The CIA has shuttered its unit dedicated to studying the impact of climate change on national security, shifting its activities elsewhere, an official said Tuesday.

"As part of a broader realignment of analytic resources, this work continues to be performed by a dedicated team in a new office that looks at economic and energy matters affecting America's national security," said CIA spokesman Todd Ebitz.

"The mission and the resources devoted to it remain essentially unchanged."

The Center on Climate Change and National Security was founded in 2009 under the leadership of then CIA director Leon Panetta, who now heads the Pentagon.

It was aimed at studying the security ramifications of climate-related issues such as desertification, rising sea levels, migration and competition for natural resources.

Republican members of the US Congress, many of whom doubt the scientifically accepted evidence that climate change is underway, have opposed the unit since its establishment and unsuccessfully sought to block funding for it.

Panetta was replaced in September 2011 by David Petraeus, who has since resigned over an extramarital affair, and the unit no longer enjoys as much internal support, according to Greenwire, a specialized publication.

Under former president George W. Bush, the United States, one of the world's biggest polluters, opposed international measures such as the Kyoto Treaty designed to slow global warming.

President Barack Obama has now vowed a new push for action on the matter in his second term, saying the United States had a duty to come together to curb emissions in the wake of last month's devastating Superstorm Sandy.

Climate change played little role in the election campaign until days before the vote, when Sandy tore through the East Coast and the Caribbean, killing more than 110 people in the United States alone.

Some US lawmakers take issue with the view of most scientists that industrial emissions of carbon dioxide and other greenhouse gases are causing the planet to warm.

Word of the center's closure comes just days before the opening of an international conference in Doha on global warming.