He faced a small and friendly audience of think tank regulars, reporters and Republican political staffers. At the end of a brief Q-and-A session, an audience member noted that the US and Australia once had a “great alliance in opposing the Kyoto Protocol”, until Labor ratified the treaty, and asked if Abbott would overturn that ratification in office.

Abbott, whose one-word description of climate change has not gone unnoticed here, did not take the bait. Well not entirely anyway.

“I think it’s important to do what we reasonably can to reduce emissions,” he began, before adding a quick qualifier. “Argument will rage backwards and forwards about the magnitude of the climate change issue.”

He outlined his proposed emission reduction fund and added that in Australia, “there is a company called Linfox, which is our biggest transport company, that reckons they’ve cut emissions by 35 per cent by training their drivers to take their foot off the accelerator pedal".

Times have changed.

When he arrives in DC later this month as Prime Minister, Abbott’s most significant meeting will be in the White House with a president whose administration will be defending new regulations to cut carbon emissions by power plants by 30 per cent from 2005 levels by 2030, according to reports.

And the timing is no mistake.  Obama, who has long believed that climate change is real, caused by human activity and presents an immediate danger that must be addressed by government action, is not only seeking to reduce emissions from the US with the new regulations.

He is positioning the US to be better able to influence other nations in a series of upcoming United Nations climate talks concluding in Paris next year.

"The Paris Agreement will be heavily influenced by the sense of whether the US is taking the issue of climate change seriously or not," Jennifer Morgan, director of the climate and energy program at the World Resources Institute, an environmental think tank, told the National Journal. "If the administration does propose regulation that is ambitious and demonstrates leadership to decarbonise the power sector, it will certainly inspire more ambition from other countries."

The UN has already recognised the proposed US regulations, to be detailed on Monday in the US, as a diplomatic tool.

The UN’s top climate change official, Christiana Figueres, said in a statement on Sunday that the announcement would “send a good signal to nations everywhere that one of the world's biggest emitters is taking the future of the planet and its people seriously.

"I fully expect action by the United States to spur others in taking concrete action."

Well, maybe, though it is not clear that she has met Tony Abbott.

Either way, hers is the argument the Obama administration will rely on to counter domestic opponents who say action on climate change is pointless unless other nations move first.