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Oceans and Man. Oceans and Human Habitation of Earth Ocean role in moderating earths climate cannot be overstated (high specific heat of water!) Biochemically.

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Presentation on theme: "Oceans and Man. Oceans and Human Habitation of Earth Ocean role in moderating earths climate cannot be overstated (high specific heat of water!) Biochemically."— Presentation transcript:

1 Oceans and Man

2 Oceans and Human Habitation of Earth Ocean role in moderating earths climate cannot be overstated (high specific heat of water!) Biochemically we cannot live without the ocean (salt) Oceans are the last large hunter-gatherer realm where food is taken and nothing returned Mariculture/Aquaculture- (ocean ranching and farming) is in its infancy but growing steadily In addition to fish, mineral resources of the oceans are fabulous (oil/gas, minerals, energy) Despite all of the above, oceans have been and still are dumping grounds for all of history

3 Oceans and Man Coastal issues (erosion, shoreline engineering, terraces) Weather systems derived from oceans (hurricanes, typhoons, El Niño) Tides Fisheries-Mariculture –ocean farming (oysters) ocean ranching (salmon) Ocean law (EEZ) flag approach Military/Political (straits issue) Ocean pollution (5 types & prognosis) Petroleum resources from the oceans

4 Coastal Erosion & Sediment Movement Rising global sea level due to warming ~1mm/yr (eustatic-more water in oceans) Rising/falling sea level due to local tectonics (in Oregon ~1/2/yr) raised terrace development The sand budget (longshore drift, loss of sediment to shelf, gain from land) Longshore drift & sedimentation (groins, jetties) Rip tides (the rare places where waves approach a coast at close to a right angle) Coastal landslides-chronic because toe of slide is continously being removed by wave action

5 Movement of offshore sand bars The following three images track the movement of sand offshore from Mass. The spit or sand mass in the picture was stable for several years and featured summer homes accessible from the mainland by a narrow road A single winter storm radically changed the spits geometry, cut it off from the mainland and washed away almost 80% of its area Today the spit is accessible only by boat

6 Coastal Engineering Problems arise at active ocean margins where sea level is changing rapidly and along margins where cultures have built right up to the waters edge (crises arise mainly with severe storms) Construction types: all ephemeral and require constant maintainence and redesign –Rip rap (rock or concrete block armor) –Breakwaters –parallel to shoreline (to beak up waves) –Groins & jetties-at right angles to shore (to retard & slow longshore movement of sediment) –Seawalls (to slow erosion, easily undermined)

7 Coastal Engineering Most coastal engineering projects unless very carefully designed seem the have an effect opposite of that desired…….. there are perhaps only a half dozen competent coastal engineers Many such works function but the adjacent properties get the problem you just solved! ( best example is groins!) All coastal engineering works must be regarded as temporary or a stop-gap measure ( the erosive power of the ocean is unlike anything in the terrestrial realm! …think storms)

8 Terraces Are typical of tectonically active coasts where the land is being elevated After a sector of sea floor is shaved flat by wave erosion it may be elevated above sea level These flat surfaces are natural sites for all manner of cultural activity from highways to entire cities With continued elevation of the land, successive terraces develop in a stair step fashion These terraces are configured with the oldest at the highest elevation and youngest at the base

9 Weather Systems Many names for the same weather phenomenon –Hurricane (Atlantic) –Typhoon (Pacific) –Cyclone (Indian) –Willy Willy (Australia) Monsoons (mainly due to height and size of Tibetan plateau and Himalayas

10 The recipe for a Hurricane 1.After a long, hot summer equatorial waters are very warm >80° F 2.This very warm water evaporates rapidly and a huge amount of heat in moisture laden clouds is trapped at the equator in the lower atmosphere near the sea surface. The warm wet air begins to escape like steam as it vents to the upper atmosphere The escaping air spins to left in N. Hemisphere & right in S. Hemisphere (due to Coriolis effect) Rotating winds reach speeds >180 mph and storm systems pushed by strong trade winds begin to move following a western path curving to the NW (due again to Coriolis)

11 Hurricane Systems Anvil shaped & extend from 5-40 miles high in the atmosphere with a base 150 miles or more wide (humongous!) Energy is drawn from sea, as the storm system moves ashore it rapidly wanes The most destructive hurricanes move parallel to a shore line maintaining their energy from the ocean as they chew up the coast

12 Monsoons I, winter Arabic word masium means season Created by air masses rising and descending over the elevated mass of the Himalayas & Tibetan Plateau displacing the I.T.C.Z. Winter months- a major high pressure system develops over the Himalayas where descending heavy cold air pushes the NE trades to the south well out over the Indian ocean

13 Monsoons II, summer In hot summer months- warm air rising off the Himalayas disrupts the NE trades and strong, moisture-laden SW winds are pulled to the north. As this air mass gets to the Himalayan mountains it rises, cools and begins to deliver torrential rains to the Indian subcontinent and N. Indian Ocean (the monsoon). At the top of the funnel shaped ocean basin the mouths of the Ganges, Indus and Brahmaputra Rivers lie between fluvial runoff from the north & a blister of water [storm surge] from the south with resulting catastrophic flooding to the deltas.

14 Tides (how Nature flushes the toilet) Pull of moon and sun-lunar/solar (proximity is everything) Spring tides – Earth, Moon, Sun all line up Neap tides – Moon/Sun at right angles from Earth Moons elliptical orbit apogee/perigee difference ~16,000 miles and tidal attraction difference is ~20%! Highest tides would be spring tides when moon & sun line up and moon is closer to earth at perigee in phase Coastal configuration can cause funnel effect with very high/low tides (Bay of Fundy, Nova Scotia) Large estuaries get rotational motion as tides move across to remove waste and bring in fresh seawater.

15 Tides and Latitude Diurnal – one low, one high tide in 24 hours (in high-latitudes) Semi-diurnal – 2 low and 2 high tides of equal size in 24 hours (moon is right over equator) (low latitudes,Mid-Atlantic) Mixed – 2 high and 2 low tides of varying sizes in 24 hours (mid latitudes,) Seattle, Honolulu

16 Power from Tides To date there are not on-line functioning power generating tidal systems in North America. The La Rance estuary in France works like a hydroelectric system where incoming tidal water is trapped then released through turbines to generate power. The La Rance system is a model for its efficiency and low cost to operate. It is estimated that the bay of Fundy has twice to three times the potential of La Rance. Hmmmmmmmmmmmm……….

17 Major Fisheries in World Oceans Only 4 ocean areas make up 2/3 of total fisheries ! –South American west coast – Peru/Humbolt Current (anchovies) >10% of total –NE Atlantic Ocean (North Sea) [ground fish and pelagic fish] 16% –NW Pacific – Oyashio cold south bound surface current out of Bering Sea 31% ! –West Central Pacific- ~9 % –With such a lopsided distribution, conflict is inevitable

18 Global Fish Harvest Japan, former Soviet Union & China big winners Peru anchovy harvest for fish meal fertilizer (crashes during El Niño) Capture vs Aquaculture fisheries (former in stasis, latter increasing ~10%/yr) By ocean, of ~95 million tons; 2/3 is Pacific; ¼ is Atlantic; 1/20 is Indian; & 1/5 is marginal and inland seas Bering Sea donut hole (refuge for boats fishing illegally)

19 Politics and Oceans Concept of the high seas Ineptitude of the U.N. as a governing body (pollution, whaling, mining, fisheries), [a miserable legacy!] E.E.Z. claims, ~200 miles and covering everything, (passage, fisheries, mining etc), flag approach Straits issues-all attention focused on the Indian ocean because it is the oil tanker route……… Ocean ranching and lack of international cooperation National Lake solution-tried in Antarctica & failed, no equity for small, land-locked nations (area?, population?, wealth?, military might?, historic claims?)

20 Major Straits Narrow passages guarded by missiles, artillery or land-based aircraft Choke points where sea traffic can be easily monitored & disrupted [most are of historic note only] today Indian Ocean is a main focus because of oil supply out of that seaway. Atlantic- –Dover, Gibraltar, Barents Sea, Baltic mouth, Drake Passage, Panama Canal, Cape of Good Hope Mediterranean – –Gibraltar, Bosporus, Suez Pacific- –Bering, Timor Sea, Drake Passage, Tasman Sea Indian- –Bab, El Mandeb, Hormuz, Sunda, Malacca/Singapore, Timor Sea

21 Pollution Defined as: release (or extraction) by man of a product into the environment that is deleterious (does not apply to red tides, freezes or volcanic emissions) Bulk dumping –dredge spoils, nuclear by-products, explosives Phosphates & related nutrients-(sewage!) Heavy metals – Hg, Pb, Cu, (bioaccumulation) Petroleum production, transport, refining, use of & by- products (plastics) Chlorinated hydrocarbons (PCBs – DDT)

22 Pollution Defined as: release or extraction by man of a product into the environment that is deleterious (does not apply to red tides, freezes or volcanic emissions) Bulk dumping –dredge spoils, nuclear by- products, explosives Phosphates & related nutrients-sewage Heavy metals – Hg, Pb, Cu, (bioaccumulation) Production and transport of petroleum & by- products (plastic) Chlorinated hydrocarbons (PCBs – DDT)

23 Mercury Levels in Fish Unsafe Fish –Swordfish –Shark –King Mackerel –Tilefish Some Safe Fish –Catfish –Cod –Salmon –Tilapia –Trout –Tuna (light chunk) –Whitefish

24 Petroleum Issues in Oceans Oil exploration & production focused on continental margins Oil pollution during production/transport (considerable !) Oil pollution is regarded as ephemeral despite the local disasters it creates Dispersion of oil after a spill or major shipwreck follows a set pattern

25 Gas/Oil Seeps in the Oceans Common along all passive margins and many active margins Provide energy and food for marine organisms so there are multiple oases Seeps eventually heal-over and seal & gilsonite plugs the fracture The short and long term ecologic damage is minimal because organisms live off the seep & input is comparatively slow

26 Types of Platforms for Oil Production Jack-up rigs – upper continental shelves down to 200-300 feet- cheap but have serious stability problems Ferro-concrete submersibles- common in North Sea off Britain can withstand hurricanes, 1000-2000 of water MARS platform- up to 3000 water, wired in by cables, can stand 145 mi/hr hurricane force winds Semi-submersibles- hunkers down over hole up to 3000-4000, can move off quickly in a storm, cabled and anchored L.D.V. (large drilling vessels) in water up to 7000 deep, dynamically positioned All of the above use risers and B.O.P.s

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