North Atlantic Thermohaline Circulation: conflict between science and the media

By Clare Boston

New research published in Geophysical Research Letters suggests that there has been no significant change in the strength of the Atlantic Meridional Overturning Circulation (AMOC) between 2002 and 2009.  The AMOC forms part of the Thermohaline Circulation (THC) and is responsible for bringing warmer waters to Western Europe from the Gulf of Mexico.  The research has recorded changes in sea surface height using satellites since 1993 and, alongside records of temperature, salinity and velocity, has been used to estimate changes in the AMOC.  Whilst there appears to have been a small increase in mean overturning since 1993, the research suggests that any changes are simply part of the natural cycle.  This is opposed to earlier research by the UK’s National Oceanography Centre’s in 2005 which suggested a weakening of Atlantic circulation.  Both studies demonstrate the need for records over longer timescales in order to separate any significant trends from natural variability.

Changes in scientific opinion have huge potential to add to confusion amongst the general public about current and future climate change.  In a new article in Area, Neil Jennings and Mike Hulme write that such confusion has also been caused by the misrepresentation of scientific articles in the media.  Their study examined the portrayal of THC articles by newspapers, suggesting that the popularisation of the term ‘gulf stream’ has resulted in it being regarded as synonymous with THC, leading to seemingly conflicting scientific opinions reported by the media.  Sensationalist headlines suggesting an imminent collapse of the ‘gulf stream’, despite the 2007 IPCC report regarding it as ‘very unlikely’ in the next century, were also reported to have misled public understanding of the complex scientific debate.  No doubt recent headlines, such as “Gulf stream ‘is not slowing down’” from the BBC News website on Monday, will add to this confusion and to the growing public unrest about climate science as a whole.

Willis, J. K. (2010), Can in situ floats and satellite altimeters detect long-term changes in Atlantic Ocean overturning?, Geophys. Res. Lett., 37, L06602, doi:10.1029/2010GL042372.

Read the BBC News Article “Gulf stream ‘is not slowing down'”

Jennings, N. and Hume, M. (2010). UK newspaper (mis)representations of the potential for a collapse of the Thermohaline Circulation. Area, Early view.

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