Sun's Cycles Can Forecast Floods, Drought?

Carolyn Barry in Sydney, Australia
for National Geographic News
December 10, 2008

The sun's fluctuations can help predict extreme climatic events on Earth decades ahead of time, new research suggests.

Solar cycles are 11-year phases during which the sun's activity ebbs and flows, accompanied by an increase in sunspots on the sun's surface. (Watch a video of how solar storms cause "sun quakes.")

The cycles, which are driven by the sun's magnetic turbulence, may influence weather systems on Earth, particularly the El Niño-Southern Oscillation, a periodic climatic system associated with floods and droughts mostly in the Southern Hemisphere.

"The sun is the engine of our climate," said lead study author Robert Baker, of the University of New England in Australia.

"It's like a vibrating string—its past vibrations can be used to predict future vibrations."

Those vibrations are the cyclical "twisting and untwisting" of magnetic fields that cause the sun's poles to flip at the start of each new cycle.

(Related: "Sun's Power Hits New Low, May Endanger Earth?" [September 24, 2008].)

Climate and Sun Similarities

Longer magnetic cycles of about 90 years and 400 years are also found in astronomy records.

The Southern Oscillation Index, which measures the El Niño-Southern Oscillation system, seems to correspond with a 90-year sun cycle, Baker found.

For instance, the current index reading closely follows a trend observed in the 1920s.

Periods of greater solar disturbances are associated with rainy periods, whereas a calmer sun dovetailed with times of drought in Australia, Baker said.

Continued on Next Page >>


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