Scientists are seeking the help of the Australian and US navies to repel Somali pirates who are threatening one of the world's key climate monitoring programmes.

With about a quarter of the Indian Ocean currently off-limits to marine experts, Australian researchers have asked the navies to help them plug a critical gap in their study of international weather patterns.

They hope to deploy about 20 robotic instruments in a no-go area north of Mauritius. The instruments, which record ocean heat and salinity patterns, are programmed to submerge and eventually resurface to upload their data to satellites.

But with piracy in the western Indian Ocean making it too dangerous for commercial or research vessels to deploy the robotic devices, Australia's government research department, the CSIRO, hope naval forces will help them out.

The increase in piracy had serious implications for their understanding of a region which had a major influence in Australian and south Asian weather and climate, said Dr Ann Thresher of the CSIRO. "We can't send anybody in that area, research voyages have been cancelled and I know there's a report of at least one ship that hired an armed escort – that's pretty extreme when you're talking about climate change."

More than 30 nations are involved in the multi-million pound Argo project, in which 3,000 robotic instruments provide data on the heat and saltiness of the world's oceans. The information is of great value to scientists who are able to forecast weather patterns and advise farmers of the likelihood of rainfall and floods.