OCEANS

According to marine scientist Professor Ove Hoegh-Guldberg, a 4‑degree rise in global temperature would radically change marine life in Australia's oceans and is likely to cause 'catastrophic' outcomes. The article says the broad range of changes being reported make it hard to conclude anything other than a collapse of marine ecosystem resources as we move toward average global temperatures of 4°C or higher.

Professor Hoegh-Guldberg warned the Great Barrier Reef would be changed 'beyond recognition' by the end of this century under a 4°C scenario. The reef would face severe losses of coral and associated marine life, undermining the reef's structure and ecological function.

The article says many of Australia's fisheries would change 'beyond recognition' as ocean temperatures rise. Reduced food sources like phytoplankton during breeding times would mean lower fish stocks and widespread starvation among commercially important species, putting fisheries at great risk.

Phytoplankton is described as essential fish food, especially during breeding times. The article reports that changes in ocean temperature would greatly reduce phytoplankton stocks during those critical periods, which would lead to widespread starvation among young fish and lower overall fish populations.

Professor Hoegh-Guldberg said the costs associated with a collapse of marine ecosystems and related impacts from rising sea levels are likely to cost the Australian taxpayer billions of dollars and significantly reduce quality of life. The CSIRO estimates the economic value of Australia's ocean territory at about $52 billion a year, roughly 8% of GDP.

Tourism would be negatively affected. The article states tourism would be hit by large reductions in fish and coral life in the Great Barrier Reef, which would diminish the reef's appeal to visitors and harm reef-dependent tourist businesses.

No. Professor Hoegh-Guldberg rejected the idea that the reef could just migrate south to escape warming. He said coral would have to move about 40 kilometres a year to keep pace with a 4°C temperature rise, but coral species typically disperse only around 10 kilometres or less per generation, so they cannot keep up.

The warnings came from Professor Ove Hoegh-Guldberg, director of the Global Change Institute at the University of Queensland. He made these comments at a conference on global warming in Melbourne, as reported in the article.