The United States refused Monday to sign onto a Group of Seven pledge that calls the Paris climate accord the "irreversible" global tool to address climate change.

The G7 environment ministers issued a final communique Monday after their two-day meeting, the first since the United States announced it was withdrawing from the Paris climate pact. In a footnote to the communique, the United States said it wouldn't join with the other six countries in reaffirming their Paris commitments, but said it was taking action on its own to reduce its carbon footprint.

"The United States will continue to engage with key international partners in a manner that is consistent with our domestic priorities, preserving both a strong economy and a healthy environment," the footnote read.

As a result, the U.S. said it would not join those sections of the communique on climate and multilateral development banks.

The head of the U.S. Environmental Protection Agency, Scott Pruitt, had attended the first few hours of the summit Sunday, but left to attend a Cabinet meeting in Washington.

Presenting the communique Monday, Italy's environment minister, Gian Luca Galletti, called the Paris accord "irreversible, non-negotiable and the only instrument possible to combat climate change." He said the other G7 countries hoped to continue "constructive dialogue" with the U.S., but insisted on the Paris parameters.

"Everything else for us is excluded," he said.

The 2015 Paris agreement aims to prevent the Earth from heating up by 2 C since the start of the industrial age. Since the world has already warmed about 1.1 C since the Industrial Revolution, the accord aimed at making sure the threshold was not breached with each nation curbing heat-trapping emissions.

All but few scientists say the overwhelming majority of warming is man-made, as do dozens of scientific academies and professional societies. Scientists have known since the 19th century that burning coal, oil and gas spews carbon dioxide into the air, which then acts like a blanket to trap heat on Earth.

President Donald Trump announced the U.S. was withdrawing from the Paris accord earlier this month, framing it as a "reassertion of America's sovereignty." He has said the U.S. could try to re-enter the deal under more favourable terms, but Italy, France and Germany have said the Paris accord cannot be re-negotiated.