Kuang said human activities are concentrated north of the equator, which quickens the global warming process in the northern hemisphere.

The heated air, carrying the greenhouse gas carbon dioxide, rises and circulates to the southern hemisphere.

As the air loses its heat high in the atmosphere, the dense air, loaded with carbon dioxide, sinks and brings cold air from the upper atmosphere with it.

“And the cold air causes the south part of the Earth to become colder,” Kuang said.

When carbon dioxide builds up in the south, the process reverses, with cold air descending on the northern hemisphere.