HOUSTON, March 3 -- As another round of storms hit much of the United States Sunday and lingered on Monday, a U.S. expert told Xinhua that climate change could be behind this year's extreme winter.

During the past two months, several rounds of deadly storms have enveloped most parts of the U.S. continent, dumping heavy snow and grounding flights, paralyzing traffic and shutting down schools and local governments.

The normal distribution of air in the northern hemisphere has been disrupted or weakened, explained Prof. Ronald L. Sass with Rice University.

The low pressure system over the Bass Island or up in the north of Hudson Bay are usually controlled by the polar jet stream. But once the polar jet stream weakens, the cold air starts to meander or move southward, causing the extreme temperatures seen in many parts of the U.S., Sass said.

"What caused that meandering happening is something else. It could be due to climate change," he pointed out.

This year's winter storms are longer in duration, as the polar cold air is sluggish this year and stays at a particular location for a longer time, he explained.

In a contrast, a record high temperature was registered in Greenland, which can cause additional ice melting, and an extremely hot January was experienced in Cuba.

All these unusual and extreme conditions are caused by human's intense activity in the environment, with increasing greenhouse gas emissions, Sass said.

Sass called for the diversifying of sources of energy and a lessened dependence on fossil fuels by utilizing sources such as wind power, solar power, nuclear power, hydroelectric and thermal-generated energy and geothermal energy.

Sass said some people, especially fossil fuel lobbyists and industry advocates, deny the impact of climate change because they don't want their interests hurt.

He believes the lead to curb climate change could be taken, perhaps surprisingly, from the U.S. military. Though he did not elaborate, he said the U.S. Army has been "very active" in addressing the issue.

Sass urged all countries to face the problem immediately instead of waiting for worsened outcomes.

"The problem is whether you pay now or you pay later. People like to pay later because somebody has to do the paying. Mitigating is paying now. We need to do that immediately," he said.

He stressed the need for global cooperation to resolve the issue, and suggested the U.S. and China could be major players in combating climate change.

"The U.S. and China, among others, have to cooperate with each other. The two countries are the principal members of greenhouse gases," he said, "If the U.S. and China would decide to reduce the greenhouse gases significantly, I think the rest of the world will come along with that."