New research suggest that the sun has been in the same routine for 290 million years. Scientists are now looking at petrified tree rings for clues on the sun's behavior throughout time. Ancient tree rings from the Permian period recorded an 11-year cycle of wet and dry periods. These fluctuations in climate are caused by the ebbing and flowing of solar activity. The discovery pushes back the earliest evidence of today's 11-year solar cycle by millions of years.
According to Nat Gopalswamy, a solar scientist at NASA's Goddard Space Flight Center, that the sun's activity has been at this pattern of activity for a very long time. Around every 11 years, the sun's frequency of sunspots, solar flares and its brightness completes one round of waxing and waning. The intensity of sunlight reaching Earth are altered by these solar changes. These activities may affect the composition of the stratosphere and rates of cloud formation according to some scientists. This in turn could change rainfall rates and influence tree growth.
The key to understanding these cycles may lie in ancient trees locked within their petrified trunks. Volcanic eruptions buried an ancient forest in what is now southeast Germany. These eruptions occurred roughly 290 million years ago. Ludwig Luthardt and Ronny Rößler, paleontologists from the Natural Museum in Chemnitz, Germany have identified tree rings in the remains of fossilized trees.
The plants showed how much they grew each year by the measurement of their tree rings. The researchers discovered a cycle in their growth rates. The cycle lasted an average of 10.62 years. Long rises and falls in annual rainfall rates are reflected in the cycle. Over the last few hundred years, the length of sunspot cycles were seen to be on an average of 10.44 to 11.16 year length.
Petrified wood is a fossil. These fossils are formed when plant material is buried in sediment and protected from decay. Groundwater rich in dissolved solids then replace the original plant material with silica, calcite and pyrite or other inorganic material. Specimens that exhibit clearly recognizable plant features such as bark and woody structures are common with petrified wood as reported in an article by Geology.com.
According to paleoclimatologist Adam Csank of the University of Nevada, Reno, whether the tree ring cycles and the solar cycles is connected is still uncertain. Studies suggest that it not possible to clearly identify sunspot scycle in modern tree ring records. Other factors such as changes in the Earth's climate system or periodic outbreaks of insect population may contribute to the width of the tree rings as reported in Science News.
