By JR on Saturday, March 28, 2015
More stupid speculation and bad data from some arch-Warmists
The data behind the claim below is totally corrupt, almost hilariously so, (See here) but even if it were immaculate the inferences drawn below from it would still be very questionable
The North Atlantic meridional overturning circulation is not well understood and attributing a change in it to global warming is pure speculation. Rahmstorf is an oceanographer so he should be particularly ashamed at lending his name to this. But, then again, he claims that observed average temperature differences of a few HUNDREDTHS of a degree mean something, even though they are not even statistically significant.
And attributing changes in such a vast body of water to a temperature rise of less than one degree Celsius is on the face of it improbable anyhow
The Gulf Stream, the ocean current that brings mild weather to northern Europe and balmy conditions to the south east of the US, is slowing at its fastest rate in 1,000 years.
New research has revealed that the enormous currents that circulate warm and cold water around the Atlantic ocean has slowed by 15-20 per cent over the past century.
Scientists say that the increasing flow of fresh water from melting Greenland ice sheets may be driving the slowdown.
Professor Stefan Rahmstorf, an oceans physicist at the Potsdam Institute for Climate Impact Research, said: 'It is conspicuous that one specific area in the North Atlantic has been cooling in the past hundred years while the rest of the world heats up.
'Now we have detected strong evidence that the global conveyor has indeed been weakening in the past hundred years, particularly since 1970.
The findings suggest that as global temperatures rise due to climate change, areas that are warmed by the Gulf Stream could see temperatures fall, particularly in the winter. [Warming causes cooling, once again]
The Gulf Stream is a powerful current that forms part of the North Atlantic meridional overturning circulation.
This is a system of currents that are driven by the rising and sinking of water in different regions of the Atlantic.
Warm water from the equator is driven north towards the Artic where it cools, increases in salinity and sinks to the ocean depths.
This drives deep sea currents that pump water back to the equator, where it is warmed, rising to the surface and feeding the currents towards the pole.
In the Arctic, cold salty water sinks to the ocean depths, driving deep sea currents down to the equator where warmer water then rises to the surface and feeds the Gulf Stream.
The influx of warm water from the equator, which travels up through the Gulf of Mexico, past Maine and then up the west side of Britain and Norway, helps to warm weather systems in Northern Europe.
It makes winter conditions in much of northern Europe far milder than they normally would be, keeping Britain and the west coast of Norway largely snow and ice free through the winter months.
The researchers, whose study is published in the journal Nature Climate Change, found that the sea in the northern Atlantic is colder than predicted by computer models. [What? Another model failure?]
They estimate that 8,000 cubic kilometres of fresh melt water haver flowed into the northern Atlantic from Greenland's icesheets between 1900 and 1970.
This fresh water is less dense than the salty water of the ocean and tends to float on the surface, disturbing the balance that causes cold water to sink in that region.
Usually freezing sea ice in the arctic causes the salinity of the ocean water to increase and so become more dense. Adding fresh water dilutes this effect.
Using recent sea surface and atmospheric temperature data, along with data from ice-cores, tree rings and sediments, they found that the changes in the ocean currents are unprecedented since the year 900AD.
However, the researchers also found that the cooling above the Northern Atlantic may also help to slightly reduce the effect of warming on the continents due to climate change.
They warn, however, that if the circulation weakens too much it could even break down completely. [How?]
Professor Jason Box, from the Geological Survey of Denmark and Greenland, said it appeared man-made climate change was responsible for the slow down of the Gulf Stream and may worsen as global temperatures increase.
He said: 'The human-caused mass loss of the Greenland ice sheet appears to be slowing down the Atlantic overturning – and this effect might increase if temperatures are allowed to rise further.'