Mike Mann on the Ocean Conveyor

March 25, 2015

More from my extended interview with Mike Mann. If you did not see the video this week on Mike’s headline grabbing new paper (with Jason Box and lead author Stefan Rahmstorf) covering the North Atlantic Current, make sure you see that now.

Here Mike gets deeper into the Atlantic Meridional Overturning Circulation – and what changes in it mean for global weather.

Science 2.0:

A 10 year project to observe and analyze regular data about ocean circulation and how it impacts on Britain’s climate has provided new insight into Atlantic Meridional Overturning Circulation (AMOC), a major system of currents in the North Atlantic.

10 years is too short a time to be meaningful but it is an important milestone. Since 2004, the project team has been monitoring the AMOC at 26.5N degrees, near where it carries its maximum heat, using instruments moored at 30 locations across the Atlantic between the Canary Islands and the Bahamas – so-called fixed arrays. The arrays’ instruments measure the temperature, salinity and pressure of the ocean, from which the AMOC’s strength and structure can be calculated.

Twice-daily estimates of the AMOC have been made every day since the start of the project, providing a significant increase in recorded data. Prior to this, measurements had only been taken during five separate ship surveys – one survey every ten years since the 1950s. The data collected is then calibrated and analyzed to see what changes have taken place.

Until recently it had been widely thought that the AMOC couldn’t be measured in such a consistent way – and there have been some surprising findings.

Firstly, it had been thought that the strength overturning of the AMOC would weaken due to climate change. However, the ocean sensors have detected that the AMOC is now declining faster than anticipated (Smeed et al. 2014), which could potentially have a long-term impact on Britain’s climate. Secondly, the results revealed that the AMOC was significantly more variable than had been previously thought. Thirdly, the data also appeared to confirm that the AMOC had a direct impact on Britain’s winter weather, which could be specifically seen with respect to the harsh winter of 2010/11.

The measurements showed that the strength of the AMOC in 2009/10 was much lower, which affected sea surface and atmospheric temperature – and seemed to directly affect Britain’s weather months later.

The slowdown in the AMOC in 2009/10 also raised sea levels in New York by 13 cm – 4 times the global average sea level rise.

5 Responses to “Mike Mann on the Ocean Conveyor”

  1. redskylite Says:

    What I really appreciated about this paper was the fact it was co-authored by distinguished scientists from widely separated institutions, which again emphasizes the scientific consensus.

    Unified papers across continents and universities/institutions demonstrate consensus and although scientists often consider themselves as “cats” or non herd-able animals, this is much too big a concern and must be tackled as a team.

    The findings are not a great surprise, just happening a lot faster than projected by modelling as it is in the Arctic and Antarctic melts. .

    Authors:

    Article:Rahmstorf, S., Box, J., Feulner, G., Mann, M., Robinson, A., Rutherford, S., Schaffernicht, E. (2015): Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation. Nature Climate Change (online) [DOI:10.1038/nclimate2554]

    Professor Stefan Ramstorf:Potsdam University (Germany)
    Professor Jason Box: Geological Survey of Denmark and Greenland.
    Dr. Michael E. Mann:Earth System Science Center at Pennsylvania State University


  2. I wonder if there is a contributing factor of recent standing wave/blocking patterns on the west coast driving a regional high Eastern Pacific SST anomaly but also forcing the jet stream, laden with Asian mid and upper troposphere aerosols to plunge down from the arctic and produce a large regional SST cooling anomaly that contributes to the observed cool patch in the N. Atlantic.


  3. […] @@ Massive Melting Slows Major Atlantic Current by decreasing the salinity of the North Atlantic, which helps slow down the Atlantic oceanic conveyor belt. This massive current and other marine conveyors belts worldwide are responsible for redistributing massive amounts of heat, thus influencing weather worldwide. […]


  4. […] VIDEO: Mike Mann on the Ocean Conveyor (Climate Crocks) […]


  5. […] @@ Massive Melting Slows Major Atlantic Current by decreasing the salinity of the North Atlantic, which helps slow down the Atlantic oceanic conveyor belt. This massive current and other marine conveyors belts worldwide are responsible for redistributing massive amounts of heat, thus influencing weather worldwide. […]


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