Senior officials at WWF and the International Union for the Conservation of Nature, IUCN, told AFP they expected the shift to be felt within a month in domestic legislation and by the year end in global climate change negotiations

"He seems to be moving fast," said Julia Marton-Lefevre, Director General of the Swiss-based IUCN, a network of conservation groups, governments and companies. "It's super urgent and he knows it."

"The US reducing its (carbon) impact will already have an impact on the rest of the world," she added.

Carter Roberts, president of the US branch of WWF, said the United States was set to move "from being a laggard and even pariah on some issues to being a leader."

"This election is a turning point, not only in the United States and its actions on the environment, but also because it will have a ripple effect around the world," he said by phone during a meeting of WWF International in Switzerland.

Colleagues were deeply impressed by Obama's inaugural speech, citing especially a "multicultural outlook" that promised bridge-building with emerging and developing countries on the environment, they added.

Roberts expected the ripple effect to have an impact on China first.

Although it has set domestic targets, Beijing has been wary about Obama's campaign promises and is reluctant to commit to new international cuts in carbon emissions unless industrialised economies do more.

"I believe China is ready to take the right steps to a lower carbon economy, they want and need to take the steps with the United States," Roberts said.

Marton-Lefevre said: "China could have an impact on the US - let them sit down and talk."

Key targets for Washington mentioned by the two included a green economic stimulus package, with proposals to renovate US power generation and incentives for home energy saving, federal legislation on carbon emissions, a move to end US isolation from a global climate change treaty, and federal policy on nature conservation and biodiversity.

Despite her optimism, Marton-Lefevre doubted that Obama he would be able to deliver everything he promises and gave a month to assess his administration's environmental team's actions.

At WWF, Roberts questioned the order of action.

"The haven't committed to a timetable yet, the question is where climate (change) sits amongst other priorities," he explained.

On top of outlining policies that break out of the previous administration's mould, Obama has nominated officials and scientists with strong green credentials to key posts dealing with energy, the interior and environment.

In his inauguration speech last Tuesday, he vowed to "roll back the specter of a warming planet" and championed renewable energy.

"Each day brings further evidence that the ways we use energy strengthen our adversaries and threaten our planet," Obama said.

He also addressed other nations "that enjoy relative plenty", saying that they and the United States could no longer consume the world's resources "without regard to effect."

All rights reserved. copyright 2018 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.