THE OCEAN, MOTHER OF ALL WATERS
by
Chris Maser

Although water arrives in the oceans of the world from various sources and in a variety of ways, as illustrated in the foregoing discussion of submarine springs of continental groundwater, glacial discharge is another mode of entry. Basal motion of glaciers is responsible for short-term variations in glacier velocity. As sub-glacial water passes through a series of dynamic conduits that are fed by a system of linked cavities in the ice-bedrock interface, it plays a critical role in setting the rapidity with which a glacier moves. An increase in forward motion takes place whenever inflowing water exceeds the ability of the existing conduits to release the water, at which time the conduits pressurize and drive water back into the already extensively linked cavity system. The outcome of this self-reinforcing feedback loop is accelerated calving (breaking off) of a glaciers' marine terminus, which leads to accumulating chunks of ice floating in the ocean, and thus is tightly connected to a rise in sea level.1

  

The Pacific Ocean off the Oregon Coast and the Sea of Japan at Tagata, Hirihito, Japan.

Now the analysis of an oceanic sediment core from the the Lomonosov ridge in the central Arctic (about 155 miles, 250 kilometers, from the North Pole) reveals vast quantities of well-preserved fossils of the needle-like diatom Synedropsis spp., at about 853 feet (260 metres) below the sea floor—a diatom that relied on sea ice for its survival. It is critical to differentiate sea ice from land-based glacial ice because climate feedback mechanisms vary and global impacts differ between these systems: sea ice directly affects ocean-atmosphere exchanges, whereas land-based ice affects sea level and consequently oceanic acidity.

Existence of the fossil diatom, in combination with the a detailed analysis of the particle size composing the sediment, indicates that sea ice was the dominant source of ice-rafted debris around the middle Eocene epoch, 47.5-45.5 million years ago. This evidence pushes the first appearance of sea ice in the Arctic back by 1.25 million years, and the first appearance of sea-ice diatoms by 16 million years.2 Moreover, melting sea ice would also contribute to rising sea levels.

According to two studies, there is widespread evidence that the sea-level highstand (the level at which the sea lies above the edge of the continental shelf) was 13 to 20 feet (4 to 6 meters) higher 121,000 years ago, during the last intergalcial period, than it is today due to a significant contribution of water from the melting Greenland ice sheet. Moreover, data from fossil reefs of coral northeast of the Yucatan peninsula, Mexico, showed that oceans rose 6.6 to 10 feet (2 to 3 meters) within 50 to 100 years. Further, data from both planktonic foraminifera and coal from the central Red Sea exhibited an average rate of sea-level rise during the last interglacial period to have been 5 feet (1.6 meters) per century.3

If such a rise in sea level took place today due to the melting of both the Greenland and Antarctic ice sheets, such major coastal cities as New York (United States), Rio De Janeiro (Brazil), London (England), Tokyo (Japan), Calcutta (India), and Sydney (Australia) would be inundated. Herein lies a paradox, however, because the once-submerged coastline around Juneau, the captial of Alaska, is not only high and dry now but also turning into grassland—and eventually forest. The ground is lifting upward faster than the sea level can rise due to the reduced weight of the melting glacies in the mountains east of Juneau. A similar phenomenon is taking place around the glaciers in Greenland.4

  

The stream in the bottom of Kiger Gorge in the Steens Mountains of southeastern Oregon is fed by winter snow.  As the snow melts, it fills the stream, which flows into the South Fork of the Malhure River, which flows north into the main fork of the Malhure River.  The Malhure River originates in the southern Blue Mountains of northeastern Oregon and flows south, then southeast, and then, with the waters of the South Fork, it turns north and then east into the Snake River.  The Snake River, in turn, originates in Yellowstone National Park, Wyoming, from whence it flows through a series of mountain ranges, canyons, and plains into Hells Canyon along the Idaho-Oregon border and finally (in the state of Washington) into the Columbia River.  The Columbia River, in its turn, begins in British Columbia, Canada, from which it flows generally southward and then west into the Pacific Ocean as the fourth largest river in the United States.

On the other hand, the streams and rivers of the world are a more constant and diverse source of waters and materials draining into the oceans. For example, a mountainous river in the Austrian Alps would add only about 5 percent of its load of dissolved iron to coastal waters, whereas a small tributary draining a sphagnum peat-bog, which acts as a source of fulvic acids to the river water, would add approximately 20 percent of its original load of dissolved iron to the ocean's supply of biologically available iron. (Fulvic acid is a natural acid that can be extracted from the humus found in soil, sediments, or aquatic environments. Its name is derived from Latin fulvus, referring to its yellow color.) This is a natural, terrestrially derived mechanism of iron fertilization in an ocean that originates from the weathering processes occurring in the soils upstream.5

On a larger scale, the transfer of organic carbon from continents to oceans through erosion and the subsequent transportation by streams and rivers constitutes an important component of the global carbon cycle. More than one third of this organic carbon comes from sediment-laden rivers that drain the mountains in the western region of the Pacific Ocean, which is the largest of the oceanic divisions, encompassing almost a third of the Earth's surface. It has an area of 69.4 million square miles (179.7 million square kilometers), which is significantly larger than Earth's entire landmass. The irregular western margins of the Pacific Ocean encounters many seas: Celebes Sea, Coral Sea, East China Sea, Philippine Sea, Sea of Japan, South China Sea, Sulu Sea, Tasman Sean, and the Yellow Sea. This region is prone to tropical cyclones, whose floods carry large amounts of sediments made up of fragments from preexisting rock. Non-fossil, particles of organic carbon transported at the same time may be buried offshore under large accumulations of river-borne sediment.

Soil eroding into the Pacific Ocean along the Oregon Coast.

A study of the LiWu River in Taiwan demonstrates that, on decadal time scales, cyclone-triggered floods are responsible for 77 to 92 percent of non-fossil, organic carbon eroded from the LiWu water catchment and transported to the ocean. Thus, tropical cyclones (mediated by frequency, intensity, and duration), which affect many forested mountains within the Intertropical Convergence Zone or "Monsoon trough," may provide optimum conditions for the delivery and burial of organic carbon in the ocean.6

The Intertropical Convergence Zone is an area of low pressure that forms where the Northeast Trade Winds meet the Southeast Trade Winds near the Earth's equator. As these winds converge, moist air is forced upward, which causes water vapor to condense, or be "squeezed" out, as the air cools and rises. This condensation results in a band of heavy precipitation around the globe.7

Here, it is important to debunk a common euphemism applied to pollution that hides a basic truth and thus has tragic results—namely, "the answer to pollution is dilution." This euphemism is most often used in terms of pollution in streams and rivers. Bear in mind, however, that, while moving water can dilute chemicals put into it, they concentrate in "still" bodies of water, such as lakes, which are separate entities (Lake Baikal, Great Lakes, Lake Geneva, Lake Zurich, Lake Tanganyika), and oceans (Pacific, Atlantic, Indian, Red Sea, Coral Sea, Sea of Japan, Caspian Sea, Aegean Sea, Mediterranean), which have common connections.

  

There is yet another profound difference between lakes and oceans, however, in that most lakes have outlets, which allows inflowing water to flush them of pollutants to a greater or lesser degree, depending on the lake. Oceans, on the other hand, have no outlets, which means all incoming pollution is trapped and thus can only concentrate over time. Moreover, evaporation of the surface water from the world's oceans further concentrates the existing pollutants.

ENDNOTES

  1. (1) Timothy C. Bartholomaus, Robert S. Anderson, and Suzanne P. Anderson. Response of Glacier Basal Motion to Transient Water Storage. Nature Geoscience, 1 (2008):33-37; (2) H. Jay Zwally, Waleed Abdalati, Tom Herring, and others. Surface Melt-Induced Acceleration of Greenland Ice-Sheet Flow. Science, 297 (2002):218-222; (3) Eric Rignot and Pannir Kanagaratnam. Changes in the Velocity Structure of the Greenland Ice Sheet. Science, 311 (2006):986-990; (4) Alumt Iken & R.A. Bindschadler, R. A. Combined Measurements of Subglacial Water Pressure and Surface Velocity of Findelengletscher, Switzerland: Conclusions About Drainage System and Sliding Mechanism. Journal of Glaciology, 32 (1986):101-119; (5) H. Jay Zwally, Waleed Abdalati, Tom Herring, and others. Surface Melt-Induced Acceleration of Greenland Ice-Sheet Flow. Science, 297 (2002):218-222; and (6) Robert S. Anderson, Suzanne P. Anderson, Kelly R. MacGregor, and others. Strong Feedbacks Between Hydrology and Sliding of a Small Alpine Glacier. Journal of Geophysical Research, 109, F03005 (2004).

  2. The discussion of sea ice is based on: Catherine E. Stickley, Kristen St John, Nalân Koç, and others. Evidence for Middle Eocene Arctic Sea Ice from Diatoms and Ice-Rafted Debris. Nature, 460 (2009):376-379.

  3. (1) Paul Blanchon, Anton Eisenhauer, Jan Fietzke, and Volker Liebetrau. Rapid Sea-Level Rise and Reef Back-Stepping At the Close of the Last Interglacial Highstand. Nature, 458 (2009):881-884 and (2) E. J. Rohling, K. Grant, Ch. Hemleben, and others. High Rates of Sea-Level Rise During the Last Interglacial Period. Nature Geoscience, 1 (2008):38-42.

  4. Sea Level-Global Warming Paradox. May 22, 2009. Earthweek: A Diary of the Planet. http://www.earthweek.com/index.html (accessed on June 2, 2009).

  5. (1) R. Krachler, F. Jirsa, and S. Ayromlou. Factors Influencing the Dissolved Iron Input By River Water to the Open Ocean. Biogeosciences, 2 (2005):311-315 and (1) Fulvic acid. http://www.britannica.com/EBchecked/topic/221974/fulvic-acid (accessed on April 18, 2009).

  6. The foregoing two paragraphs are based on: (1) Robert G. Hilton, Albert Galy, Niels Hovius, and others. Tropical-Cyclone-Driven Erosion of the Terrestrial Biosphere From Mountains. Nature Geoscience, 1 (2008):759-762 and (2) Pacific Ocean. http://en.wikipedia.org/wiki/Pacific_Ocean (accessed on April 18, 2009).

  7. The Intertropical Convergence Zone (ITCZ). http://iri.ldeo.columbia.edu/~bgordon/ITCZ.html (accessed on April 18, 2009).


Evaporation from the oceans of the world waters the continents. So, remember the next time you take a shower that you are being rained upon by water from the world's oceans, and next time you take a bath be aware that you are bathing in the ocean—the mother of all waters.


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