One of CSIRO's main climate science units planned to slash four out of five researchers, all but eliminating its monitoring and climate modelling research, a new document reveals.

The cuts are contained in an analysis for the Oceans & Atmosphere division, dated January 25, 2016. CSIRO handed over the document to the Senate committee investigating plans to slash 350 staff overall, and it has been made public on the Senate's website.

Doubts over the rationale and planning of the cuts flared on Tuesday in another CSIRO section facing deep job losses, with many Land & Water staff walking out of a meeting with chief executive Larry Marshall.

"People got fed up of having their questions marginalised, trivialised, and with being lied to," one senior researcher told Fairfax media. He added that about half those attending walked out, with division's head, Paul Hardisty, among them.

"We understand CSIRO scientists are passionate about their science and also about some of the changes to the structure of their organisation," a CSIRO spokesman said, declining to elaborate on the meeting. "CSIRO is committed to continuing to have open and transparent dialogue with staff and hearing staff views and concerns."

The new document, though, highlights the extent of the original cuts being considered by CSIRO before pressure – including from thousands of international scientists – prompted a scaling back of the job losses.

The Earth System Assessment unit – which includes the climate models used by the Bureau of Meteorology and the team analysing greenhouse and other gases at Tasmania's Cape Grim research station – was to have its 81-strong staff slashed to 16, the analysis shows.

The remaining tally included as many as six post-doctoral researchers, and would have left just the aerosols and air-quality teams, Fairfax Media has been told.

The Oceans & Climate Dynamics unit, which includes sea-level research and ocean observations, was to lose 31 of its 71 staff, the document shows.

"Some long-standing government clients will be impacted by this realignment," the document cites as among the "key risks" of the plan. "This will require some management given that we are electing to make these changes rather than [be] forced by government funding changes."

A spokesman for CSIRO said the organisation stood by comments made by executives including Dr Marshall to Senate estimates. These include an estimate that half of the 140 staff in the main climate units would be retained.

The document "only partly" reflects the situation and that conversations had been many and are ongoing, the spokesman said.

Greens Senator Janet Rice, however, said the document reveals the original plan, "and they've been back-pedalling ever since".

"Not only did they not have any consultation with the Bureau of Meteorology, the Australian Antarctic Division [and other agencies], they had no idea of the impacts," Senator Rice said.

The analysis also omitted from the list of risks the contribution that would be lost to international science and the value to the Australian economy of being able to predict climate change, she said.

Dr Marshall has said CSIRO plans to hire 350 new staff over the next two years to tap new growth areas. These sectors include climate mitigation – or cutting carbon emissions – and adapting to the climate changes that are inevitable.

Scientists, though, have told the Senate committee investigating the CSIRO that adaptation work would be much harder to do unless Australia is able to predict the rate of change and where its impacts will hit the hardest.

The document shows the net reduction in full-time staff in the O&A division would save just $6.5 million a year. That calculation was based on $8.8 million in salaries and $2.7 million in lower operating costs, with the gains set against $5 million in lost revenue.

"It's a pretty bad deal – you cut about 110 staff all together and you recover almost nothing," one senior scientist told Fairfax Media. "You also ruin the reputation [of CSIRO] and the lives" of the staff let go.

Dr Marshall is expected to be grilled on the document when he fronts the Senate committee, now planned for April 7.