The four high-profile scientists Michael Raupach, John Church, Pep Canadell and James Risbey have broken ranks with CSIRO to make personal submissions to a Senate inquiry into the Rudd Government's emissions trading scheme.

They claim tougher targets are needed to avoid Australia being ''locked in'' to dangerous climate change, and list 14 recent scientific findings that support their argument.

The rebel scientists cannot comment on their decision because they are public servants. But a CSIRO source said they could risk censure and possible career repercussions by taking such a public stand against the Government's controversial greenhouse reduction targets.

A CSIRO spokesman denied there was a gag on its scientists participating in the inquiry, and said the four were, ''welcome to make comment as long as they are not representing CSIRO''.

All four CSIRO scientists are world leaders in their various areas of climate research. Dr Raupach co-chairs the Global Carbon project, which oversees international research on the global carbon cycle. Dr Church chairs the scientific committee for the Geneva-based World Climate Research Program, Dr Canadell is executive director of the Global Carbon project and Dr Risbey has been involved in global climate research for more than 20 years.

A CSIRO source told The Canberra Times the group was determined to ''present new scientific findings to the Senate inquiry that it believes are crucial to shaping Australia's future greenhouse policies''.

The source said the scientists made their decision to go ahead with personal submissions after CSIRO management ruled out any participation in the inquiry by Australia's peak science body on the grounds that it would require comment on government policy.

A CSIRO spokesman said the inquiry's terms of reference, ''went to the policy of the Government's carbon pollution reduction scheme, and in line with our public comment policy, we don't comment on government policy''.

The scientists had been told to, ''make it absolutely clear'' they were not speaking on behalf of CSIRO. If asked to testify, they will be required to take formal leave and travel at their own expense.

For more, pick up a copy of today's Canberra Times