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Oceans and climate - July 25

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From the Institute of Science in Society Special Miniseries: Save Our Oceans, Save Our Planet

Oceans in Distress

Mae Wan Ho, Institute of Science in Society
Pollution, destructive overfishing and increasing commercial exploitation are threatening the planet’s cradle of life, warns the UN. Dr. Mae-Wan Ho

Overfishing and pollution

Pollution and overfishing are damaging the oceans, especially the deep oceans, the United Nations warns in a new report [1-3]. Time is running out to save them, and urgent legislation is required to halt this wanton destruction of the planet’s “cradle of life”.

More than 90 percent of the earth’s living biomass (weight of living matter) is found in the oceans, and 90 percent of that is made up of single cell and microbial species. With 90 percent of the oceans yet to be explored, the scale of devastation already happening has become all too obvious

In 2005, 84.5 million tonnes of fish were taken from the world’s oceans, 100 million sharks and related species were butchered for their fins, 250 000 turtles got tangled up in fishing gear and 300 000 seabirds including 100 000 albatrosses were killed by illegal long-line fishing. Nineteen out of 21 albatross species are now threatened with extinction.

During the same period, 6.4 million tonnes of litter was thrown into the oceans, and 38 000 pieces of discarded plastic float on every square kilometre. There are up to 6 kg of marine litter to every kg of plankton.

Just one percent of the world’s 3.5 million fishing boats are large industrial vessels, but they trawl 60 percent of all the fish caught on the planet. Industrial fishing has depleted the world’s stock of tuna, cod, swordfish and marlin by as much as 90 percent in the last century.
(20 July 2006)


Oceans and Global Warming

Mae Wan Ho, Institute of Science in Society
Dr. Mae-Wan Ho explains how oceans determine climate and influence climate change. Urgent need to shift away from fossil fuels to renewable options
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The oceans and the atmosphere are tightly linked, and together form the most dynamic component of the earth’s climate system. They bring moisture to coastal areas that may be carried inland by the wind. Typhoons and hurricanes form over the oceans, and as oceans get warmer these will be more frequent.
(21 July 2006)
Includes sections on climate, the carbon cycle and phytoplankton.


Oceans: Carbon Sink or Source?

Mae Wan Ho, Institute of Science in Society
Do oceans remove carbon dioxide from the atmosphere or contribute to it? The answer is crucial for climate change.
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Carbon dioxide in the atmosphere can dissolve in water, and the colder and more turbulent regions of the oceans tend to absorb carbon dioxide, while the warmer and less turbulent regions release it, carbon dioxide being less soluble in warm water than in cold water. In the early 1990s, the oceans were thought to be a net carbon sink [2], with the North Atlantic Ocean accounting for 60 percent of the carbon dioxide absorbed by the world’s oceans, which amounted to about 2 Gt a year [3].

The passive uptake and release of carbon dioxide is not as important, however, as the active uptake of carbon dioxide by the phytoplankton in photosynthesis and its active release in respiration by the whole community of marine organisms, which amount to about 100 Gt a year each way (Oceans and global warming, this series).

Phytoplankton consists of microscopic green algae that grow at prodigious rates in the surface layers of the oceans, feeding an enormous marine food web that has nine times the biomass of the terrestrial food web. A thriving phytoplankton population would tend to remove more carbon dioxide through photosynthesis than is returned through respiration by the entire community (phytoplankton plus zooplankton and other organisms living in the surface layers), and the ocean works as an effective carbon sink. Conversely, if respiration of the community were to exceed photosynthesis, more carbon dioxide would be generated than is fixed, and the ocean becomes a carbon source.

Monitoring how well the ocean’s plankton is doing is therefore very important for predicting climate and climate change.

Scientists at several Spanish universities used data from nine Spanish cruises conducted between 1991-2000 in the subtropical NE Atlantic to calculate gross primary production (photosynthesis) and respiration [4]. They found that two-thirds of the 33 stations investigated had respiration rate greater than photosynthesis. That meant the phytoplankton was not fixing carbon dioxide fast enough, and the oceans, or at least the northeast Atlantic Ocean could be a carbon source instead of a carbon sink.
(25 July 2006)


Shutting Down the Oceans
Act I: Acid Oceans

Mae Wan Ho, Institute of Science in Society
Global warming and acidification are damaging the phytoplankton at the basis of the oceans’ enormous food web, putting the entire biosphere in jeopardy.
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Imagine vast expanses of oceans devoid of life as far and wide as you can project your senses, no whales, no fish, no seabirds and no corals beneath. The warm seawater is thick with floating plastic wastes and slime, and the oppressive heavy air putrid with death and decay.

That’s not a scene from a science-fiction film, but a likely future scenario unless we take appropriate action now: stop polluting and exploiting the oceans and shift comprehensively to renewable energy options to drastically reduce carbon emissions (Which Energy?).

Increase in carbon dioxide concentration in the atmosphere and global warming are threatening the oceans’ phytoplankton that supports all marine life from zooplankton to whales. Phytoplankton is also the fastest assimilator of carbon, clearing carbon dioxide from the atmosphere to prevent it building up as a greenhouse gas that warms the earth.

When phytoplankton is in jeopardy, all life is in jeopardy, on land and at sea...

Oceans take up carbon dioxide passively by dissolving it in the water of the surface layers, and as carbon dioxide increases in the atmosphere, so too does the concentration of carbon dioxide in the water. This makes the surface water more acidic and interferes with calcification in organisms that make their shells or external skeletons from calcium carbonate.
(25 July 2006)


Shutting Down the Oceans
Act II: Abrupt Plankton Shifts

Mae Wan Ho, Institute of Science in Society
Abrupt changes in the plankton populations in the northeast Atlantic within the past decades that may have radically disrupted the food web, including commercial fisheries.
(26 July 2006)
Facinating if scary article. -AF


Shutting Down the Oceans
Act III: Global Warming and Plankton; Snuffing Out the Green Fuse

Mae Wan Ho, Institute of Science in Society
The oceans’ plankton is about to give us the final curtain call in the greatest tragedy the human species has ever enacted unless we make determined efforts to stop burning fossil fuels right now. Numerous options for sustainable and renewable energies exist (Which Energy?) that will save our oceans and our planet.
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Phytoplankton fixes carbon dioxide in photosynthesis to support its own growth and the growth of the marine food web. Some of the carbon fixed in plankton biomass end up as calcium carbonate sediment on the deep seabed where it remains for thousands of years, but most of the carbon that does not contribute to growth and development is turned back into carbon dioxide by respiration of the entire plankton community. The balance between photosynthesis (primary production) and community respiration therefore determines whether the oceans are a carbon sink or a carbon source.

A team of scientists led by Angel López-Urrutia of the Spanish Institute of Oceanography in Gijón showed that the balance between production and respiration is profoundly affected by temperature, and that while the rates of photosynthesis and respiration both go up with temperature, respiration goes up faster, eventually outstripping photosynthesis [1]. This turns the oceans from a carbon sink to a carbon source.

In fact, vast areas of the North East Atlantic have already become a carbon source, with respiration of the plankton community almost 150 percent of photosynthesis.

The increase in carbon dioxide released to the atmosphere would unleash a positive feedback to aggravate global warming, leading to further deterioration of phytoplankton production, and even more carbon dioxide released in respiration and decomposition.

López-Urrutia and colleagues have based their prediction on the metabolic theory of ecology due to ecologist James Brown and his colleagues at the University of New Mexico Albuquerque in the United States.
(27 July 2006)
Mae-Wan mentions a metabolic rate to body weight formula, a formula which has also been employed by Overshoot author Wiliam Catton to formulate that, considering all the energy U.S. citizens use (not just that which we actually eat), the average person has the metabolic equivalent of a 41 ton dinosaur (PDF)!
-AF


Undersea gas could speed global warming - study

Timothy Gardner, Reuters
If the world continues to get warmer, vast amounts of methane gas trapped in ice under the sea could belch up and worsen climate change, according to a study.

"We may have less time than we think to do something (about the prospect of global warming)," Dr. Ira Leifer, a marine scientist at University of California Santa Barbara, said in an interview.

Leifer is the main author of a study that looks at how "peak blowouts" of melting undersea formations called methane hydrates could release the potent greenhouse gas into the atmosphere. The study was published on Thursday in Global Biogeochemical Cycles, a climate science publication.

The distribution of methane hydrates throughout the world is so vast that energy companies hope one day to tap the resource. The U.S. Department of Energy estimates that such formations could harbor as much as 200,000 trillion cubic feet of natural gas.

Hydrate formations exist under hundreds of meters of water in places like the Gulf of Mexico and closer to the surface in permafrost areas of the Arctic.

Methane, the main component of the fossil fuel natural gas, has two faces. When burned it releases less carbon dioxide, the main greenhouse gas that scientists believe are warming the earth, than any other fossil fuel.

But if it escapes to the atmosphere without being burned, it can trap heat rapidly because it is a greenhouse gas at least 20 times stronger than carbon dioxide.
(20 July 2006)


Warmer waters disrupt Pacific food chain

MARCUS WOHLSEN (AP), New Mexican
On these craggy, remote islands west of San Francisco, the largest seabird colony in the contiguous United States throbs with life. Seagulls swarm so thick that visitors must yell to be heard above their cries. Pelicans glide.

But the steep decline of one bird species for the second straight year has rekindled scientists' fears that global warming could be undermining the coastal food supply, threatening not just the Farallones but entire marine ecosystems.
(24 July 2006)

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