Based on the cooling spiral of recent solar cycles, scientists from University of California, San Diego believe the next “grand-minimum” is just decades away, during which the Sun will be seven per cent cooler.

A grand-minimum, according to the study, is a period of very low solar activity, which will lead to lower temperature on earth.

During the grand-minimum in the mid-17th century, named Maunder Minimum, the temperature dropped low enough to freeze the Thames River.

However, the cooling is not uniform around the globe.

In spite of the chilling weather in Europe during the Maunder Minimum, other areas such as Alaska and southern Greenland warmed.

The phenomenon appears to offer a natural solution to global warming, but scientists invalidated that idea.

They explained that the cooling effect of the grand minimum could merely slow down global warming, but cannot stop it.

Scientists estimate that the grand minimum would probably only result in cooling the earth by about 0.25 per cent between 2020 and 2070.

The finding has been published in the Chicago-based journal Astrophysical Journal Letters.(Xinhua/NAN)