Thermohaline circulation
Thermohaline circulation (
THC) is a part of the large-scale
ocean circulation that is driven by global
density gradients created by surface heat and freshwater
fluxes.
[1][2] The adjective thermohaline derives from
thermo- referring to
temperature and
-haline referring to
salt content, factors which together determine the
density of sea water.
Wind-driven surface currents (such as the
Gulf Stream) travel polewards from the equatorial
Atlantic Ocean, cooling en route, and eventually sinking at high
latitudes (forming
North Atlantic Deep Water). This dense water then flows into the
ocean basins. While the bulk of it
upwells in the
Southern Ocean, the oldest waters (with a transit time of around 1000 years)
[3] upwell in the North Pacific.
[4] Extensive mixing therefore takes place between the ocean basins, reducing differences between them and making the Earth's oceans a global system. On their journey, the water masses transport both energy (in the form of heat) and matter (solids, dissolved substances and gases) around the globe. As such, the state of the circulation has a large impact on the
climate of the Earth.
Effects on global climate
The thermohaline circulation plays an important role in supplying heat to the polar regions, and thus in regulating the amount of sea ice in these regions, although poleward heat transport outside the tropics is
considerably larger in the atmosphere than in the ocean.
[15] Changes in the thermohaline circulation are thought to have significant impacts on the Earth's
radiation budget. Insofar as the thermohaline circulation governs the rate at which deep waters are exposed to the surface, it may also
play an important role in the concentration of carbon dioxide in the atmosphere. While it is often stated that the thermohaline circulation is the primary reason that Western Europe is so temperate, it has been suggested that this is largely incorrect, and that Europe is warm mostly because it lies downwind of an ocean basin, and because of the effect of
atmospheric waves bringing warm air north from the
subtropics.
[16] However, the underlying assumptions of this particular analysis have likewise been challenged.
[17]
Large influxes of low-density meltwater from
Lake Agassiz and deglaciation in
North America are thought to have led to a shifting of deep water formation and subsidence in the extreme North Atlantic and caused the climate period in Europe known as the
Younger Dryas.
[18]
The
Younger Dryas (
YD) interval (
stadial), also referred to as the
Big Freeze, was an abrupt return to
glacial-like conditions during the transition to a warmer,
interglacial climate that occurred at the end of the Late Glacial interval. The Younger Dryas is the youngest, longest, and coldest of three stadials that
resulted from typically abrupt climatic changes that took place over the last 16,000 calendar years.
In 2005, British researchers noticed that the net flow of the northern Gulf Stream had decreased by about 30% since 1957. Coincidentally, scientists at Woods Hole had been measuring the freshening of the North Atlantic as Earth becomes warmer. Their findings suggested that precipitation increases in the high northern latitudes, and polar ice melts as a consequence. By flooding the northern seas with lots of extra fresh water, global warming could, in theory, divert the Gulf Stream waters that usually flow northward, past the British Isles and Norway, and cause them to instead circulate toward the equator. If this were to happen, Europe's climate would be seriously impacted.
[19][20][21]
https://en.wikipedia.org/wiki/Thermohaline_circulation
Well it looks like Europe should brace itself for a deep freeze thanks to global warming slowing the thermohaline circulation.
Europe and US breaking all snow and cold records this winter
Friday, 6 February 2015
Europe now joins US in breaking snow and cold records this winter
Severe winter weather has been causing chaos for many across parts of Europe.
Some parts of Sweden had the most snow in the last 50 years, Italy and Spain are among the countries that have seen arctic weather over the last few days.
Spanish police say they have rescued at least 220 people, including 100 from Britain, who were stuck in their cars in heavy snow in northern Spain.
Some had been stranded for up to 17 hours overnight, with temperatures falling as low as -15C (5F).
Many were going to Spain to escape the "cold". Spain hasn't seen so much snow for years.
In the beginning of January up to 15,000 motorists were stranded in heavy snow in the French Alps. Travellers reported gridlock on the roads and miles of tailbacks, forcing some to abandon their cars and seek emergency shelter.
Just today homes were buried as severe snow blasted Austria:
Austria is the latest country to feel the force of severe weather sweeping across Europe, in some parts whole houses have been buried under the snow. The Austrian Army have been brought in to cut down tree tops before they snap from the weight of the snow, they are also using helicopters to create downstream to remove snow from the trees to prevent them from snapping and blocking roads.
The outlook for Europe looks bleak, with more snow and heavy winds to come.
The US has fared no better this winter, just last week areas of the north-east US shut down as heavy snow fell across the entire region. More than 5000 flights were cancelled and over 2ft (60cm) of snow fell in some areas.
Winds of over 70 mph (112km/h) made the problem even worse. The national weather service has described the storm as "
historic".
In January THE POLAR VORTEX RETURNED...'Dangerous' arctic air roared into U.S.
The blasts of cold air sent temperatures 10-35 degrees below average for early January, In November there were more than 350 record lows and record cool highs set, covering 42 states, the US.
In January Winter Storm Gorgon's arrival in the Midwest dropped around 2,000 square miles of snow.
Last month parts of the US were colder than Mars!
And the harsh winter, we could be looking at cold temperatures humans shouldn't have to bear and probably never have before!
http://www.thebigwobble.org/2015/02/europe-and-us-breaking-all-snow-and.html
