I'm not good at communication: CSIRO head

CSIRO boss Larry Marshall will be quizzed about the science body's latest moves by a Senate inquiry.

As he works through job cuts at the nation's peak science body, the head of the CSIRO has admitted to a Senate inquiry he's not very good at politics or communication.

Larry Marshall already has said he'd do things differently after facing a backlash over a restructure he announced in February.

"I'm not very good at communications and I'm not very good at politics and that's been shown quite clearly," he conceded to senators in Canberra on Wednesday.

The CSIRO has scaled back to 40 the number of climate scientist positions that will be abolished, with officials telling the inquiry in Canberra it will save about $6 million a year.

Overall 275 jobs will go, down from the original expectation of 350.

They include about 15 from the Oceans and Atmosphere division in Hobart, 30 from Aspendale in Melbourne and 10 to 15 in Canberra.

Dr Marshall said where the cuts will be made was "mid-stream", but there will be a call for voluntary redundancies first.

The chief executive's appearance followed the announcement on Tuesday of a national climate research centre in Hobart, employing 40 full-time scientists through a decade-long commitment.

Dr Marshall denied the announcement was a marginal seat strategy or that it came from government.

It followed discussions with staff and stakeholders, including the Bureau of Meteorology and the chief scientist.

"Hobart was just the obvious choice," he said.

Dr Marshall used the start of the hearing to share a drawing his daughter - who is turning 11 on Wednesday - did as part of a school project.

Turn off the switch and save the planet, it read.

"She's a budding scientist," her father said.

The CSIRO Staff Association has renewed calls for Science Minister Christopher Pyne to declare a moratorium on job cuts until after the July 2 election.

"An independent review and subsequent overhaul of CSIRO's executive management structure is obviously necessary and long overdue," the association's Sam Popovski said.

"More broadly, it's time for all political players to show their cards and reveal practical policies to repair and restore our national science icon."