An estimated 10,000 people rallied in Melbourne on Sunday as part of a national climate-change campaign urging the federal government to set a carbon price.
Australian Conservation Foundation chief executive Don Henry said the big polluters and their supporters were running a scare campaign on the carbon tax but a people-power campaign was gaining momentum.
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"We've got to ramp up people power because in the next three months our parliament's going to decide whether we take action or not," Mr Henry told the Melbourne rally.
Mr Henry said the majority of Australians wanted action on climate change, as shown by tens of thousands of people turning out for Sunday's "Say Yes" rallies across the country.
"We think momentum is building, people power is building, because Australians want action on climate change," he told reporters.
"We know this won't be easy but the time to get moving is right now."
Mr Henry said now was the time to ramp up the campaign supporting a carbon tax.
"I think we're all worried that our parliamentarians won't get over the line, they've blinked a couple of times before," he said.
"So it's the right time for all Australians, from all walks of life, to say, `Hey, come on parliamentarians, no matter what your political colour, we pay your salary, we vote you in, we want action on climate change now and that means a price on pollution'."
'A show of strength'
Greens MP Adam Bandt described the rally as a show of strength from people who wanted real action on climate change.
"What this is is a genuine people-powered movement that is going to ride over the top of Tony Abbott's coal-fired fear campaign," Mr Bandt said after the rally.
The opposition leader last week urged the mining industry to become "political activists" in a last-ditch effort to head off a carbon tax.
The government plans to finalise details of its carbon pricing scheme in early July, ahead of legislation being introduced to parliament by September and a fixed carbon price starting on July 1, 2012.
Mr Bandt said the multi-party climate change committee working on the scheme would meet again this week and throughout June to see if an agreement could be reached about putting a price on pollution.
Asked what minimum price was needed to make a difference, Mr Bandt said: "A price that will be effective and will begin the transition away from coal and towards clean energy."
