A study published in the journal Science has concluded that climate change is altering oceans and rainfall worldwide.

A team of three researchers looked at ocean data over the period 1950 to 2000.

They found salinity levels have changed in all the world's oceans, wetter areas are experiencing more rain and drier areas have become drier.

Susan Wijffels from the CSIRO says she expects the trend to continue.

"The answer of how much more is going to be in the future depends on how much more warning there is going to be," she said.

"So if we stay on a high emissions pathway we might see warming up around three degrees, which will give us maybe a 24 per cent change in our water cycle."

The authors say this could have implications for global food security.

The study was jointly funded by the Department of Climate Change, the Bureau of Meteorology and the CSIRO.