Wednesday, September 27, 2006
The energy output from the Sun has increased significantly during the 20th century, according to a new study.I don't know if this will pan out though it seems to be weel investigated. If it does then any warming over the last century will be explained. What can be said with certainty is that, with this & other explanations involving increased methane release from plants, more cows etc., is that the warming effect is so small & the degree of uncertainty over everything is so great that it cannot possibly be honestly said that the anthropogenic warming, let alone catastrophic anthropogenic warming is anywhere close to being proven, or even a clear prime hypothesis.
Many studies have attempted to determine whether there is an upward trend in the average magnitude of sunspots and solar flares over time, but few firm conclusions have been reached.
Now, an international team of researchers led by Ilya Usoskin of the Sodankylä Geophysical Observatory at the University of Oulu, Finland, may have the answer. They examined meteorites that had fallen to Earth over the past 240 years. By analyzing the amount of titanium 44, a radioactive isotope, the team found a significant increase in the Sun's radioactive output during the 20th century.
Over the past few decades, however, they found the solar activity has stabilized at this higher-than-historic level.
Prior research relied on measurements of certain radioactive elements within tree rings and in the ice sheets covering Greenland and Antarctica, which can be altered by terrestrial processes, not just by solar activity. The isotope measured in the new study is not affected by conditions on Earth.
The results, detailed in this week's issue of the journal Astronomy & Astrophysics Letters, "confirm that there was indeed an increase in solar activity over the last 100 years or so," Usoskin told SPACE.com.
The average global temperature at Earth's surface has risen by about 1 degree Fahrenheit since 1880 ......