Corrected sunspot history suggests climate change not due to natural solar trends

Measuring the actual temperature at different parts of the atmosphere supports this.

Also, the number of sunspots varies in a cycle of about 11 years. In recent years, even during the times when the number of cycles decreased, the global temperature continued to increase.

Public Release: 7-Aug-2015
Corrected sunspot history suggests climate change not due to natural solar trends
International Astronomical Union

Until now there was a general consensus that solar activity has been trending upwards over the past 300 years (since the end of the Maunder Minimum), peaking in the late 20th century -- called the Modern Grand Maximum by some [1].

This trend has led some to conclude that the Sun has played a significant role in modern climate change. However, a discrepancy between two parallel series of sunspot number counts has been a contentious issue among scientists for some time.

The two methods of counting the sunspot number -- the Wolf Sunspot Number and the Group Sunspot Number [2] -- indicated significantly different levels of solar activity before about 1885 and also around 1945. With these discrepancies now eliminated, there is no longer any substantial difference between the two historical records.

The new correction of the sunspot number, called the Sunspot Number Version 2.0, led by Frédéric Clette (Director of the World Data Centre [WDC]-SILSO), Ed Cliver (National Solar Observatory) and Leif Svalgaard (Stanford University, California, USA), nullifies the claim that there has been a Modern Grand Maximum.

The results, presented at the IAU XXIX General Assembly in Honolulu, Hawai`i, today, make it difficult to explain the observed changes in the climate that started in the 18th century and extended through the industrial revolution to the 20th century as being significantly influenced by natural solar trends.

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