The oceans are in a worse state than previously suspected, according to an expert panel of scientists.
The panel was convened by the International Programme on the State of the Ocean (IPSO), and brought together experts from different disciplines, including coral reef ecologists, toxicologists, and fisheries scientists.
In a new report, they warn that ocean life is "at high risk of entering a phase of extinction of marine species unprecedented in human history".
They conclude that issues such as over-fishing, pollution and climate change are acting together in ways that have not previously been recognised. The impacts, they say, are already affecting humanity.
A coral reef specialist, Ove Hoegh-Guldberg from the University of Queensland, was one of the experts involved.
He told Checkpoint that, if nothing changes, mass extinctions could be expected in the next 50 to 100 years.
He said studies across the oceans are showing a steady erosion of oxygen levels, which is what has happened in former mass extinction episodes.
"It is alarming, there's no doubt about it ... This is a system that stretches across 71% of the earth's surface. It is the major climate regulator, it determines our weather. It's really is our life support system.
"And what we're seeing is, what we thought was a robust and resilient system, is now changing quite breathtakingly fast."
The full report is to be released later this week.