ESSEA Final Project part 2 - CSA

Causal Chains

1. E > A > B

A hurricane is often accompanied by a phenomenon known as a “storm surge.” The winds of a hurricane tend to be most intense in the right-forward quadrant of the storm. This is a result of adding together the speed and direction of the winds associated with the hurricanes: the movement of the storm itself over the earth, and the spiraling-inward winds. When these two motions are in the same direction, their wind speeds add together, reinforcing each other. This combined wind can push a large amount of water onshore and cause extensive wind damage to structures and life along the coast.

When a hurricane is out in the open ocean, the ocean’s surface bulges upward a bit – a few feet – under the eye of the hurricane because of the lower atmospheric pressure within the eye of the storm. This bulge increases in height as it comes into progressively shallower water much as any ocean wave gains height as it enters shallower water. The storm surge is often the most damaging aspect of the hurricane, producing massive and sustained flooding over a wide area and impacting animal and plant life.

2. E > A > E > A > . . .
Hurricanes transfer large amounts of energy, heat and moisture from the ocean into the atmosphere.
http://www.sciencedaily.com/releases/2005/01/050110114115.htm
The temperature of a substance is a relative measure of the average kinetic energy of the particles within the substance. Thus, water at 30^oC will have a normalized distribution of slow, average, and fast particles. These faster particles can attain enough energy to escape the liquid state completely and evaporate. Of course, as the temperature of the substance increases, more particles will gain enough energy to escape into the vapor stage.
Normally, this evaporation – escape of higher-energy water particles – results in lowering the average kinetic energy of the particles left behind in the liquid state. Hence, the phenomenon of evaporative cooling. Effectively, the water vapor has carried some of the energy from the ocean into the atmosphere.
As the mass of air containing this water vapor rises into the atmosphere, it undergoes expansion as it encounters the decreasing atmospheric pressure at higher altitudes. As the air mass expands, it cools, and the water vapor condenses back into the liquid state. Each kilogram of water that condenses releases 3.30 x 10⁵ J back into the atmosphere – almost 80 times the amount of energy required to change the temperature of that one kilogram of water by 1^oC. This relatively massive amount of energy is released into the surrounding atmosphere and tends to add energy to the ocean surface below, resulting in increased evaporation rates.. This energy also causes increased wind speed, which encourages further evaporation from the surface by breaking the surface into smaller droplets. Increased evaporation carries more energy into the atmosphere, releasing more energy as the latent heat of condensation. The hurricane acts as a system in resonance with each event reinforcing the effects of the other events.

3. E > H > A

When wind speeds increase, ocean turbulence increases, resulting in greater rates of evaporation from the ocean surface. As wind speed increases, the amount of ocean spray increases; this spray is simply the ocean surface broken up into smaller volumes. As the surface area of a given mass of water increases, it becomes more likely that water particles can escape the liquid state because they’re now nearer the surface of the water.

For example, one cubic meter of water measures 1 m x 1 m x 1 m. The surface of this cubic meter of water is 6 x (1 m x 1 m) = 6 m² of surface area. On the other hand, if this much water is broken up into cubic centimeters, there will be (100 cm x 100 cm x 100 cm) = 10⁶ cm³ of water. The surface area for each of these tiny packages of water is 6 x (10^-2 m x 10^-2 m) = 6 x 10^-4 m². Multiply this surface area per cm³ by 10⁶ of these cubes, and there are 6 x 10² m² of surface area – 100 times as much surface area, and now the same number of water particles (remember, the mass of water didn’t change, it was just re-packaged) will be much closer to the surface and more likely to be evaporated.

4. E>B>A>H

High wind speeds produce large ocean waves, which in turn can damage the framework of coral reefs. The amount of damage to massive corals is slight, but more delicate coral structures can face 99% damage.
http://www.int-res.com/articles/meps/78/m078p201.pdf

Coral reefs act as large carbon sinks. As coral reefs are destroyed, less carbon can be stored in the ocean and more is available to the atmosphere, resulting in increased concentrations of CO₂ and increased atmospheric temperatures. These increased atmospheric temperatures result in increased ocean temperatures, which may increase the intensity of hurricanes.

5. E > B > A

53% of the US population and 55% of the world’s population lives within 50 miles of a coastline. This increase in development and property values means that even if hurricanes do not change in frequency or intensity, we still face horrific costs with each successive hurricane. Low-lying, developing countries such as Bangladesh and India face increased risk of large numbers of human fatalities if there’s an increase in hurricane frequency or intensity.
http://www.noaanews.noaa.gov/stories2007/s2811.htm ; http://www8.nos.noaa.gov/nccos/npe/projectdetail.aspx?id=61&fy=2007

When nations must be concerned more about protecting their citizens from imminent and frequent flooding, they will be less concerned with regulating their carbon emissions.

6. E > B > B

A hurricane can strip coastal forests of branches and leaves, uproot trees with weak root systems, and the resulting leaf litter on the forest floor can choke out the undergrowth. The torrential rainfall can produce mudslides which in turn devastate an area’s ecology. Water left standing can contribute to increased mosquito populations and the accompanying malaria & dengue fever.
http://emissionhq.com/2weeks/hitsPuertoRico.aspx

DDT is still the insecticide of choice (National Geographic, August 2007) for eradicating malaria-bearing mosquitoes. If nations use more DDT, the biosphere will undergo other changes in the quantity and quality of its waterfowl a la Rachel Carson’s “Silent Spring.”

7. B > E > A > H

In the past, coastal wetlands have served as buffers between hurricanes and populated areas. With the coastal wetlands disappearing at a rate (in Louisiana) of 25 square miles per year, populated areas will see more damage and fatalities from hurricanes even if the intensity and frequency of hurricanes does not increase.
http://www.washingtonpost.com/wp-dyn/content/article/2005/11/10/AR2005111000138_pf.html

Likewise, as wetlands are replaced with developments, an area loses its capability for carbon sequestration. This lack can lead to increased concentrations of CO₂ in the atmosphere, resulting in increased global temperatures in the atmosphere and then in the oceans. These increased temperatures could help increase the intensity of hurricanes.

8. H > L > B

Rainfall causes increased water flow resulting in increased erosion. In turn, this leads to greater sediment levels in the rivers which are deposited as the velocity of the water decreases downstream. The good news is that this increased sediment load can help buoy up sinking river deltas. On the other hand, the Mississippi’s sediment load has decreased by 25% over the past several decades, and the Mississippi River delta – upon which the city of New Orleans is located – is sinking as a result. This in turn leads to the potential for more damage from the storm surges that accompany hurricanes.

9. L > A > L > A . . .
Eroded, barren land can give up more dust into the atmosphere, providing more condensation nuclei for water vapor. Greater precipitation over these areas will result in even more erosion, exacerbating the problem.

10. H > A > H > A . . .

The warm ocean water provides water vapor to the atmosphere, and its condensation provides energy for further evaporation of water from the ocean surface. This feedback loop, aided by lack of wind shear in the upper atmosphere, provides the impetus for hurricane formation and intensification.

ESSEA Final Project Part I- CSA

Event-Sphere and Sphere-Sphere Interactions

Event and Atmosphere: Hurricane

E > A
Hurricanes transfer large amounts of energy, heat and moisture from the ocean into the atmosphere.
http://www.sciencedaily.com/releases/2005/01/050110114115.htm
Energy is needed to change water from a liquid to vapor, and as water evaporates it transfers energy from the ocean to the atmosphere.

E > A
Hurricanes produce large variations in atmospheric pressure across the radius of the storm, with the lowest pressure present in the central ‘eye’ of the storm. Hurricane strength is measured in terms of maximum sustained wind speed and the barometric pressure within the eye. Lower barometric pressures result in greater wind speeds because the wind is a result of the air moving from a region of higher pressure to a region of lower pressure. As the pressure gradient increases, so does the wind speed. This phenomena can be compared to siphoning gas from a car tank: as the mouth-sucking end of the hose is lowered, the gas comes out faster. The Coriolis effect then causes the familiar spiral formation as the inward-rushing winds are acted upon by the earth’s rotation. Contrary to popular opinion, the Coriolis effect is not the factor influencing short-term phenomena such as water swirling down a drain. The Coriolis forces act over a large area over a relatively long time.

A > E
Presence of high wind shear in the upper atmosphere prevents hurricanes from forming.
http://environment.newscientist.com/channel/earth/hurricane-season/dn11633-wind-shear-may-cancel-climates-effect-on-hurricanes.html

In order for the cycle of evaporation-rising altitude-condensation-release of energy to occur, lateral wind currents at the upper atmosphere must be minimal. This is because wind shear would cause the energy to dissipate and disrupt the flow of winds rushing in to the center of low pressure at the eye of the storm.

A > E
Hurricanes form when energy is released into the atmosphere from the condensation of water vapor in the upper atmosphere. It seems to follow that increased ocean temperatures will promote increased evaporation of water from the ocean into the atmosphere, providing a greater amount of energy that could be used to form or intensify hurricanes.
http://www.physicstoday.org/vol-59/iss-8/p74.html

Event and Hydrosphere: Hurricane

E > H
As hurricanes pass over open warm water, energy is released from the water into the hurricane leaving a region of much cooler water in the storm’s wake. This follows the law of conservation of energy – that energy entering one part of a closed system had as its source another part of the closed system. True, the earth isn’t a closed system, but the regions of water surface/overlying air could be considered as such over a fairly large area.

H > E
Increased ocean temperatures lead to increased rates of surface evaporation, which in turns provides more energy to fuel the hurricane’s development.

Event and Biosphere: Hurricane

E > B
Hurricanes stir up the ocean, resulting in phytoplankton blooms forming in their wake.
http://www.nasa.gov/centers/goddard/news/topstory/2004/0602hurricanebloom.html

As hurricanes stir up the oceans over which they pass, nutrients are brought up from the depths. Phytoplankton which depend on these nutrients can now access them in the zones of light upon which they’re dependent, resulting in increased populations of phytoplankton. The magnitude of these blooms depends on the size, strength, and duration of the hurricanes.

E > B
High wind speeds produce large ocean waves, which in turn can damage the framework of coral reefs. The amount of damage to massive corals is slight, but more delicate coral structures can face 99% damage.
http://www.int-res.com/articles/meps/78/m078p201.pdf

E > B
53% of the US population and 55% of the world’s population lives within 50 miles of a coastline. This increase in development and property values means that even if hurricanes do not change in frequency or intensity, we still face horrific costs with each successive hurricane. Low-lying, developing countries such as Bangladesh and India face increased risk of large numbers of human fatalities if there’s an increase in hurricane frequency or intensity.
http://www.noaanews.noaa.gov/stories2007/s2811.htm ; http://www8.nos.noaa.gov/nccos/npe/projectdetail.aspx?id=61&fy=2007

E > B

A hurricane can strip coastal forests of branches and leaves, uproot trees with weak root systems, and the resulting leaf litter on the forest floor can choke out the undergrowth. The torrential rainfall can produce mudslides which in turn devastate an area’s ecology. Water left standing can contribute to increased mosquito populations and the accompanying malaria & dengue fever.
http://emissionhq.com/2weeks/hitsPuertoRico.aspx

B > E
In the past, coastal wetlands have served as buffers between hurricanes and populated areas. With the coastal wetlands disappearing at a rate (in Louisiana) of 25 square miles per year, populated areas will see more damage and fatalities from hurricanes even if the intensity and frequency of hurricanes does not increase.
http://www.washingtonpost.com/wp-dyn/content/article/2005/11/10/AR2005111000138_pf.html

Event and Lithosphere: Hurricane

E > L
Extreme amounts of rainfall can result in mudslides and substantial erosion of beaches and coastal plains. Rivers can carve new channels due to their increased discharge.
http://emissionhq.com/2weeks/hitsPuertoRico.aspx

.

Sphere-Sphere Interactions: Hurricane

Lithosphere<=> Hydrosphere

Rainfall causes increased water flow resulting in increased erosion. In turn, this leads to greater sediment levels in the rivers which is deposited as the velocity of the water decreases downstream. The good news is that this increased sediment load can help buoy up sinking river deltas. For example, the Mississippi’s sediment load has decreased by 25% over the past several decades, and the Mississippi River delta – upon which the city of New Orleans is located – is sinking as a result.

Lithosphere <=> Biosphere

Eroded land and missing topsoil is less likely to support plant life, resulting in more erosion because there are no roots to keep the soil in place.

Lithosphere <=> Atmosphere

Eroded, barren land can give up more dust into the atmosphere, providing more condensation nuclei for water vapor. The mere presence of water vapor at the right temperature and pressure is not enough for condensation to occur; the vapor needs a tiny bit of matter to cling to such as dust or smoke particles or sea salt from ocean spray. Hence, cloud seeding is used to “kick-start” rainfall in some areas. The effect is analogous to “bubbles in a glass of beer.” Sure, a good, fresh beer is nice and frothy because the bubbles are speeding to the surface . . . but try adding some salt! Yes, it ruins the taste, but just watch the froth magnify because the gas that’s dissolved in the liquid now has something to congregate around (nuclei), and the bubbles grow as they rise to the surface because more and more gas microbubbles are attracted to the larger bubble. I’d thought this growth was explained by the decreased pressure within the liquid as the depth below the surface decreased; if you do the math, though (was it Stokes theorem? Sorry, it’s been awhile, don’t remember the details), that factor doesn’t begin to account for the growth of the bubbles.

Hydrosphere <=> Biosphere

Changes in water reservoirs lead to changes in the life in and surrounding them. As water evaporates, the sediment load increases proportionately and fish species preferring clear water die out, leaving traditional bottom-feeders such as catfish, carp and gar.

Hydrosphere <=> Atmosphere

This is probably the most significant sphere-sphere interaction in the hurricane. The warm ocean water provides water vapor to the atmosphere, and its condensation provides energy for further evaporation of water from the ocean surface. This feedback loop, aided by lack of wind shear in the upper atmosphere, provides the impetus for hurricane formation and intensification. H > A > H > A . . .

Biosphere <=> Atmosphere
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