Almost 3000 scientists from nearly 60 nations have appealed to Prime Minister Malcolm Turnbull and other Australian leaders to halt the CSIRO's plans to halve the number of researchers working on climate monitoring and modelling.

">In a letter that was also sent to the CSIRO's board and chief executive Larry Marshall, the 2900 researchers said the decision to cut 100 full-time positions out of about 140 staff from two units of the Oceans and Atmospheric division "alarmed the global research community".

"The decision to decimate a vibrant and world-leading research program shows a lack of insight, and a misunderstanding of the importance of the depth and significance of Australian contributions to global and regional climate research," the letter said.

"The capacity of Australia to assess future risks and plan for climate change adaptation crucially depends on maintaining and augmenting this research capacity."

The letter follows a statement earlier this week by the World Climate Research Program that the proposed axing risked severing "vital linkages with Australian colleagues and to essential southern hemisphere data sources, linkages that connect Australia to the UK, the US, New Zealand, Japan, China and beyond".

Fairfax Media sought comment about the letter from the CSIRO and the offices of the Prime Minister and Science Minister Christopher Pyne.

Paul Durack, a researcher at the Lawrence Livermore National Laboratory in the US who helped co-ordinate the letter, said Australia played a vital role in monitoring and modelling, particularly for the southern hemisphere.

"Our continued improvement to climate understanding depends very much on Australia's contribution," Dr Durack, a former CSIRO scientist, said.

"In fact, for the Southern Ocean almost a quarter of the ocean observing capacity [using Argo floats] is provided by the Australian program."

Dr Durack hopes the letter will prompt the CSIRO to reconsider the cuts.

Maintaining climate capability, which feeds into learning how Australia can reduce greenhouse gas emissions and identify climate risks, is "more important to the globe now than ever before", he said.

Australia's scientists are also mobilising to find ways to limit the reductions, or secure new homes for the researchers and their programs, Andrew Holmes, president of the Australian Academy of Sciences, said.

The academy a week ago warned that the proposed job losses would cut deeply into programs that had already lost $20 million in the 2014-15 budget.

"I hope we are not in a sinking ship," Dr Holmes said. "I think there is the opportunity for a constructive and positive response.

"Why would you want to throw away something that we're good at, and that's useful?"