Four former heads of the US Environmental Protection Agency (EPA) who served under Republican presidents have urged lawmakers to stop bickering over whether climate change is real, and start finding solutions.
Global warming is a polarising issue in American politics, with most Republicans questioning the science behind it and most Democrats calling for stricter pollution limits.
In the absence of legislation to curb fossil-fuel burning, US President Barack Obama this month urged the EPA to set carbon-pollution standards for power plants that would slash emissions by 30 per cent by 2030.
His proposal also called for more global cooperation to curb pollution and for US financial incentives for renewable energy.
But the regulations "will harm our fragile American economy", Republican Senator John Barrasso told the Senate Committee on Environment and Public Works on Wednesday.
"Thousands of people will lose their jobs," he added, describing the measures as "all pain and little gain".
The four former EPA administrators who testified at the hearing on Wednesday served under presidents Richard Nixon, Ronald Reagan, George H.W.Bush and his son, George W.Bush.
As a group, the quartet penned an op-ed in
The New York Times last year that said there was no longer any credible debate over whether humans were causing climate change.
At the hearing, they urged US lawmakers to put aside their differences. "The two parties were able to rally around a common purpose in the early days of environmental policymaking," said Christine Whitman, the EPA chief from 2001 to 2003. "It is urgent that they do so again."