WASHINGTON – Four former Environmental Protection Agency administrators – all veterans of Republican administrations – are urging lawmakers to take action on global climate change, which one warned carries an “enormous consequence for our future.”

“We all know, after all, that the earth’s climate is changing,” former New Jersey Gov. Christine Todd Whitman, who headed the EPA under President George W. Bush, told the Senate Subcommittee on Clean Air and Nuclear Safety. “We also know that human activity, although not solely responsible, as we should freely acknowledge, is both contributing to that change and increasing the risk that we will push the environment beyond the point upon which we can repair it.”

Those contributing to the problem, Whitman said, have “an obligation to contribute to its solution.”

Whitman was joined by William Ruckelshaus, the agency’s first administrator during the administration of President Richard Nixon; William K. Reilly, who served under President George H.W. Bush; and Lee Thomas, who held the post under President Ronald Reagan. All agreed that while a legitimate scientific debate exists over the pace and effects of climate change, there is no question that the earth is warming and that the human race is contributing to the change.

“The models of the world’s leading scientists predict rising seas, drought, floods, wildfires and more severe and frequent storms,” Rckelshaus said. “We are seeing impacts already.”

Ruckelshaus told the panel that the world’s oceans absorb 25 to 30 percent of produced carbon – an element thought to contribute to global climate change.

“The culprit is the same carbon that originated from fossil fuels that is contributing to planetary warming,” Ruckelshaus said.

If the U.S. fails to take action, Ruckelshaus noted, “nothing much will happen in the rest of the world.”

“Not taking action is a choice,” he said. “It is a choice that means we leave to chance the kind of future we want and opt out of the solution to a problem that we are a big part of.”

Reilly warned that change is underway “and we can expect to see many more disruptions, more intense storms, more wildfires, the spread of pests and diseases, storm surges that overwhelm coastal communities, heat waves and other impacts on our health, on water resources, on food production and on other sectors of our economy.”

“The longer we delay, the more adverse the impacts will be and the more expensive to address them,” he said. “Reducing greenhouse gas emissions, especially carbon dioxide, can help fend off more draconian impacts later this century.”

The U.S., Reilly said, has an advantage in addressing the issue: technology and innovation.

“We have the know-how, the ingenuity, the entrepreneurial spirit, the ability to demonstrate leadership in tackling this challenge,” he said.

But if the four former GOP administrators were hoping for a political consensus on the issue, they left disappointed. Sen. David Vitter (R-La.), ranking member on the Senate Environment & Public Works Committee, rejected “extreme claims” regarding global climate change over the past three decades, asserting that “the devastating impacts of global warming failed to come true.”

The earth’s climate, Vitter said, “has, is, and always will be changing” and many of the recent claims regarding global warming’s impact on the weather “were found to be without merit.” Rather, what has come to pass is “the economic calamity that befalls nations that head down the path President Obama unilaterally selected for America. It provides us a window into our future – and it looks bleak.”