Eastern US/Canada seaboard: be warned. Our winters will get much more severe, & perhaps longer, as climate change keeps worsening. It's due to the Gulf Stream keeps slowing down due to warmer arctic air is mixing with the warmer Atlantic air, slowing the Gulf Stream. This slow Gulf Stream then keeps the cold weather system over Eastern seaboard lingering around for much longer than it used to.
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The Gulf Stream, the ocean current that brings mild weather to northern Europe & 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 & cold water around the Atlantic ocean has slowed by 15-20% 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 100 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 100 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.
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 & sinking of water in different regions of the Atlantic.
Warm water from the equator is driven north towards the Arctic where it cools, increases in salinity & 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 & 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 & feeds the Gulf Stream.
The influx of warm water from the equator, which travels up through the Gulf of Mexico, past Maine & then up the west side of Britain & 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 & the west coast of Norway largely snow & 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.
They estimate that 8,000 cubic kilometres of fresh melt water have flowed into the northern Atlantic from Greenland's icesheets between 1900 & 1970.
They say between 1970 & 2000 an additional 13,000 cubic kilometres of fresh water has poured into the Atlantic from Greenland.
This fresh water is less dense than the salty water of the ocean & 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 & so become more dense. Adding fresh water dilutes this effect.
Using recent sea surface & atmospheric temperature data, along with data from ice-cores, tree rings & 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.
Professor Rahmstorf said: 'If the slowdown of the Atlantic overturning continues, the impacts might be substantial.
'Disturbing the circulation will likely have a negative effect on the ocean ecosystem, & thereby fisheries & the associated livelihoods of many people in coastal areas.
'A slowdown also adds to the regional sea-level rise affecting cities like New York & Boston.
'Finally, temperature changes in that region can also influence weather systems on both sides of the Atlantic, in North America as well as Europe.'
Professor Jason Box, from the Geological Survey of Denmark & Greenland, said it appeared man-made climate change was responsible for the slow down of the Gulf Stream & 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 – & this effect might increase if temperatures are allowed to rise further.'
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The Gulf Stream, the ocean current that brings mild weather to northern Europe & 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 & cold water around the Atlantic ocean has slowed by 15-20% 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 100 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 100 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.
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 & sinking of water in different regions of the Atlantic.
Warm water from the equator is driven north towards the Arctic where it cools, increases in salinity & 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 & 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 & feeds the Gulf Stream.
The influx of warm water from the equator, which travels up through the Gulf of Mexico, past Maine & then up the west side of Britain & 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 & the west coast of Norway largely snow & 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.
They estimate that 8,000 cubic kilometres of fresh melt water have flowed into the northern Atlantic from Greenland's icesheets between 1900 & 1970.
They say between 1970 & 2000 an additional 13,000 cubic kilometres of fresh water has poured into the Atlantic from Greenland.
This fresh water is less dense than the salty water of the ocean & 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 & so become more dense. Adding fresh water dilutes this effect.
Using recent sea surface & atmospheric temperature data, along with data from ice-cores, tree rings & 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.
Professor Rahmstorf said: 'If the slowdown of the Atlantic overturning continues, the impacts might be substantial.
'Disturbing the circulation will likely have a negative effect on the ocean ecosystem, & thereby fisheries & the associated livelihoods of many people in coastal areas.
'A slowdown also adds to the regional sea-level rise affecting cities like New York & Boston.
'Finally, temperature changes in that region can also influence weather systems on both sides of the Atlantic, in North America as well as Europe.'
Professor Jason Box, from the Geological Survey of Denmark & Greenland, said it appeared man-made climate change was responsible for the slow down of the Gulf Stream & 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 – & this effect might increase if temperatures are allowed to rise further.'
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