
−
2
=
559
W m
−
2
Answer:
The sources that make up the deficit are evapotranspiration (
78
W m
−
2
) and thermals (
24
W m
−
2
) →
heating sources
2) Surface:
324
W m
−
2
+
168
W m
−
2
=
390
W m
−
2
+
…
+
…
324
W m
−
2
+
168
W m
−
2
=
390
W m
−
2
+
78
W m
−
2
+
24
W m
−
2
492
W m
−
2
=
492
W m
−
2
Answer:
The sources that make up the deficit are evapotranspiration (
78
W m
−
2
) and thermals (
24
W m
−
2
) →
cooling sources
d.
What percentage of the incident sunlight is absorbed by the atmosphere? (1.5 pts)
According to the class material:
Incident sunlight absorbed = Solar radiation (downwards) - Reflected solar radiation
Incident sunlight absorbed = 342
W m
−
2
−
107
W m
−
2
∴
Incident sunlight absorbed
=
235
W m
−
2
Percentage of incident sunlight absorbed:
incident sunlight absorbed
solar radiation
(
downwards
)
=
235
W m
−
2
342
W m
−
2
×
100%
=
68.71%
e.
What would happen to the radiation emitted downward by the atmosphere if the concentration of a greenhouse gas was suddenly increased? Explain why. (1pt)
If the concentration of a greenhouse gas in the atmosphere was suddenly increased, it’s more likely to generate a big greenhouse effect. This means that in the presence of this gas, the atmosphere would trap more of the outgoing radiation emitted by the Earth's 3
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surface, and consequently, if less radiation escapes into space, this would be a major contributor to global warming.
f.
Would the surface temperature rise or fall in response to the increase in greenhouse gas concentrations? Explain why. (1pt)
The surface temperature would rise in response to the increase in greenhouse gas concentrations
. As we have seen in the class material, greenhouse gases are known to trap heat in the Earth's atmosphere by absorbing and re-emitting radiation
. When their concentrations increase, they create a greenhouse effect, which prevents some of the heat from escaping into space. This trapped heat would lead to an overall warming of the planet, causing surface temperatures to rise
. g.
Would tropospheric temperatures rise or fall in response to the increase in greenhouse gas concentrations? Explain why. (1pt)
Tropospheric temperatures would rise
in response to an increase in greenhouse gas concentrations. The troposphere, being the lowest layer of the Earth's atmosphere, contains the majority of greenhouse gases. So, when the concentration of greenhouse gases increases, they amplify the
greenhouse effect
throughout the troposphere (and therefore also increase the temperature within the troposphere). 2.
Describe how the increase in carbon dioxide concentrations observed over the last
two centuries can be attributed to the burning of fossil fuels. List two observations
that have been used in this attribution. Include an explanation of the mechanism that caused the variations in each of the observations. (1.5pts)
We know that when fossil fuels are burned, they undergo combustion reactions that produce CO2 as a product. For that reason, all this amount of CO2 is released into the atmosphere and it accumulates over time.
Historical records:
They reveal a substantial surge in fossil fuel consumption, including coal, oil, and natural gas, driven by industrialization and growing energy needs since the 18th-century industrial revolution. This increased combustion of fossil fuels releases CO2
as a byproduct, and the emissions from these activities closely correspond to the rise in atmospheric CO2 levels.
Presence of isotopic forms of carbon in the atmosphere
: Carbon comes in different isotopes, with carbon-12 (12C) and carbon-13 (13C) being common stable forms. Fossil fuels have a lower 13C/12C ratio compared to the atmosphere. As more fossil fuels are burned, the release of 12C-rich CO2 into the atmosphere reduces the 13C/12C ratio. Measured declines in this ratio within atmospheric CO2 align with fossil fuel combustion
as the primary source. These two lines of evidence strongly link rising CO2 levels to human activities, particularly the burning of fossil fuels.
4
3.
Calculate the radiative forcing from a Solar Radiation Change (
ΔF)
: (1.5pts)
Initial Solar Irradiance: 1361 watts per square meter (W/m
2
)
New Solar Irradiance: 1359 W/m
2
C
dT
dt
=
F
SW
t
=
0
−
F
L W
t
=
0
=
0
C
dT
dt
=
F
SW
t
=
0
−
F
LW
t
=
0
+
ΔF
ΔF =
F
LW
t
=
0
+ F
SW
t
=
0
ΔF =
(1361 W/m
2
- 1359 W/m
2
)
Answer:
ΔF = 2
W/m
2
4.
How do aerosols impact radiative forcing? (1 pt)
Aerosols have an effect on the balance between incoming solar radiation (shortwave) and
outgoing thermal radiation (longwave) from the Earth's surface and atmosphere. Aerosols
are tiny solid or liquid particles suspended in the atmosphere, so they can influence radiative forcing in different ways, such as “aerosol-cloud interactions”
in which aerosols can modify the structure and properties of clouds. For example, certain aerosols can invigorate convective cloud systems, leading to taller and more intense clouds that may affect the distribution of precipitation and radiative balance. 5
REFERENCES
Leibniz Institute For Tropospheric Research. (2023). Radiative forcing of aerosols
. https://www.tropos.de/en/institute/departments/modeling-of-atmospheric-
processes/aerosol-strahlungs-wechselwirkung#:~:text=Atmospheric%20aerosol
%20particles%20directly%20affect,the%20atmosphere%20and%20cloud
%20properties.
Science & Information For a Climate - Smart Nation. (2023). Climate Change: Atmospheric Carbon Dioxide. https://www.climate.gov/news-features/understanding-climate/climate-change-
atmospheric-carbon-dioxide#:~:text=Carbon%20dioxide%20concentrations
%20are%20rising,in%20just%20a%20few%20hundred.
United States Environmental Protection Agency. (2022). Climate Change Indicators: Atmospheric Concentrations of Greenhouse Gases. https://www.epa.gov/climate-
indicators/climate-change-indicators-atmospheric-concentrations-greenhouse-
gases#:~:text=Concentrations%20of%20these%20greenhouse
%20gases,1%20billion%20molecules%20of%20air.
6
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