We will concentrate on the use of a simple Fortran computer model for climate sensitivity data to explore the theoretical effects of climate change on different aspects of our society. We will specifically look at how changing evaporation while precipitation remains constant affects agricultural crop yield. Other aspects of this model could be used to investigate effect on reservoir and lake levels, soil moisture, and economics.
Coefficient of Precipitation Change = bb (This variable remained constant at 0.03)
Coefficient of Evaporation Change = aa (This variable has three separate values)
|
Variable |
Value |
Interpretation of Variable Change |
|
aa |
0.04 |
Increases the amount of evaporation by increasing the amplitude of the evaporation curve as compared to the constant precipitation curve. |
|
aa |
0.03 |
The amount of evaporation is the same as the amount of precipitation. Both curves have the same amplitude. |
|
aa |
0.02 |
Decreases the amount of evaporation by decreasing the amplitude of the evaporation curve as compared to the constant precipitation curve. |
Magnitude of Evaporation Change = yy = (This variable has 3 separate values.)
|
Variable |
Value |
Interpretation of Variable Change |
|
yy |
0.01 |
Increases the amount of evaporation change across the entire year. |
|
yy |
0.00 |
No change in magnitude. |
|
yy |
-0.01 |
Decreases the amount of evaporation change across the entire year. |
Delayed Timing of Evaporation Change = xx = (This variable has five separate values)
|
Variable |
Value |
Interpretation of Variable Change |
|
xx |
pi/2 |
Peak evaporation has the same onset as peak precipitation. |
|
xx |
9*pi/16 |
Peak evaporation is delayed » 15 days after precipitation peak. |
|
xx |
2*pi/3 |
Peak evaporation is delayed » 30 days after precipitation peak. |
|
xx |
3*pi/4 |
Peak evaporation is delayed » 45 days after precipitation peak. |
|
xx |
pi |
Peak evaporation is delayed » 90 days after precipitation peak. |
|
Graph Series |
Coefficient Evaporation (aa) |
Magnitude Evaporation Change (yy) |
Delayed Timing in Days (xx) |
Estimated Percent Crop Yield (%) |
Graphs |
|
|
0.02 |
0.01 |
0 (pi/2) |
-38 |
|
|
|
0.02 |
0.01 |
15 (9*pi/16) |
-45 |
Click to see |
|
1 |
0.02 |
0.01 |
30 (2*pi/3) |
-56 |
|
|
|
0.02 |
0.01 |
45 (3*pi/4) |
-64 |
|
|
|
0.02 |
0.01 |
90 (pi) |
-80 |
|
|
|
0.02 |
-0.01 |
0 (pi/2) |
29 |
|
|
|
0.02 |
-0.01 |
15 (9*pi/16) |
22 |
Click to see |
|
2 |
0.02 |
-0.01 |
30 (2*pi/3) |
11 |
|
|
|
0.02 |
-0.01 |
45 (3*pi/4) |
2 |
|
|
|
0.02 |
-0.01 |
90 (pi) |
-14 |
|
|
|
0.04 |
0.01 |
0 (pi/2) |
-29 |
|
|
|
0.04 |
0.01 |
15 (9*pi/16) |
-42 |
Click to see |
|
3 |
0.04 |
0.01 |
30 (2*pi/3) |
-65 |
|
|
|
0.04 |
0.01 |
45 (3*pi/4) |
-82 |
|
|
|
0.04 |
0.01 |
90 (pi) |
-114 (total) |
|
|
|
0.04 |
-0.01 |
0 (pi/2) |
38 |
|
|
|
0.04 |
-0.01 |
15 (9*pi/16) |
24 |
Click to see |
|
4 |
0.04 |
-0.01 |
30 (2*pi/3) |
2 |
|
|
|
0.04 |
-0.01 |
45 (3*pi/4) |
-15 |
|
|
|
0.04 |
-0.01 |
90 (pi) |
-47 |
|
To read the graphs:
- Compare the amount of area between the two curves.
- When the upper curve is precipitation and the lower curve is evaporation, there is a net gain or surplus of water resources (precipitation > evaporation). This area is shaded blue to allow for easier interpretation of the graphs.
- When the upper curve is evaporation and the lower curve is precipitation, there is a net loss or deficit of water resources (precipitation < evaporation). This area is shaded red to allow for easier interpretation of the graphs.
- The area of deficit needs to be compared to the area of surplus to determine the overall amount of available water.
- If the area of deficit is greater than the area of surplus, then the overall amount of water available for agricultural crops is very low, which would lead to a decrease in the crop yield.
- If the area of surplus is greater than the area of deficit, then the overall amount of water available for agricultural crops would be higher resulting in a larger crop yield.
When viewing each separate series, note that the time delay of the evaporation curve peak increases as compared to the precipitation curve peak. As the time delay increases, the area of deficit (precipitation < evaporation) increases. This produces a greater reduction in crop yield across any single series.
The main cause increased evaporation is due to an increase in temperature as a result of global warming. Increased air temperature leads to an increase in the amount of water vapor in the atmosphere. This increase in evaporation leads to drier regions. General Circulation Models show that as a result of this increase, the frequency of precipitation decreases, while its intensity increases. Not only does this lead to localized flooding, but increased erosion.
