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News -01-14-06 Ocean Currents Already Changing (Scientific American) "A paper in this week's issue of Nature reveals that the Gulf Stream current system--a band of water that brings tropical warmth to the North Atlantic, keeping Europe from being as cold as it should be--circulates 30 percent less water than it did in the past." 12-05 -01-28-06 Warming Debate Shifts to "Tipping Point" (MSNBC News) "Now that most scientists agree human activity is causing Earth to warm, the central debate has shifted to whether climate change is progressing so rapidly that, within decades, humans may be helpless to slow or reverse the trend." "There are three specific events that these scientists describe as especially worrisome and potentially imminent, although the time frames are a matter of dispute: widespread coral bleaching that could damage the world's fisheries within three decades; dramatic sea level rise by the end of the century that would take tens of thousands of years to reverse; and, within 200 years, a shutdown of the [Atlantic thermohaline] ocean current that moderates temperatures in northern Europe." 01-06 -02-16-06 Melting Glaciers Could Produce "Runaway Effects" (ABC News) "In only five years, the amount of freshwater the melting glaciers have dumped into the Atlantic has nearly doubled, which has caused many scientists to conclude that current projections of how fast sea levels will rise have been too low." "Scientists also worry about the effect all this fresh-melt water will have on the Atlantic's Gulf Stream 'conveyor belt' currents. These currents have long kept the northeastern United States, Britain and northwestern Europe relatively warm for their northern latitudes by transporting heat up from the tropics. Too much freshwater slows these currents, said scientists." "A few weeks ago, scientists announced a surprising discovery — currents have slowed by 30 percent in recent years." "This is the latest confirmation that global warming is now accelerating and involving interconnected 'positive feedback' effects in which the warming in different earth systems reinforces overall warming, and it is all now happening faster than scientists recently thought possible, according to the report." 02-06 -12-20-05 Ocean Currents Already Changing (Scientific American) "A paper in this week's issue of Nature reveals that the Gulf Stream current system--a band of water that brings tropical warmth to the North Atlantic, keeping Europe from being as cold as it should be--circulates 30 percent less water than it did in the past." 12-05 Hydrothermic Activity Beneath the Arctic Ocean (Max Planck Society) "The scientists had expected that the Gakkel ridge would exhibit 'anemic' magmatism. Instead, surprisingly strong magmatic activity in the West and the East of the ridge and one of the strongest hydrothermal activities ever seen at mid-ocean ridges were found. These results require a fundamental rethinking of the mechanisms of seafloor generation at midocean ridges" 12-05 Papers -Editorial: Our Threatened Oceans (Awesome Library) "We have reason for great concern that our oceans are going through a rapid change that may create severe problems for ourselves and disaster for our children and grandchildren. Here are some of the problems...." 01-06 Atlantic Ocean Heat Conveyor Currents (CLIVAR.org) Explains how heat is moved by the currents to moderate the temperatures in Europe. "The oceanic heat transport in the Atlantic Ocean has an obvious and well-known impact on climate. Most of the heat transport in this basin is a consequence of the warm-to-cold water conversion associated with the thermohaline circulation. Fig. 7.1 shows the main northward flowing warm water routes and the cold deep southward return flows that form the North Atlantic thermohaline circulation." 01-06 Ocean Currents and Climate (Stott) Provides graphics and explanations of ocean currents globally, as well as in the ancient past. 3-01 Oceanic Conveyor (Woods Hole Oceanic Institute) "Evidence for abrupt climate change is readily apparent in ice cores taken from Greenland and Antarctica. One sees clear indications of long-term changes discussed above, with CO² and proxy temperature changes associated with the last ice age and its transition into our present interglacial period of warmth. But, in addition, there is a strong chaotic variation of properties with a quasi-period of around 1500 years. We say chaotic because these millennial shifts look like anything but regular oscillations. Rather, they look like rapid, decade-long transitions between cold and warm climates followed by long interludes in one of the two states." Includes an animation showing the global oceanic conveyor of warm and cool currents. 01-06 Oceanic Conveyor (Woods Hole Oceanic Institute) "Evidence for abrupt climate change is readily apparent in ice cores taken from Greenland and Antarctica. One sees clear indications of long-term changes discussed above, with CO² and proxy temperature changes associated with the last ice age and its transition into our present interglacial period of warmth. But, in addition, there is a strong chaotic variation of properties with a quasi-period of around 1500 years. We say chaotic because these millennial shifts look like anything but regular oscillations. Rather, they look like rapid, decade-long transitions between cold and warm climates followed by long interludes in one of the two states." Includes an animation showing the global oceanic conveyor of warm and cool currents. 01-06 Thermohaline Conveyor Currents (Climatic Research Unit) "There are three main processes that make the oceans circulate: tidal forces, wind stress, and density differences. The density of sea water is controlled by its temperature (thermo) and its salinity (haline), and the circulation driven by density differences is thus called the thermohaline circulation. The animation and list below describes the key features of the global-scale thermohaline circulation." 01-06 Thermohaline Conveyor Currents (GRID-Arendal) "The global conveyor belt thermohaline circulation is driven primarily by the formation and sinking of deep water (from around 1500m to the Antarctic bottom water overlying the bottom of the ocean) in the Norwegian Sea. This circulation is thought to be responsible for the large flow of upper ocean water from the tropical Pacific to the Indian Ocean through the Indonesian Archipelogo. The two counteracting forcings operating in the North Atlantic control the conveyor belt circulation: (1) the thermal forcing (high-latitude cooling and the low-latitude heating) which drives a polar southward flow; and (2) haline forcing (net high-latitude freshwater gain and low-latitude evaporation) which moves in the opposite direction. In today's Atlantic the thermal forcing dominates, hence, the flow of upper current from south to north." Provides a global chart of the flow of the currents. "When the strength of the haline forcing increases due to excess precipitation, runoff, or ice melt the conveyor belt will weaken or even shut down." 01-06 Thermohaline Conveyor Currents (NATSCI) "The major water masses in the deep ocean are differentiated by their temperature and salinity. These properties determine their relative densities, which in turn drive deep thermohaline circulation of the oceans." Provides a side or "cross-sectional" view of the Atlantic Ocean and how the currents flow downward. 01-06 Thermohaline Conveyor Currents (Wikipedia.org) "The thermohaline circulation is a term for the global density-driven circulation of the oceans. Derivation is from thermo- for heat and -haline for salt, which together determine the density of sea water." "The thermohaline circulation is sometimes called the ocean conveyor belt, the global conveyor belt, or, most commonly nowadays, the meridional overturning circulation (often abbreviated as MOC)." "The vertical exchange of dense, sinking water with lighter water below it is known as overturning. Hence, a recent and popular name for the thermohaline circulation, emphasizing the vertical nature and pole-to-pole character of this kind of ocean circulation, is the meridional overturning circulation." 01-06 Thermohaline Conveyor Currents Fact-Sheet (Appenzeller) "The thermohaline circulation is a global ocean circulation. It is driven by differences in the density of the sea water which is controlled by temperature (thermal) and salinity (haline). In the North Atlantic it transports warm and salty water to the North. There the water is cooled and sinks into the deep ocean." "There is evidence for rapid climate change events lasting 1000 years or so during the last glacial." The idea is that the melt water of dying continental ice masses was released into the North Atlantic where it substantially reduced the density of the ocean surface water and thereby shut down the deep water formation." 01-06

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