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Posted
  • Location: portsmouth uk
  • Weather Preferences: extremes
  • Location: portsmouth uk

What else can you foresee? :nonono:

attachicon.gifimage.jpg

Well I can see with much colder sst,

that with track of the jet stream plenty of deep low pressure systems spawning from that direction there for keeping a positive nao and ao of coarse this is just a theory.

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Posted
  • Location: Ski Amade / Pongau Region. Somtimes Skipton UK
  • Weather Preferences: Northeasterly Blizzard and sub zero temperatures.
  • Location: Ski Amade / Pongau Region. Somtimes Skipton UK

My teenage years were in the late 60s. Its then I took an interest in all things to do with the weather. I started to subscribe to the Met Office DWR postal service and another magazine called Mariners Log. A lot of observations made in this log during the ( cool ) 6Os referred to the low Atlantic temperatures between Newfoundland across the sub Polar zone towards the British Isles and its subsequent effect on the weather at the time. More a observational rather than analytic theories were published during this era. Stored boxes of these magazines, wish I keep them but got lost in futures transits. Weather observers on land and at sea provided a great insight and knowledge during this time.

All I can report, the 60s, were much cooler summers than I can remember from any other decade in my time. Most of the winters were cold ( ie ) blocked, particularly for Southern and Eastern England. 62/63 of course the holy grail of winters and February 69 produced the best polar low snowfall ever for many.

C

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Posted
  • Location: Yorkshire Puddin' aka Kirkham, Lancashire, England, United Kingdom
  • Weather Preferences: cold winters, cold springs, cold summers and cold autumns
  • Location: Yorkshire Puddin' aka Kirkham, Lancashire, England, United Kingdom


The cold pool seems to have weakened a tad to my eye and one mustn't forget the positive anomalies in the western Atlantic and Davis Strait

Yeah great point there.  I hate to admit it but this looks like a strong signal for a +NAO and +AO to me sadly. :(

 

When you look at the Nino years, SST anomalies for winter and summer, the composite shows negative anomalies in the Atlantic for both seasons.

 

Summer  j7NcUPr.gif  winter  Hf7imvp.gif

 

Those are some very surprising anomalies there.  The Arctic looks very cold here and yet I always remember reading that the Arctic becomes ridiculously warm during El Nino years.  Similarly I remember reading that South East Asia/Australasia usually get heatwaves and fires during El Nino years and yet the SSTs are unusually cool there too in these charts.

 

 

On another note I wonder how the extreme ranges of the CET this century will respond to the Atlantic cooling if it continues and intensifies.

 

Will we be seeing more warm/hot CETs like these or even warmer?:-

-January 2007     7C

-February 2002   7C

-March 2012        8.3C

-April 2011           11.8C

-May 2008           13.4C

-June 2003           16.1C

-July 2003            19.7C

-August 2003       18.3C

-September 2006 16.8C

-October 2001      13.3C

-November 2011  9.6C

-December 2006  6.5C

 

Or will we be finally seeing more cool/cold CETs like these or even cooler?:-

-January 2010            1.4C

-February 2010           2.8C

-March 2013               2.7C

-April 2012                  7.2C

-May 2013                  10.4C

-June 2012                 13.5C

-Julys 2007 and 2011 15.2C

-August 2014              14.9C

-September 2012        13C

-October 2003             9.2C

-November 2010         5.2C

-December 2010         -0.7C

Edited by Goodbye Cold Weather! :(
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Posted
  • Location: Ireland, probably South Tipperary
  • Weather Preferences: Cold, Snow, Windstorms and Thunderstorms
  • Location: Ireland, probably South Tipperary

That cold anomaly is now falling apart on the unisys SST charts

 

tEUHxxx.gif

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Posted
  • Location: Truro, Cornwall
  • Weather Preferences: Winter - Heavy Snow Summer - Hot with Night time Thunderstorms
  • Location: Truro, Cornwall

Seems to be dissipating faster than I thought it could! Interesting. Suspect it will still be average at best by the latter stages of autumn? Can't see it lasting into winter in that state though.

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Posted
  • Location: Hadleigh, Suffolk
  • Weather Preferences: An Alpine climate - snowy winters and sunny summers
  • Location: Hadleigh, Suffolk

The jetstream had moved polewards in line with the expansion of the ITCZ [which now seems to have reversed] during 20th century and there is evidence that the jet has shifted equatorwards, not just become more meridional.  I suppose it will be down to which establishment you take note of BFTV, just like AGW or not.

 

BFTP

 

This extract from the paper 'Drivers of North Atlantic Polar Front Jet Stream' published August 2014 has a snippet that's relevant to your discussion re the 'movement' north/south of the PFJ (with thanks to Nouska for first posting the link to this paper):

 

The change over time of the winter North Atlantic PFJ latitude and speed are shown in Figure 2, together with winter trends in the NAO and EA. Jet latitude has a pole-ward trend up to the start of the 21st century, but there is no significant trend in jet speed (Woollings and Black-burn, 2012). The jet stream latitude can be seen to closely correspond to changes in the NAO (r=0.83, detrended), whereas the jet speed plot bears a closer resemblance to the EA time series (r=0.50, detrended). However, recent years indicate a decrease in the NAO and jet latitude, at least in winter (e.g. Fereday et al., 2012).

 

Fig.2 (top left graph shows latitude) post-20040-0-00836200-1441630936_thumb.j

 

Full paper: http://www.researchgate.net/publication/265017222_Drivers_of_North_Atlantic_Polar_Front_jet_stream_variability

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Posted
  • Location: Near King's Lynn 13.68m ASL
  • Weather Preferences: Hoar Frost, Snow, Misty Autumn mornings
  • Location: Near King's Lynn 13.68m ASL
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Posted
  • Location: Hadleigh, Suffolk
  • Weather Preferences: An Alpine climate - snowy winters and sunny summers
  • Location: Hadleigh, Suffolk

That cold anomaly is now falling apart on the unisys SST charts

 

 

Yes, the decrease in the SST anomaly in August was noteable. However, a look at the SST Anomaly Graph from 1979 to date shows that large increases/decreases are fairly common within the longer term trend. The thick line on the graph (updated 5th Sept 2015) is a running average of the last 37 months and therefore despite the August figure continues a recent downward trend. (Although I note it only gets the SST back to where it was in 1980).

 

post-20040-0-35039600-1441634495_thumb.g

 

Source: National Oceanographic and Atmospheric Administration (NOAA)

 

A closer look at the month-by-month measures (below) shows that last year in Sept the negative anomaly disappeared, before once again turning negative later in the winter. So this August's 'weakening' of the negative anomaly is certainly occurring earlier this year, and (of course) we will have to wait and see if the negative anomaly picks up again later this winter and the overall downward trend in SST continues.

 

(Below, NATL is the North Atlantic measurements).

YR MON    NATL    ANOM    SATL    ANOM    TROP    ANOM  

2014   1   25.94   -0.05   25.53   -0.09   27.64   -0.02

2014   2   25.38   -0.21   26.71    0.14   27.79   -0.07

2014   3   25.28   -0.32   27.17    0.05   28.27   -0.01

2014   4   25.63   -0.30   27.16    0.14   28.77    0.16

2014   5   26.03   -0.34   26.59    0.39   28.88    0.39

2014   6   26.47   -0.31   25.25    0.31   28.40    0.41

2014   7   26.91   -0.32   23.79    0.02   27.70    0.23

2014   8   27.54   -0.23   23.05   -0.03   27.45    0.28

2014   9   28.22    0.07   22.99   -0.04   27.50    0.25

2014  10   28.38    0.28   23.34   -0.04   27.79    0.32

2014  11   27.73    0.11   23.52   -0.45   27.97    0.32

2014  12   26.84    0.02   24.35   -0.37   27.95    0.30

2015   1   26.06    0.07   25.67    0.05   27.87    0.22

2015   2   25.83    0.25   26.69    0.12   28.08    0.22

2015   3   25.43   -0.17   27.15    0.03   28.50    0.22

2015   4   25.62   -0.31   27.26    0.24   28.97    0.36

2015   5   26.00   -0.37   26.64    0.45   29.07    0.58

2015   6   26.38   -0.40   24.94    0.00   28.57    0.58

2015   7   26.91   -0.32   23.63   -0.15   28.13    0.66

2015   8   27.70   -0.07   22.75   -0.34   27.81    0.65

 

Source: National Oceanographic and Atmospheric Administration (NOAA)

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Posted
  • Location: Ireland, probably South Tipperary
  • Weather Preferences: Cold, Snow, Windstorms and Thunderstorms
  • Location: Ireland, probably South Tipperary

Yes, the decrease in the SST anomaly in August was noteable. However, a look at the SST Anomaly Graph from 1979 to date shows that large increases/decreases are fairly common within the longer term trend. The thick line on the graph (updated 5th Sept 2015) is a running average of the last 37 months and therefore despite the August figure continues a recent downward trend. (Although I note it only gets the SST back to where it was in 1980).

 

attachicon.gifNOAA SST-NorthAtlantic GlobalMonthlyTempSince1979 With37monthRunningAverage.gif

 

Source: National Oceanographic and Atmospheric Administration (NOAA)

 

A closer look at the month-by-month measures (below) shows that last year in Sept the negative anomaly disappeared, before once again turning negative later in the winter. So this August's 'weakening' of the negative anomaly is certainly occurring earlier this year, and (of course) we will have to wait and see if the negative anomaly picks up again later this winter and the overall downward trend in SST continues.

 

(Below, NATL is the North Atlantic measurements).

YR MON    NATL    ANOM    SATL    ANOM    TROP    ANOM  

2014   1   25.94   -0.05   25.53   -0.09   27.64   -0.02

2014   2   25.38   -0.21   26.71    0.14   27.79   -0.07

2014   3   25.28   -0.32   27.17    0.05   28.27   -0.01

2014   4   25.63   -0.30   27.16    0.14   28.77    0.16

2014   5   26.03   -0.34   26.59    0.39   28.88    0.39

2014   6   26.47   -0.31   25.25    0.31   28.40    0.41

2014   7   26.91   -0.32   23.79    0.02   27.70    0.23

2014   8   27.54   -0.23   23.05   -0.03   27.45    0.28

2014   9   28.22    0.07   22.99   -0.04   27.50    0.25

2014  10   28.38    0.28   23.34   -0.04   27.79    0.32

2014  11   27.73    0.11   23.52   -0.45   27.97    0.32

2014  12   26.84    0.02   24.35   -0.37   27.95    0.30

2015   1   26.06    0.07   25.67    0.05   27.87    0.22

2015   2   25.83    0.25   26.69    0.12   28.08    0.22

2015   3   25.43   -0.17   27.15    0.03   28.50    0.22

2015   4   25.62   -0.31   27.26    0.24   28.97    0.36

2015   5   26.00   -0.37   26.64    0.45   29.07    0.58

2015   6   26.38   -0.40   24.94    0.00   28.57    0.58

2015   7   26.91   -0.32   23.63   -0.15   28.13    0.66

2015   8   27.70   -0.07   22.75   -0.34   27.81    0.65

 

Source: National Oceanographic and Atmospheric Administration (NOAA)

 

Indeed, but keep in mind, that's for the whole North Atlantic, where as the cold waters is much more regional. As you can see, it doesn't include -ve anomalies earlier this year or at the end of last year, when the cold blob was already well formed.

 

Can you give a link to that data? It seems similar to the AMO (averaged north Atlantic temperatures) but gives different values to the monthly AMO ones here http://www.esrl.noaa.gov/psd/data/correlation/amon.us.data

Edited by BornFromTheVoid
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Posted
  • Location: Hadleigh, Suffolk
  • Weather Preferences: An Alpine climate - snowy winters and sunny summers
  • Location: Hadleigh, Suffolk

Indeed, but keep in mind, that's for the whole North Atlantic, where as the cold waters is much more regional. As you can see, it doesn't include -ve anomalies earlier this year or at the end of last year, when the cold blob was already well formed.

 

Can you give a link to that data? It seems similar to the AMO (averaged north Atlantic temperatures) but gives different values to the monthly AMO ones here http://www.esrl.noaa.gov/psd/data/correlation/amon.us.data

 

Not unexpected but rather frustrating that their are no figures for the various regions of the North Atlantic. I rather suspect "the blob" has been holding down the overall North Atlantic SST, with other areas such as the warmer anomaly off the eastern seaboard of the USA doing their best to raise the SST. It all makes the task of trying to predict the impact of any SST anomaly (when presented at the overall North Atlantic level) even more difficult when there are regional variances.

 

Anyway, apologies I didn't include the links as I normally do. Here they are.

 

The graph was generated by climate4you and states the source data is NOAA. Click on 'Sea Surface Temperatures' and then scroll down until you reach the 'NOAA SST North Atlantic' graph.

http://www.climate4you.com/SeaTemperatures.htm#Sea surface temperatures

 

It is strange that there are different data values shown in your link versus mine, as the base source is NOAA. Here's my source:

http://www.cpc.noaa.gov/data/indices/sstoi.atl.indices

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Posted
  • Location: Ireland, probably South Tipperary
  • Weather Preferences: Cold, Snow, Windstorms and Thunderstorms
  • Location: Ireland, probably South Tipperary

Not unexpected but rather frustrating that their are no figures for the various regions of the North Atlantic. I rather suspect "the blob" has been holding down the overall North Atlantic SST, with other areas such as the warmer anomaly off the eastern seaboard of the USA doing their best to raise the SST. It all makes the task of trying to predict the impact of any SST anomaly (when presented at the overall North Atlantic level) even more difficult when there are regional variances.

 

Anyway, apologies I didn't include the links as I normally do. Here they are.

 

The graph was generated by climate4you and states the source data is NOAA. Click on 'Sea Surface Temperatures' and then scroll down until you reach the 'NOAA SST North Atlantic' graph.

http://www.climate4you.com/SeaTemperatures.htm#Sea surface temperatures

 

It is strange that there are different data values shown in your link versus mine, as the base source is NOAA. Here's my source:

http://www.cpc.noaa.gov/data/indices/sstoi.atl.indices

 

Ah yeah, I see what the issue is. That graph counts the north Atlantic as being the small grey box labelled "N.Atl" below. Hardly representative of the N. Atlantic at all.

 

SST%20GeographicalLocation.gif

 

The AMO includes the N. Atlantic from 0N to 70N, so pretty much the entire, actual, N. Atlantic

 

The graph I posted on the second page of this thread is for the region in the red box. A better representation of the cold blob location.

BCvbwIn.png NwEQc8q.png

 

Here's how things look for August for the same location, now that the data is in.

 

ErpaFX5.png

 

So still lowest on record, but not quite as exceptional as July.

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Posted
  • Location: Hadleigh, Suffolk
  • Weather Preferences: An Alpine climate - snowy winters and sunny summers
  • Location: Hadleigh, Suffolk

Ah yeah, I see what the issue is. That graph counts the north Atlantic as being the small grey box labelled "N.Atl" below. Hardly representative of the N. Atlantic at all.

 

The AMO includes the N. Atlantic from 0N to 70N, so pretty much the entire, actual, N. Atlantic

 

The graph I posted on the second page of this thread is for the region in the red box. A better representation of the cold blob location.

 

Here's how things look for August for the same location, now that the data is in.

 

So still lowest on record, but not quite as exceptional as July.

 

As John McEnroe might say, "they cannot be serious" if they think that tiny square represents the North Atlantic! I just took that as being an 'indicative' illustration of location for geographically challenged people :smile:   I'll try and find a contact address and ask them if they are indeed serious. To me their square looks closer to being the Caribbean than what we would consider to be the NA.

 

Anyway, more of interest is that your latest August SST graph for the red box area is "still the lowest on record". And if their box (area) is also showing a continued downward trend on the running 37 month average, then (for the moment) I guess we can carry on discussing the possible consequences of a cooling North Atlantic SST?

Edited by Blessed Weather
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Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.

There is another interesting graph on the climate 4you site, from the Argo floats series. An 800 metre transect of the North Atlantic current at 59N-30W

 

cN0ucV3.gif

 

Anybody interpret what the recent temperature dip at 800 metres represents.

 

Argo site.   http://www.argo.ucsd.edu/

Edited by Nouska
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Posted
  • Location: Near King's Lynn 13.68m ASL
  • Weather Preferences: Hoar Frost, Snow, Misty Autumn mornings
  • Location: Near King's Lynn 13.68m ASL

There is another interesting graph on the climate 4you site, from the Argo floats series. An 800 metre transect of the North Atlantic current at 59N-30W

 

cN0ucV3.gif

 

Anybody interpret what the recent temperature dip at 800 metres represents.

 

Argo site.   http://www.argo.ucsd.edu/

My first thought looking at that would be instrument error?

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Posted
  • Location: Ireland, probably South Tipperary
  • Weather Preferences: Cold, Snow, Windstorms and Thunderstorms
  • Location: Ireland, probably South Tipperary

As John McEnroe might say, "they cannot be serious" if they think that tiny square represents the North Atlantic! I just took that as being an 'indicative' illustration of location for geographically challenged people :smile:   I'll try and find a contact address and ask them if they are indeed serious. To me their square looks closer to being the Caribbean than what we would consider to be the NA.

 

Anyway, more of interest is that your latest August SST graph for the red box area is "still the lowest on record". And if their box (area) is also showing a continued downward trend on the running 37 month average, then (for the moment) I guess we can carry on discussing the possible consequences of a cooling North Atlantic SST?

 

WRT the general downward trend, here's a graph of the AMO since 2005 with a 12 month trailing average and linear trend.

 

Zrl4YxD.png?1

 

Quite a bit of variability and a moderate downward trend. The annual data would suggest we're due a longer term dip into -ve territory some time soon.

 

DJpKz62.png

 

 

 

There is another interesting graph on the climate 4you site, from the Argo floats series. An 800 metre transect of the North Atlantic current at 59N-30W

 

cN0ucV3.gif

 

Anybody interpret what the recent temperature dip at 800 metres represents.

 

Argo site.   http://www.argo.ucsd.edu/

 

That's quite a drop. Must make sure to keep an eye on that graph.

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Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.

My first thought looking at that would be instrument error?

 

It is possible but the fact it mirrors the surface graph BFTV posted leads me to believe it is accurate. The deeper transect to 2000 metres also shows a very changed profile in the last few years. The data starts from 2004 so presume this is all part of the same monitoring as on the RAPID-MOC website.

 

Jn3tbSc.gif

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Posted
  • Location: Reigate, Surrey
  • Location: Reigate, Surrey

There is another interesting graph on the climate 4you site, from the Argo floats series. An 800 metre transect of the North Atlantic current at 59N-30W

 

cN0ucV3.gif

 

Anybody interpret what the recent temperature dip at 800 metres represents.

 

Argo site.   http://www.argo.ucsd.edu/

 

 

AMO cycle beginning to switch into its negative phase.  The really interesting thing will be to watch to see what impact this has on summer ice in the arctic over say the next 5-10 years. Of course the last time it switched into the prolonged cold phase we had a very severe winter in W Europe around the time of the switch over (give or take a few years); that may have been complete coincidence though!  :D

 

I do wonder though whether the current El Nino will, down the line, result in a warming Atlantic again within the next 12 months - so we're probably not quite at the real switch yet.

Edited by beng
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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

It is possible but the fact it mirrors the surface graph BFTV posted leads me to believe it is accurate. The deeper transect to 2000 metres also shows a very changed profile in the last few years. The data starts from 2004 so presume this is all part of the same monitoring as on the RAPID-MOC website.

 

Jn3tbSc.gif

It could be consistent with recent years' overall loss of sea ice?

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Posted
  • Location: Shepton Mallet 140m ASL
  • Weather Preferences: Cold, snow and summer heatwaves.
  • Location: Shepton Mallet 140m ASL

It could be consistent with recent years' overall loss of sea ice?

 

Would it not be more noticeable back in 2007 to 2012 on the graph though when we had larger overall losses?

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

Would it not be more noticeable back in 2007 to 2012 on the graph though when we had larger overall losses?

That's what I can't quite get my head round, NK. I think it could be that, because the ice-extent is so much smaller than it was, the entire freeze-thaw cycle itself involves less water now than it once did? Or, as you suggest, it could be a lag-effect from previous rapid declines in ice-volume? Then again it could be both, plus whatever else is involved? :cc_confused:  :D

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Posted
  • Location: Hadleigh, Suffolk
  • Weather Preferences: An Alpine climate - snowy winters and sunny summers
  • Location: Hadleigh, Suffolk

With regard above posts about sea-ice loss. Melt water would indeed appear to be an important factor in what's happening in the North Atlantic. Here are some extracts from a paper titled 'Exceptional twentieth century slowdown in Atlantic Ocean overturning circulation' published in March 2015:

 

This study finds that a twentieth-century weakening in the AMOC may be responsible for the unusual cooling in North Atlantic. Consistent evidence from other studies supports these findings and shows a rapid slowdown in the AMOC especially after 1970. This study, however, is the first to point out that this reduction has been unprecedented over the past millennium, and suggests that recent changes in the AMOC are not due to natural climate variability, but instead driven by ocean-freshening effects of climate change. 

 

post-20040-0-82983300-1441740604_thumb.p

Above Figure: AMOC weakness after 1975 is an unprecedented event in the past millennium

 

Plausible real-world explanations for this freshening are anomalous sea-ice export from the Arctic Ocean, increased river discharge and increased melt water from the Greenland Ice Sheet. A freshening trend in the North Atlantic has been observed since the 1970's.

 

post-20040-0-19342400-1441740611_thumb.p

Above Figure: Accumulation of freshwater input from Greenland

 

Increased melt water from glaciers due to global climate change increases the amount of low salinity seawater in the North Atlantic, thereby causing a slowdown in the AMOC. Although a permanent AMOC shutdown in the future remains very unlikely, short-term consequences from sluggish circulation are expected. Likely impacts include a rise in sea level along the US eastern seaboard that would impact cities like New York and Boston, more severe winter storms over Europe...

 

The study was published on the Nature Climate Change website but unfortunately full access requires a payment.

http://www.nature.com/nclimate/journal/v5/n5/full/nclimate2554.html

So the above extracts and diagrams were sourced from Oceanbites website who reported on the study:

http://oceanbites.org/cooling-in-north-atlantic-defies-global-warming/

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Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.

With regard above posts about sea-ice loss. Melt water would indeed appear to be an important factor in what's happening in the North Atlantic. Here are some extracts from a paper titled 'Exceptional twentieth century slowdown in Atlantic Ocean overturning circulation' published in March 2015:

 

This study finds that a twentieth-century weakening in the AMOC may be responsible for the unusual cooling in North Atlantic. Consistent evidence from other studies supports these findings and shows a rapid slowdown in the AMOC especially after 1970. This study, however, is the first to point out that this reduction has been unprecedented over the past millennium, and suggests that recent changes in the AMOC are not due to natural climate variability, but instead driven by ocean-freshening effects of climate change. 

 

attachicon.gifRahmstorf2015_fig21 AMOC.png

Above Figure: AMOC weakness after 1975 is an unprecedented event in the past millennium

 

Plausible real-world explanations for this freshening are anomalous sea-ice export from the Arctic Ocean, increased river discharge and increased melt water from the Greenland Ice Sheet. A freshening trend in the North Atlantic has been observed since the 1970's.

 

attachicon.gifRahmstorf2015_fig41 Runoff and Ice discharge.png

Above Figure: Accumulation of freshwater input from Greenland

 

Increased melt water from glaciers due to global climate change increases the amount of low salinity seawater in the North Atlantic, thereby causing a slowdown in the AMOC. Although a permanent AMOC shutdown in the future remains very unlikely, short-term consequences from sluggish circulation are expected. Likely impacts include a rise in sea level along the US eastern seaboard that would impact cities like New York and Boston, more severe winter storms over Europe...

 

The study was published on the Nature Climate Change website but unfortunately full access requires a payment.

http://www.nature.com/nclimate/journal/v5/n5/full/nclimate2554.html

So the above extracts and diagrams were sourced from Oceanbites website who reported on the study:

http://oceanbites.org/cooling-in-north-atlantic-defies-global-warming/

 

Here's a brand new study on the same subject but with free access.

 

http://onlinelibrary.wiley.com/doi/10.1002/2015GL065276/pdf

 

The conclusions are striking if such a situation should come to pass.

 

fIKyrbd.png

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Posted
  • Location: Solihull, West Midlands. - 131 m asl
  • Weather Preferences: Sun, Snow and Storms
  • Location: Solihull, West Midlands. - 131 m asl

Nouska,

 

A fascinating paper.

 

Can I go into GW speculation mode?......

 

I have been advocating/ speculating that the NAO and NAOC seemed to be associated with the worlds surface temperature (in some way which didn't seem to be taken into account by the models) in the climate threads.. These were discussed  from the graphs I published in March/April timescale, which were obtained from the HADRUTC4 data set.

 

At that time it was not understood and for which I could offer no explanation, other than the rate of change of the  temps in the HADRUT4 data set appeared to show some direct relationship/collaboration with the NAO..

 

I speculated at the time  that the NAO looked to be having something to do with transfer of heat from the southern to northern hemisphere. 

 

This report at least shows that models also can now produce this effect and  also states that it is important to include the effect in future climate models.

 

I  recognize that they do not see the full effect for a few hundred years!!!.

 

However,   I think that this paper, together with one you reported/showed about 2 - 3 weeks ago, on some early models (around 2003) showing an effect of dramatic cooling in the north Atlantic caused by an anomanously long period of northwest/north winds in the Greenland area (lasted 30 years), may offer us some hints as to some of the factors missing in the models today.. It would also suggest that the effects may also 'outlast' the PDO, and possibly be the major feedback signal which can counter the effect of the PDO in the overall CO2 warming signal.

 

This type of effect could also explain the 'non-existent' 'hiatus' - which by the way is now at 18 years and 8 months according to RSS.

 

So, am I adding 2 and 2 and getting 5?

 

I admit my speculation could be totally wrong... we will have to wait and see!!! (Maybe for a long-time!)

 

MIA

 

:sorry::nonono::)

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  • Location: Near King's Lynn 13.68m ASL

With regard above posts about sea-ice loss. Melt water would indeed appear to be an important factor in what's happening in the North Atlantic. Here are some extracts from a paper titled 'Exceptional twentieth century slowdown in Atlantic Ocean overturning circulation' published in March 2015:

 

This study finds that a twentieth-century weakening in the AMOC may be responsible for the unusual cooling in North Atlantic. Consistent evidence from other studies supports these findings and shows a rapid slowdown in the AMOC especially after 1970. This study, however, is the first to point out that this reduction has been unprecedented over the past millennium, and suggests that recent changes in the AMOC are not due to natural climate variability, but instead driven by ocean-freshening effects of climate change. 

 

attachicon.gifRahmstorf2015_fig21 AMOC.png

Above Figure: AMOC weakness after 1975 is an unprecedented event in the past millennium

 

Plausible real-world explanations for this freshening are anomalous sea-ice export from the Arctic Ocean, increased river discharge and increased melt water from the Greenland Ice Sheet. A freshening trend in the North Atlantic has been observed since the 1970's.

 

attachicon.gifRahmstorf2015_fig41 Runoff and Ice discharge.png

Above Figure: Accumulation of freshwater input from Greenland

 

Increased melt water from glaciers due to global climate change increases the amount of low salinity seawater in the North Atlantic, thereby causing a slowdown in the AMOC. Although a permanent AMOC shutdown in the future remains very unlikely, short-term consequences from sluggish circulation are expected. Likely impacts include a rise in sea level along the US eastern seaboard that would impact cities like New York and Boston, more severe winter storms over Europe...

 

The study was published on the Nature Climate Change website but unfortunately full access requires a payment.

http://www.nature.com/nclimate/journal/v5/n5/full/nclimate2554.html

So the above extracts and diagrams were sourced from Oceanbites website who reported on the study:

http://oceanbites.org/cooling-in-north-atlantic-defies-global-warming/

 

The paper has been discussed at RC here (by the main author himself, I believe):

 

http://www.realclimate.org/index.php/archives/2015/03/whats-going-on-in-the-north-atlantic/

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