Skeptics of climate change have long argued that the ongoing increase in global temperatures is caused by an upward trend of solar activity, particularly the occurrence of sunspots, dating back to the 17th century.
A new study conducted by researchers in the United States, however, has found no evidence of such solar activity culmination that occurred during the 20th century. This suggests that the method of using sunspots to plot climate change can no longer be applied.
The sunspot method, known as the Group Sunspot Number, has been used by scientists to observe space weather, the solar dynamo and even changes in the climate. It has demonstrated an increase in the number of sunspots beginning in 1885 up to 1945 and has culminated in a phenomenon known as the Modern Grand Maximum.
In a new process, dubbed the Sunspot Number Version 2.0, scientists from the World Data Center (WDC), the National Solar Observatory (NSO) and Stanford University recalibrated the existing sunspot method and discovered that there has been a stable activity of sunspots since 18th century, and that there was no such Modern Grand Maximum that occurred.
The research team, led by WDC's Frédéric Clette, NSO's Ed Cliver and Stanford's Leif Svalgaard, presented the findings of their study during the International Astronomical Union(IAU) in Hawaii. They said that the results mirror that of another record for the activity of sunspots known as Wolf Sunspot Number.
The study shows that it would be difficult to establish a link between the natural trends of solar activity and the changes in the climate that have been observed from the 1700s up to the age of Industrial Revolution and the 20th century.
Because of this better understanding of solar activity development, the new Sunspot Number Version 2.0 method could very well cause scientists to reevaluate existing models of climate evolution.
Concerns about sunspots were once again raised after Northumbria University professor Valentina Zharkova reported during the National Astronomy Meeting of the Royal Astronomical Society that the activity of sunspots could decrease by as much as 60 to 70 percent from 2030 to 2040 beginning in the current cycle.
Her forecast stated that global temperatures would significantly drop by several degrees, similar to what occurred during the 17th century. Global warming, however, could potentially offset this reduction in temperatures.
Zharkova's prediction has been met with criticism from fellow scientists who study solar activity and climate change. A majority of experts on the climate argue that changes in the level of solar activity will not have any significant effect on the planet's climate.
Photo: NASA Goddard Space Flight Center | Flickr
