Sunspots reaching 1,000-year high
Here's more inconvenient news from solar researchers. Even though our sun is quiet at the moment while we are in between peaks in the 11 year sunspot cycles, scientists based at the Institute for Astronomy in Zurich used ice cores from Greenland to construct a picture of our star's activity in the past.
Researchers extended the record into the past by measuring isotopes of Beryllium-10 (created by cosmic rays entering our upper atmosphere, which then drifts earthward and is trapped in the ice) in Greenland ice cores. Based on both observations and ice core records, we are now at a sunspot peak exceeding solar activity for any time in the past thousand years."
The number of cosmic rays entering our atmosphere is modulated by the suns magnetic and solar wind activity, which modulates earth's magnetic field, setting up conditions to either allow more or deflect more cosmic rays entering the upper atmosphere.
They say that over the last century the number of sunspots. which are a proxy indicator of solar magnetic activity, rose at the same time that the Earth's climate became steadily warmer. According to climate scientists, the Sun’s radiance has changed little during this period. But looking back over 1,150 years, Solanki found the Sun had never been as bright as in the past 60 years.
“The change in solar brightness over the past 20 years is not enough to cause the observed changes in our climate. But the indirect effects (such as the cosmic ray to cloud connection) may be larger, and the range of their influence is unclear, so more study is needed,” he added.
Comments
I'm curious as to why the solar brightness isn't enough to cause any supposed changes in the last 20 years? After all, the margin of error in our temperature measurements is as great as any so-called observed changes. Seems to me that even a slight change in the sun is going to have a large impact. It certainly does based on the angle of the Earth to the sun.
*** Reply: You have a point, I'll see what I can do to find the answer and present it here.
Posted by: Jeff | April 11, 2007 07:46 AM
Without doing any research on the subject I can come up with two speculations.
One) is that the angle of the earth in relation to the sun is several orders of magnitude more significant than overall average output of the sun so any immediate effects are washed away or obscured by other climate mechanisms and
Two) is that the process of global dimming (which seems to have a lot more scientific merit than the usual blow from global warming alarmists) may be a mitigating factor.
Posted by: David Walton | April 13, 2007 04:31 PM
Oops, that should have read "...more significant than the changes in the overall output of the sun..."
Oh, well.
Posted by: David Walton | April 14, 2007 08:55 AM