New Paper Finds Solar Amplification By Which Sun Controlled Climate Over Past 250 years

  • Date: 01/04/14
  • The Hockey Schtick

A new paper published in Nature Communications finds a “clear correlation” between solar and volcanic activity and a 5-year lagged response of the Atlantic Multidecadal Oscillation [AMO] over the past 250 years, which in turn drives the climate of the Northern Hemisphere.

This may represent yet another solar amplification mechanism by which tiny variations in solar activity have large-scale effects on climate.

According to the paper, “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.”

“This phenomenon is called the Atlantic Multidecadal Oscillation (AMO), which consists of relatively warm periods lasting thirty to forty years being replaced by cool periods of the same duration. The researchers were able to read small systematic variations in the water temperature in the North Atlantic in measurements taken by ships during the last 140 years.”

“Although the temperature fluctuations are small — less than 1°C — there is a general consensus among climate researchers that the AMO phenomenon has had a major impact on the climate in the area around the North Atlantic for thousands of years, but until now there has been doubt about what could cause this slow rhythm in the temperature of the Atlantic Ocean.”

“Another model explains the AMO as being driven by fluctuations in the amount of solar energy received by the Earth, and as being affected by small changes in the energy radiated by the Sun itself and the after-effects of volcanic eruptions. Both these factors are also known as ‘external forces’ that have an impact on the Earth’s radiation balance.”"However, there has been considerable scepticism towards the idea that a phenomenon such as an AMO could be driven by external forces at all — a scepticism that the Aarhus researchers now demonstrate as unfounded”
“It should also be pointed out that these fluctuations occur on the basis of evenly increasing ocean temperatures during the last approximately fifty years — an increase connected with global warming,”
“During the last century, the AMO has had a strong bearing on significant weather phenomena such as hurricane frequency and droughts — with considerable economic and human consequences. A better understanding of this phenomenon is therefore an important step for efforts to deal with and mitigate the impact of climate variations,”
“The results provide a new and very important perspective on the AMO phenomenon because they are based on data and not computer models, which are inherently incomplete. The problem is that the models do not completely describe all the physical correlations and feedbacks in the system, partly because these are not fully understood. And when the models are thus unable to reproduce the actual AMO signal, it is hard to know whether they have captured the essence of the AMO phenomenon.”
“An interesting new theory among solar researchers and meteorologists is that the Sun can control climate variations via the very large variations in UV radiation, which are partly seen in connection with changes in sunspot activity during the Sun’s eleven-year cycle. UV radiation heats the stratosphere in particular via increased production of ozone, which can have an impact on wind systems and thereby indirectly on the global ocean currents as well,”

Temperature fluctuations: Atlantic Ocean dances with the sun and volcanoes

March 31, 2014
Source: Aarhus University
Summary:

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 can now show that solar activity and the impact of volcanic eruptionshave led this dance during the last two centuries.

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