HONOLULU, Aug. 11 (UPI) -- A favorite argument of those who deny the reality of manmade climate change is that sunspots, or solar activity, dictate climate change.
The theory already had holes, but new research suggests the alleged correlation is nonexistent.
In a new study, researchers argue that a sunspot counting method called the Group Sunspot Number is fundamentally flawed. The flaw is responsible for the discrepancy between the Group Sunspot Number and the numbers tallied by another, older counting method called the Wolf Sunspot Number.
The Group Sunspot Number was created in the 1990s by a group of scientists who suggested lacking telescope technology resulted in astronomers lowballing the sunspot totals. The creators of the method claimed their analysis was based on sunspot measurements made by Galileo in 1612, and was a better way to account for the observations of ancient astronomers.
But the two scales disagreed on sunspots and sunspot group totals prior to 1885, as well as a period around 1945.
Now, researchers say that flaw has been eliminated and the sunspot counting method has been recalibrated. The new and improved method, dubbed Sunspot Number Version 2.0, shows that solar activity has not, in fact, been trending upward since the 18th century, but has remained largely the same.
The revelation makes it more difficult for climate change deniers to claim a long-term increase in solar activity is responsible for rising global temperatures.
Most climate scientists have never denied that solar activity may play a role in influencing climate, but have simply questioned the relative effect of that influence -- as compared with factors like greenhouse gas emissions.
But the new numbers will require climate scientists to re-examine climate models and the interplay between temperature and solar activity.
A team of researchers -- including scientists from England, Germany and the United States -- presented their new findings at the International Astronomical Union XXIX General Assembly in Honolulu on Tuesday.
It hasn't been long since the link between sunspots and climate change last made the news. Earlier this year, Valentina Zharkova, a math professor at England's Northumbria University, told an assembly of astronomers that a precipitous drop in solar activity could pave the way for a mini ice age in the 2030s.
That story made the round on the Internet, but was quickly called into question by a variety of scientists, who questioned the significance of solar activity on weather and climate patterns on Earth.