Aligned Planets
14-11-2004, 02:22
To: Chmhayak Vosneh, President, Federation of Aligned Planets
From: Federation Oceanographic Research Team, Heller Station, Greenland
Concerning: Current Climatic Conditions - URGENT
It has long been considered probable that the illustrious Ice Ages came and went on time scales measured in tens of thousands of years, and less momentous variations – such as the Holocene Maximum or the Little Ice Age--over the span of several centuries. Current research and more recent palaeodata have uncovered an entirely different face of the climate system, called "abrupt transitions," in which major disruptions to some components of the climate are accomplished on time scales of decades or less.
Initially proposed, and later ratified, was the revolutionary notion that the large-scale circulation in the North Atlantic could persist in one of two patterns, or states, both of which were quite stable, with the possibility of abrupt switching between the two. In the first, the warm Gulf Stream that flows along the eastern coast of the U.S. continues northward, reaching beyond the British Isles to the Norwegian Sea, restructuring the climate of northwest Europe.
In the other mode, the northward extension of the Gulf Stream is destabilized by a lessening in the salinity of surface waters in high latitude regions of the North Atlantic. With less salt, seawater is not as dense, and is less able to sink during normal wintertime cooling. Confining the capability of the North Atlantic to circulate water downward limits the amount flowing in from the warm Gulf Stream. The result of this "short-circuit" in ocean circulation is a much cooler climate for all who live downstream, including Northern Europe.
The evidence from the palaeoclimate record is how quickly the substitution between warm and cold states can be accomplished. Support from ice-age portions of recent Greenland ice cores suggests that changes of this sort may have taken place in the past in the span of five to ten years. These abrupt transitions are most likely linked to an increase in the release of icebergs from continental glaciers, which on melting contribute large volumes of freshwater into the ocean, systematically reducing the local salinity.
Whatever the cause, it is now known that in at least the North Atlantic the climate system can change very rapidly. Might ocean circulation change as rapidly in the future, perhaps as a consequence of other significant changes in the system? The answer is "maybe." There are no permanent ice sheets today on the North American continent, as was the case in the past, but melting of Arctic sea ice or the extensive Greenland ice cap could well influence ocean salinities. Increased precipitation over the North Atlantic, induced by warmer temperatures, could also reduce the saltiness of seawater, short-circuiting the ocean circulation in a manner similar to what occurred during the ice ages.
Ocean currents and temperature patterns in the Pacific Ocean also play an important role in regulating our climate. Recent research has revealed an oscillation in the Pacific Ocean that can affect climate across the United States. Positive phases enhance the occurrence of El Nino events and negative phases increase the occurrence of La Nina events. These oceanic and atmospheric patterns can have a large impact on marine and terrestrial ecosystems.
The equatorial sun warms the ocean surface and enhances evaporation in the tropics. This leaves the tropical ocean saltier. The Gulf Stream, a limb of the Ocean Conveyor, carries an enormous volume of heat-laden, salty water up the East Coast of the United States, and then northeast toward Europe. For a variety of reasons, North Atlantic waters are relatively salty compared with other parts of the world ocean. Salty water is denser than fresh water. Cold water is denser than warm water. When the warm, salty waters of the North Atlantic release heat to the atmosphere, they become colder and begin to sink.
In the seas that ring the northern fringe of the Atlantic—the Labrador, Irminger, and Greenland Seas—the ocean releases large amounts of heat to the atmosphere and then a great volume of cold, salty water sinks to the abyss. This water flows slowly at great depths into the South Atlantic and eventually throughout the world’s oceans. Thus, the North Atlantic is the source of the deep limb of the Ocean Conveyor. The plunge of this great mass of cold, salty water propels the global ocean’s conveyor-like circulation system. It also helps draw warm, salty tropical surface waters northward to replace the sinking waters. This process is called “thermohaline circulation,” from the Greek words “thermos” (heat) and “halos” (salt).
If cold, salty North Atlantic waters did not sink, a primary force driving global ocean circulation could slacken and cease. Existing currents could weaken or be redirected. The resulting reorganization of the ocean’s circulation would reconfigure Earth’s climate patterns.
An influx of fresh water into the North Atlantic’s surface could create a lid of more buoyant fresh water, lying atop denser, saltier water. This fresh water would effectively cap and insulate the surface of the North Atlantic, curtailing the ocean’s transfer of heat to the atmosphere. An influx of fresh water would also dilute the North Atlantic’s salinity. At a critical but unknown threshold, when North Atlantic waters are no longer sufficiently salty and dense, they may stop sinking. An important force driving the Conveyor could quickly diminish, with climate impacts resulting within a decade.
In an important paper published recently, oceanographers monitoring and analysing conditions in the North Atlantic concluded that the North Atlantic has been freshening dramatically—continuously for the past 40 years but especially in the past decade. The new data show that since the mid-1960s, the subpolar seas feeding the North Atlantic have steadily and noticeably become less salty to depths of 1,000 to 4,000 meters. This is the largest and most dramatic oceanic change ever measured in the era of modern instruments.
At present the influx of fresher water has been distributed throughout the water column. But at some point, fresh water may begin to pile up at the surface of the North Atlantic. When that occurs, the Conveyor will slow down and cease operating, triggering a new era in the current glacial epoch.
<This report was received on the Desk of the President of the Federation of Aligned Planets 4 years ago.>
From: Federation Oceanographic Research Team, Heller Station, Greenland
Concerning: Current Climatic Conditions - URGENT
It has long been considered probable that the illustrious Ice Ages came and went on time scales measured in tens of thousands of years, and less momentous variations – such as the Holocene Maximum or the Little Ice Age--over the span of several centuries. Current research and more recent palaeodata have uncovered an entirely different face of the climate system, called "abrupt transitions," in which major disruptions to some components of the climate are accomplished on time scales of decades or less.
Initially proposed, and later ratified, was the revolutionary notion that the large-scale circulation in the North Atlantic could persist in one of two patterns, or states, both of which were quite stable, with the possibility of abrupt switching between the two. In the first, the warm Gulf Stream that flows along the eastern coast of the U.S. continues northward, reaching beyond the British Isles to the Norwegian Sea, restructuring the climate of northwest Europe.
In the other mode, the northward extension of the Gulf Stream is destabilized by a lessening in the salinity of surface waters in high latitude regions of the North Atlantic. With less salt, seawater is not as dense, and is less able to sink during normal wintertime cooling. Confining the capability of the North Atlantic to circulate water downward limits the amount flowing in from the warm Gulf Stream. The result of this "short-circuit" in ocean circulation is a much cooler climate for all who live downstream, including Northern Europe.
The evidence from the palaeoclimate record is how quickly the substitution between warm and cold states can be accomplished. Support from ice-age portions of recent Greenland ice cores suggests that changes of this sort may have taken place in the past in the span of five to ten years. These abrupt transitions are most likely linked to an increase in the release of icebergs from continental glaciers, which on melting contribute large volumes of freshwater into the ocean, systematically reducing the local salinity.
Whatever the cause, it is now known that in at least the North Atlantic the climate system can change very rapidly. Might ocean circulation change as rapidly in the future, perhaps as a consequence of other significant changes in the system? The answer is "maybe." There are no permanent ice sheets today on the North American continent, as was the case in the past, but melting of Arctic sea ice or the extensive Greenland ice cap could well influence ocean salinities. Increased precipitation over the North Atlantic, induced by warmer temperatures, could also reduce the saltiness of seawater, short-circuiting the ocean circulation in a manner similar to what occurred during the ice ages.
Ocean currents and temperature patterns in the Pacific Ocean also play an important role in regulating our climate. Recent research has revealed an oscillation in the Pacific Ocean that can affect climate across the United States. Positive phases enhance the occurrence of El Nino events and negative phases increase the occurrence of La Nina events. These oceanic and atmospheric patterns can have a large impact on marine and terrestrial ecosystems.
The equatorial sun warms the ocean surface and enhances evaporation in the tropics. This leaves the tropical ocean saltier. The Gulf Stream, a limb of the Ocean Conveyor, carries an enormous volume of heat-laden, salty water up the East Coast of the United States, and then northeast toward Europe. For a variety of reasons, North Atlantic waters are relatively salty compared with other parts of the world ocean. Salty water is denser than fresh water. Cold water is denser than warm water. When the warm, salty waters of the North Atlantic release heat to the atmosphere, they become colder and begin to sink.
In the seas that ring the northern fringe of the Atlantic—the Labrador, Irminger, and Greenland Seas—the ocean releases large amounts of heat to the atmosphere and then a great volume of cold, salty water sinks to the abyss. This water flows slowly at great depths into the South Atlantic and eventually throughout the world’s oceans. Thus, the North Atlantic is the source of the deep limb of the Ocean Conveyor. The plunge of this great mass of cold, salty water propels the global ocean’s conveyor-like circulation system. It also helps draw warm, salty tropical surface waters northward to replace the sinking waters. This process is called “thermohaline circulation,” from the Greek words “thermos” (heat) and “halos” (salt).
If cold, salty North Atlantic waters did not sink, a primary force driving global ocean circulation could slacken and cease. Existing currents could weaken or be redirected. The resulting reorganization of the ocean’s circulation would reconfigure Earth’s climate patterns.
An influx of fresh water into the North Atlantic’s surface could create a lid of more buoyant fresh water, lying atop denser, saltier water. This fresh water would effectively cap and insulate the surface of the North Atlantic, curtailing the ocean’s transfer of heat to the atmosphere. An influx of fresh water would also dilute the North Atlantic’s salinity. At a critical but unknown threshold, when North Atlantic waters are no longer sufficiently salty and dense, they may stop sinking. An important force driving the Conveyor could quickly diminish, with climate impacts resulting within a decade.
In an important paper published recently, oceanographers monitoring and analysing conditions in the North Atlantic concluded that the North Atlantic has been freshening dramatically—continuously for the past 40 years but especially in the past decade. The new data show that since the mid-1960s, the subpolar seas feeding the North Atlantic have steadily and noticeably become less salty to depths of 1,000 to 4,000 meters. This is the largest and most dramatic oceanic change ever measured in the era of modern instruments.
At present the influx of fresher water has been distributed throughout the water column. But at some point, fresh water may begin to pile up at the surface of the North Atlantic. When that occurs, the Conveyor will slow down and cease operating, triggering a new era in the current glacial epoch.
<This report was received on the Desk of the President of the Federation of Aligned Planets 4 years ago.>