WASHINGTON • Mr Scott Pruitt, the head of the Environmental Protection Agency (EPA), has said that carbon dioxide was not a primary contributor to global warming, a statement at odds with the global scientific consensus on climate change.

Speaking of carbon dioxide, the heat-trapping gas produced by burning fossil fuels, Mr Pruitt told CNBC's Squawk Box that "measuring with precision human activity on the climate is something very challenging to do".

He also said there was "tremendous disagreement about the degree of impact" of greenhouse gas build-up.

"We need to continue the debate and continue the review and the analysis," he said.

Mr Pruitt's statement is not consistent with scientific research on climate change, including decades of research by federal agencies. His remarks may also put him in conflict with laws and regulations his agency is charged with enforcing.

Mr Pruitt's remarks also suggest that, as the Trump administration moves forward with unwinding former president Barack Obama's climate change regulations aimed at reining in carbon dioxide pollution, it may not issue replacement regulations, which could put the administration in violation of federal law.

In 2009, the EPA released a legal opinion known as an endangerment finding that, because of its contribution to global warming, carbon dioxide in large amounts met the Clean Air Act's definition of a pollutant that harmed human health.

Under the terms of the Clean Air Act, all such pollutants must be regulated by the EPA.

A federal court then upheld the finding and the Supreme Court declined to hear a challenge to it. Thus, the EPA remains legally obligated to regulate carbon dioxide.

In his January Senate hearing, Mr Pruitt said as head of the EPA he would not revisit that 2009 legal finding.

"It is there, and it needs to be enforced and respected," Mr Pruitt said. "There is nothing that I know that would cause it to be reviewed."

However, energy lobbyists close to the Trump administration have since urged Mr Pruitt, President Donald Trump and their staffs to consider building a legal case against the endangerment finding.

Mr Trump is expected next week to announce an executive order directing Mr Pruitt to begin the legal process of unwinding the climate change regulations on emissions from power plants.

REUTERS