Sunspots in 8,000-year record - scientists
The past 70 years have seen the longest and most intense period of sunspot activity for 8,000 years, scientists said today.
Researchers reconstructed a record of sunspot activity for the last 11,000 years by studying a heavy form of carbon in tree rings.
Sunspots increase the flow of charged particles hurtling out of the Sun towards the Earth.
They in turn deflect cosmic rays which normally bombard the Earth’s atmosphere.
Reactions from this bombardment generate the heavy carbon-14 isotope. So when trees absorb the carbon, they indirectly carry a historical record of what is happening on the surface of the Sun.
The findings, from a German team led by Sami Solanki at the Max-Planck Institute in Katlenburg-Lindau, appeared today in the journal Nature.
In an accompanying article, Paul Reimer of Queen’s University, Belfast, wrote: “The models reproduce the observed record of sunspots extremely well, from almost no sunspots during the 17th century to the current high levels.”
The record should make it possible to track the long-term solar influence on climate and changes in the Sun’s magnetic activity.
Some scientists have speculated that variations in the amount of light and heat from the Sun are linked to sunspots and climate change.
But the authors of the new research say our current period of high sunspot activity could not be the main driver of global warming.
