This deserves it’s own post!;-)A.M.
by Christina Troelsen for Aarhus News
Aarhus, Sweden (SPX) Apr 04, 2014

Ocean temperature has been regularly measured since 1870, which makes it possible to calculate a mean temperature at each point for the period 1870 to the present day. Ocean temperature varies throughout the year and there are significant variations due to weather systems and over longer timescales. These illustrations show how the average temperatures over 20-year intervals have varied between cold (blue) and warm (red) periods. This variation is called the Atlantic Multidecadal Oscillation, abbreviated to AMO. Illustration courtesy Bo Holm Jacobsen, Aarhus Universitet. For a larger version of this image please go here.

Natural fluctuations in the ocean temperature in the North Atlantic have a significant impact on the climate in the northern hemisphere. These fluctuations are the result of a complex dance between the forces of nature, but researchers at Aarhus University can now show that solar activity and the impact of volcanic eruptions have led this dance during the last two centuries.

Imagine a ballroom in which two dancers apparently keep in time to their own individual rhythm. The two partners suddenly find themselves moving to the same rhythm and, after a closer look, it is clear to see which one is leading.

It was an image like this that researchers at Aarhus University were able to see when they compared studies of solar energy release and volcanic activity during the last 450 years, with reconstructions of ocean temperature fluctuations during the same period.

The results actually showed that during the last approximately 250 years – since the period known as the Little Ice Age – a clear correlation can be seen where the external forces, i.e. the Sun’s energy cycle and the impact of volcanic eruptions, are accompanied by a corresponding temperature fluctuation with a time lag of about five years.

In the previous two centuries, i.e. during the Little Ice Age, the link was not as strong, and the temperature of the Atlantic Ocean appears to have followed its own rhythm to a greater extent.

The results were recently published in the scientific journal Nature Communications.

In addition to filling in yet another piece of the puzzle associated with understanding the complex interaction of the natural forces that control the climate, the Danish researchers paved the way for linking the two competing interpretations of the origin of the oscillation phenomenon.

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