The ABC has a look at some of the campaigning over the carbon tax - Carbon's Bill.

CHRIS CLARK: But a $26 carbon price has been welcomed by some.

JOHN CONNOR, CLIMATE INSTITUTE: Not a bad starting point. It will drive changes in the way in which generation - energy generation - is delivered right now.

CHRIS CLARK: But it's not enough for others.

SIMON O'CONNOR, ACF: If Australia's serious about tackling climate change $26 is not enough and we're really going need to see the price at a much higher level.

CHRIS CLARK: As for managing the transition to a low-carbon economy, Professor Garnaut wants the politics taken out of the decision making and three independent bodies set up: A committee to establish emissions-reduction targets; an agency to oversee the carve-up of compensation; and a carbon bank to regulate the emissions trading scheme.

MATTHEW WARREN, CLEAN ENERGY COUNCIL: We've seen independent bodies like the Reserve Bank handle very difficult decisions like setting interest rates. We think there's real merit in going down this path and looking at that for a carbon price.

Pro tax groups held rallies around the country today - the SMH has a report on the 8000 people at the SYdney rally (apparently Melbourne had over 10,000 as well - Thousands rally in support of carbon price.

As many as 8000 people have rallied in Sydney to urge the federal government to set a price on carbon, as part of a national climate change campaign in cities across the country.

Holding placards with slogans such as "cut carbon pollution, unlock clean energy" and "say yes to cutting carbon pollution", they gathered at Sydney's Prince Alfred Park this morning to deliver a message: climate change is happening, and something needs to be done.

"What people are asking for is an ambitious price (on carbon), an investment in renewable energy," rally organiser and national director of GetUp, Simon Sheik, said. "Today is a big day, because today Australian's will ask their government for a price on carbon."

Simultaneous rallies were being held in most capital cities as the second stage of the "Say Yes" campaign launched late last week by actors Cate Blanchett and Michael Caton.

The advertisement, which urges Australians to say yes to the federal government's proposed carbon emissions tax, stirred controversy among some sections of the media.

Community climate advocate Ramya Krishnan slammed the controversy surrounding Ms Blanchett's contribution to the campaign. "I hear about families who are struggling just like everyone else who want to live in a better world for their children to grow up. The shock jocks don't speak for Western Sydney, and neither does Tony Abbott."

Police said the Sydney crowd numbered between 7500 and 8000.