Australian scientists warn that rising concentrations of greenhouse gases are dramatically changing the way oceans function.

Many studies often overlook the effects of climate change on marine ecosystems because of their complexity.

But in a paper published today, a leading Australian marine scientist has pulled together research from the past 10 years, which he says paints a grim picture.

The Global Change Institute director at the University of Queensland, Professor Ove Hoegh-Guldberg, says the world is seeing a decline in major ocean ecosystems like kelp forests and coral reefs.

Along with a US colleague, Professor Hoegh-Guldberg says his research has found fish are getting smaller, there are changes in the distribution of marine life and there are more frequent diseases in marine organisms.

"We are seeing changes in the way food chains work in the ocean," he said.

"We are seeing massive declines in some sorts of organisms and if we continue down this pathway we get into conditions which have no analogue to anything we've experienced."

Professor Hoegh-Guldberg says water pollution, over-fishing, increased ocean acidification and rising temperatures are to blame.

"Over the past several thousand years, conditions have been remarkably stable in many parts of the planet, so life tends to adapt to those local conditions," he said.

"Now when we take those conditions and change them rapidly as we have over the past 150 years, we are essentially expecting organisms to suddenly evolve, and of course, evolution takes a long amount of time."

The research has been published today in the journal Science, which is devoting a section of the latest issue to the ocean.

The chief scientist at the Centre for Australian Weather and Climate Research, John Church, who wrote the editorial for the journal, says the changes to marine ecosystems will affect how the ocean absorbs carbon dioxide.

He says the changes have gone too far and society has no choice but to adapt to the altered oceans and climate.

"The ocean is a central part of the climate system. They absorb large amounts of carbon dioxide, delaying the impact of climate change, and they influence both regional and global climate," he said.

"If we are going to be able to adapt cost effectively rather than in response to major events, then we need to know what might happen into the future.

"Knowing these things in advance requires observing and understanding the global oceans."