This paper was just published today in the Journal of Ocean Engineering and Science. It seems to be definitive refutation of Mann and Rahmstorf’s claims, and quells the alarm bells that climate proponents have been ringing for years, not just in Mannian science that’s been refuted time and again, but in Hollywood movies like The Day After Tomorrow. Doom and Gloom just isn’t happening when you look at the real-world data whereas Rahmstorf and Mann prefer to use computer models. In an email from the lead author Albert Parker, he noted:
[The AMOC is] apparently quite stable and not following the anthropogenic CO2 emissions
There is no real evidence for a diminishing trend of the Atlantic Meridional Overturning Circulation
A. Parker, C.D. Ollier
The Atlantic Meridional Overturning Circulation (AMOC) is part of the great ocean “conveyor belt” that circulates heat around the globe. Since the early 2000s, ocean sensors have started to monitor the AMOC, but the measurements are still far from accurate and the time window does not permit the separation of short term variability from a longer term trend. Other works have claimed that global warming is slowing down the AMOC, based on models and proxies of temperatures. Some other observations demonstrate a stable circulation of the oceans. By using tide gauge data complementing recent satellite and ocean sensor observations, the stability of the AMOC is shown to go back to 1860. It is concluded that no available information has the due accuracy and time coverage to show a clear trend outside the inter-annual and multi-decadal variability in the direction of increasing or decreasing strength over the last decades.
The Atlantic Meridional Overturning Circulation (AMOC) is a critical part of the Earth’s climate system transporting heat from the tropics and Southern Hemisphere toward the North Atlantic. The recent period of monitoring with ocean sensors cover is very short and does not permit the separation of short term variability from long term trends , ,, ,  and .
A recent study by Rahmstorf et al.  claims, based on models and proxies, that global warming is slowing down the circulation of the ocean. They say that their computational maps of temperature patterns over the 20th century show a significant area of cooling in the Northern Atlantic near Greenland and suggest that this cooling may be due to a reduction in the AMOC over the 20th century and especially after 1970. They believe the AMOC weakness after 1975 is an unprecedented event in the past millennium. They claim that further melting could contribute to further weakening of the AMOC.
The models and proxies of Rahmstorf et al.  predict the overturning circulation is slowing down as the greenhouse gases warm the planet and the melting ice adds freshwater to the ocean, but actual observations so far as Willis  and Rossby et al. show no signs of any slowdown in the circulation.
Every approach proposed so far for the AMOC has indices that may or may not represent the long term trend in the AMOC depurated of the variability. Every approach interprets changes in the indices as supporting either no AMOC slowdown or a clear evidence for a slowdown. Either may be right or wrong, but they cannot both be right. Here we argue that there is no unquestionable evidence of any change in the AMOC signal if not variability.
The long-term sea level variations along the east coast of North America appear to be different north and south of Cape Hatteras. And the differences in north-south sea level change can be argued to reflect changes in the AMOC which then adjust the sea surface temperature (SST) patterns that make up the Atlantic Multi Decadal Oscillation (AMO). A stronger AMOC should lead to warmer temperatures in the Atlantic marking a positive AMO so the AMOC and AMO should be linked. Long-term AMO oscillations then argue for an oscillating AMOC over the past 50 years without a long-term trend.
There is no reliable measure of the AMOC direct or based on proxies that covers a sufficient time window to show a clear trend beyond inter-annual and multi-decadal variability. Claims of strengthening or reducing of the AMOC are therefore pure speculation
Our paper discusses the limits of all the indices and studies proposed so far for the AMOC, also introducing a novel long term index based on tide gauge results that is integrated with the recent satellite observations of sea surface height and temperature, salinity and velocity from profiling buoys. The paper concludes that there is no undoubtable evidence of a weakening or strengthening of the AMOC, as no index returns an accurate measure of the AMOC strength over a time window long enough to clear the longer term trend of the multi-decadal variability. The most likely pattern is oscillatory about a longer term trend not sufficiently well delineated.
Full paper, open source is here: http://www.sciencedirect.com/science/article/pii/S246801331500008X