CANBERRA: Scientists have warned that the world might once again be heading towards an Ice Age, with global warming approaching a possible end.

Evidence in support of this theory has come from pictures obtained from the US Solar and Heliospheric Observatory, which showed no spots on the sun, thus determining that sunspot activity has not resumed after hitting an 11-year low in March last year.

A sunspot is a region on the sun that is cooler than the rest and appears dark.

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Some scientists believe a strong solar magnetic field, when there is plenty of sunspot activity, protects the earth from cosmic rays, cutting cloud formation, but that when the field is weak - during low sunspot activity - the rays can penetrate into the lower atmosphere and cloud cover increases, cooling the surface.

According to Australian astronaut and geophysicist Phil Chapman, this might have caused the world to cool quickly between January last year and January this year, by about 0.7C.

"This is the fastest temperature change in the instrumental record, and it puts us back to where we were in 1930," said Dr Chapman.

"If the temperature does not soon recover, we will have to conclude that global warming is over," he added.

Dr Chapman has proposed preventive, or delaying, moves to slow the cooling, such as bulldozing Siberian and Canadian snow to make it dirty and less reflective.

"My guess is that the odds are now at least 50:50 that we will see significant cooling rather than warming in coming decades," he said.