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Politics : Sioux Nation -- Ignore unavailable to you. Want to Upgrade?

To: Triffin who wrote (91163)	12/7/2006 12:37:17 PM
From: SiouxPal	Read Replies (2) \| Respond to of 360932

Climate Change is Killing the Oceans' Microscopic 'Lungs' by Steve Connor Global warming has begun to change the way microscopic plant life in the oceans absorbs carbon dioxide from the atmosphere - a trend that could lead to a dramatic increase in the heating power of the greenhouse effect. This NASA Aqua satellite image released in 2003 shows clouds of phytoplankton thriving in the cold, nutrient-rich waters off of Greenland's eastern coast. A new study of the oceans suggests that phytoplankton -- the vital first link in the food chain of the seas -- will be hugely affected by global warming. (AFP/NASA-HO/File) Satellite data gathered over the past 10 years has shown for the first time that the growth of marine phytoplankton - the basis of the entire ocean food chain - is being adversely affected by rising sea temperatures. Scientists have found that as the oceans become warmer, they are less able to support the phytoplankton that have been an important influence on moderating climate change. The fear is that as sea temperatures continue to rise as a result of global warming, the loss of phytoplankton will lead to a positive-feedback cycle, where increases in carbon dioxide concentrations in the atmosphere leads to warmer oceans, and warmer oceans lead to increasing carbon dioxide concentrations. A team of American scientists used a Nasa satellite to study global concentrations of phytoplankton over the past two decades to see how ocean productivity - as measured by the density of chlorophyll, the pigment of photosynthesis - changes with sea temperatures. The result was a clear link between warmer oceans and decreases in ocean productivity, said Michael Behrenfeld, professor of botany at Oregon State University and lead author of the study published in the journal Nature. "Rising levels of carbon dioxide in the atmosphere are a key part of global warming. This study shows that as the climate warms, phytoplankton production goes down, but this also means that carbon dioxide uptake by the ocean plants will decrease," Professor Behrenfeld said. "That would allow carbon dioxide to accumulate more rapidly in the atmosphere, making the problem worse." As average global sea temperatures increase, the growing season in some parts of the ocean at high latitudes is extended. This has the effect of boosting phytoplankton growth in these regions. But for most other areas of the world, the opposite occurs, because phytoplankton are starved of nutrients when sea temperatures rise too high. "There is regional variability. But on a global basis,increased temperatures causes decreased phytoplankton production," Professor Behrenfeld said. Phytoplankton needs nutrients and sunlight to grow and in warmer, tropical oceans, the levels of nutrients become the limiting factor because there are few "upwelling" currents from the sea bed to bring nitrogen, phosphorus and iron to the surface layers. In tropical seas, the water forms layers, with warm water sitting on top of cooler water. When seawater becomes layered or stratified in this way, nutrients are prevented from rising to the surface where the phytoplankton live. This is why cooler oceans at higher latitudes in the north and south are more productive than tropical oceans near the equator. Global warming is having the effect of extending the range of nutrient-poor regions of the ocean to include areas that were richer in phytoplankton "blooms" on which all other marine life depends. Despite their small size, phytoplankton account for about half of the photosynthesis carried out by all plants on Earth. And phytoplankton have a high turnover because they are quickly eaten by small marine animals - making them even more vulnerable to climate change. "This fast turnover and the fact that phytoplankton are limited to a thin veneer of the ocean surface, where there is enough sunlight to sustain photosynthesis, makes them very responsive to climate change," Professor Behrenfeld said. "This was why we could relate productivity changes to climate variability in only a 10-year record. Such connections would be much harder to detect from space for terrestrial plant biomass." © 2006 Independent News and Media Limited Published on Thursday, December 7, 2006 by the Independent / UK

To: Triffin who wrote (91163)	12/7/2006 1:07:12 PM
From: Wharf Rat	Read Replies (3) \| Respond to of 360932

Oh, Lord, buy The Weathermakers. I'll tell you 2 B4 I go to bed. It takes about 2 Sverdrups of fresh water to slow down or stop the Gulf Stream, Sverdrup is a flow of 1.3 million cubic yards/sec. 13 K years ago, an ice dam broke and shifted some North American river drainage from the Miss. to the St Lawrence. Enuf to dilute the saline/ temperature pump driving the Gulf Stream, and stop it. Which normally keeps London, as far north as Anchorage, temperate. Called the Younger Dryas. 8K years ago, an ice dam broke going into Hudson Bay. Similar results.

To: Triffin who wrote (91163)	12/8/2006 1:04:21 PM
From: Wharf Rat	Read Replies (2) \| Respond to of 360932

Opposite example...gets colder and colder, too. Twice, 710 M and 600 M years ago, we crossed a threshold that almost exterminated life, freeing the planet right to the equator. (CO2 levels were low at those points). Has to do with albedo; sun reflection. Snow reflects up to 90% of the heat. Black absorbs it. Once a certain proportion of the earth is covered with snow and ice, enuf sunlight is reflected to cause runaway cooling. Happens when ice sheets reach about 30 degrees of latitude.