USGS - science for a changing world

Kansas Water Science Center

Climate for the 21st Century and Beyond from a Calibrated Solar-Output Model

By Charles A. Perry, U.S. Geological Survey, Lawrence, KS, 66049, U.S.A. and Kenneth J. Hsu, ETH, Zurich, Switzerland


The debate on the cause and the amount of global warming and its effect on global climates and economics continues unabated. One helpful key to estimating future climate may be found in examining the timing of significant events in world history with a climate change model. Although the causes of climate change are not completely understood, an important causal candidate is changing total solar output. Examination of cycles in various climate-proxy data shows a tendency for the data to emulate a fundamental harmonic sequence of a basic solar-cycle length (11 years) times 2N, (where N=1,2,3....13).

A simple additive model for total solar-output variations was developed by simply superimposing a progression of fundamental harmonic cycles with slightly increasing amplitudes. These cycles begin with the basic solar-activity cycle having an observed total variation in luminosity of 0.1% and end with the full glacial cycle of about 90,000 years with an estimated total variation of 0.6%. Geophysical evidence of significant climate events was used to calibrate the timeline of the model. Then the model is compared with archaeological and historical evidence of warm or cold climates during the Holocene. The historical evidence of periods of several centuries of cooler climates worldwide called "little ice ages," similar to the period AD 1300 to 1850 and reoccurring approximately every 1,300 years, corresponds well with fluctuations in the solar-ooutput model amplitudes. A more detailed examination of the climate sensitive history of the last 1,000 years further supports the validity of the model. Extrapolation of the model into the future suggests a gradual cooling during the next few centuries with intermittent minor warm-ups and a return to near little-ice-age conditions within the next 500 years. This cool period then may be followed by a return to altithermial conditions similar to the previous Holocene Maximum in approximately 1,500 years.

Additional information on Solar Irradiance and Streamflow can be found at:

Perry, C.A., and Hsu, K.J.,, 2001, Climate for the 21st century and beyond from a calibrated solar-output model [abst.], in West, G.J., and Buffaloe, L.D., eds., Proceedings of the Seventeenth Annual Pacific Climate Workshop, May 22-25, 2000, Two Harbors, Santa Catalina Island, California: Interagency Ecological Program for the San Francisco Estuary Technical Report 67, p. 120.

To request a paper copy of this abstract, email: