The Australian government came under attack for its environmental policies from Tim Flannery, the scientist it named as citizen of the year just a day earlier.
The leading environmentalist and author slammed Australia as the "worst of the worst" on global warming, highlighting its failure to sign the Kyoto Protocol.
"There's no doubt this government's been dragging the chain," Flannery told public radio.
"I've said in the past that Australia has been the worst of the worst in terms of addressing climate change ... but I'm hopeful that we'll see over this year some movement."
Flannery said by refusing to ratify the Kyoto agreement on reducing greenhouse emissions, Prime Minister Howard's government had held back the rest of the world.
"We've lost a decade of inaction and we've held the world back really from addressing this issue because we haven't been part of Kyoto. So we need to move doubly swiftly now and this year is the year we need to see that action," Flannery told Sky News.
In his acceptance speech Thursday, Flannery warned he would continue to criticise anyone he thought was pursuing "wrong-headed" policies in this area.
Flannery welcomed Howard's new 10 billion dollar (7.7 billion US) plan to protect Australia's dwindling water supplies but warned that was just part of the environmental jigsaw puzzle.
Howard, who insisted until late last year that there was little evidence for global warming, said he was not embarrassed by the criticism from the Australian of the Year on Australia Day, the country's major holiday.
"Does it embarrass me? No it doesn't," Howard told commercial radio.
"We do live in a democracy and I'm not so thin-skinned and not so desiring in uniformity that I want every Australian of the Year to engage in fullsome praise of the government -- that would be ridiculous."
Although Howard now admits "climate change is occurring", he said he remained unconvinced of Flannery's arguments about the need to back Kyoto.
"We've got to remember that many of the international rules in this whole area particularly Kyoto have been written by Europeans to suit Europeans with scant regard for the interests of countries such as Australia," he said.
