Length of the Solar Cycle: An Indicator of Solar Activity Closely Associated with Climate

Abstract

It has recently been suggested that the solar irradiance has varied in phase with the 80- to 90-year period represented by the envelope of the 11-year sunspot cycle and that this variation is causing a significant part of the changes in the global temperature. This interpretation has been criticized for statistical reasons and because there are no observations that indicate significant changes in the solar irradiance. A set of data that supports the suggestion of a direct influence of solar activity on global climate is the variation of the solar cycle length. This record closely matches the long-term variations of the Northern Hemisphere land air temperature during the past 130 years.

Human contribution to climate change remains questionable

“…Shorter variations, on the timescale of decades, appear to be caused by atmosphere-ocean interactions and changes in ocean circula tion. Alternatively they could be caused by external factors, such as variations in solar irradiance (solar "constant") [Soon et al, 1996;Lean et al, 1995] or in solar activity (ultraviolet radiation or solar corpuscular radiation); there are suggestive correlations with temperature [Friis-Christensen and Lassen, 1991] and with cloudiness [Svensmark and Friis-Christensen, 1997], but as yet no convincing physical mechanism.…”

Decadal-scale variability of warm season temperature in Beijing over the past 2650 years

“…This is probably attributable to the Gleissberg cycle of solar variations, frequency ranging between 100 and 70 years [17][18][19][20], centered about 88 years. The 25-22, 12 and 9 year cycles are also associated with solar cycles [21,22]. These indicate that solar variation was also one of the drivers for the decadal-scale variability of warm season temperature in Beijing over the past 2650 years.…”

A comparison between two empirical downscaling strategies

“…Some AOGCMs that do not require flux-correction in order to give a stable and reasonable climate description, however, are emerging. Still, the state-of-the-art models may not have a sufficiently good representation of a number of unresolved physical processes that potentially can affect the climate, such as clouds and aerosols (Ramanathan et al, 1989;IPCC, 1995;Hansen et al, 1998), landscape processes (Hansen et al, 1998;Couzin, 1999), the biosphere (Facchini et al, 1999;Joos et al, 1999), ice (Ganopolskey et al, 1998;Zreda et al, 1999), and solar activity (Reid, 1987;Friis-Christensen and Lassen, 1991;Kelly and Wigley, 1992;Lean and Rind, 1998;Wilson, 1998;Shindell et al, 1999). Because of the crude representation of these processes in the present AOGCMs and the chaotic nature of the climate system, one cannot expect them to reproduce the evolution of regional climate anomalies exactly as seen in the observational records.…”