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Past studies have shown that sunspot numbers correspond to warming or cooling trends. The twentieth century has featured heightened activity, indicating a warming trend.  (Source: Wikimedia Commons)

Solar activity has shown a major spike in the twentieth century, corresponding to global warming. This cyclic variation was acknowledged by a recent NASA study, which reviewed a great deal of past climate data.  (Source: Wikimedia Commons)

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Some researchers believe that the solar cycle influences global climate changes.  They attribute recent warming trends to cyclic variation.  Skeptics, though, argue that there's little hard evidence of a solar hand in recent climate changes.

Now, a new research report from a surprising source may help to lay this skepticism to rest.  A study from NASA’s Goddard Space Flight Center in Greenbelt, Maryland looking at climate data over the past century has concluded that solar variation has made a significant impact on the Earth's climate.  The report concludes that evidence for climate changes based on solar radiation can be traced back as far as the Industrial Revolution.

Past research has shown that the sun goes through eleven year cycles.  At the cycle's peak, solar activity occurring near sunspots is particularly intense, basking the Earth in solar heat.  According to Robert Cahalan, a climatologist at the Goddard Space Flight Center, "Right now, we are in between major ice ages, in a period that has been called the Holocene."

Thomas Woods, solar scientist at the University of Colorado in Boulder concludes, "The fluctuations in the solar cycle impacts Earth's global temperature by about 0.1 degree Celsius, slightly hotter during solar maximum and cooler during solar minimum.  The sun is currently at its minimum, and the next solar maximum is expected in 2012."

According to the study, during periods of solar quiet, 1,361 watts per square meter of solar energy reaches Earth's outermost atmosphere.  Periods of more intense activity brought 1.4 watts per square meter (0.1 percent) more energy.

While the NASA study acknowledged the sun's influence on warming and cooling patterns, it then went badly off the tracks.  Ignoring its own evidence, it returned to an argument that man had replaced the sun as the cause current warming patterns.  Like many studies, this conclusion was based less on hard data and more on questionable correlations and inaccurate modeling techniques.

The inconvertible fact, here is that even NASA's own study acknowledges that solar variation has caused climate change in the past.  And even the study's members, mostly ardent supports of AGW theory, acknowledge that the sun may play a significant role in future climate changes."