The east coast of Australia is now considered one of the fastest warming areas in the region. The CSIRO says fish are moving south in search of cooler waters, and marine heatwaves like the recent one off Western Australia will cause major damage to corals and fisheries.
Presenter: Environment Reporter Sarah Clarke
Tim Ingleton, NSW Department of Environment
Alistair Hobday, CSIRO
Russell Reichelt, Great Barrier Park Marine Authority
CLARKE. Every month, for the last 70 years, the ocean temperature has been recorded at the port hacking station off New South Wales. It's one of a network of sites set up around Australia observing coastal conditions including salinity, and ocean temperatures. Tim Ingleton is from the NSW department of environment.
INGLETON. "They are able to record those temperatures a couple of times per second so we're getting 4 or 5 readings per metre of water depth so we now have data being collected on every metre of water from the surface to the bottom".
CLARKE. With records dating back since the 1940's, scientists are getting the most accurate snapshot of the warming trend. Alistair Hobday is from the CSIRO.
HOBDAY. "The background rate of ocean warming has been about 0.7 of a degree over the last 100 years, we've seen warming on the east coast of Australia a bit over 2 degrees in that same period of time and we expect that warming to continue for the next 40 to 50 years so in about the year 2050 it'll be around 2 degrees warmer than it is today. The CSIRO says the east coast is one of the fastest warming areas of Australia. It's for that reason, fish and other marine creatures are heading south in search of cooler waters. "Overall another 45 fish species have moved into Tasmania's waters as a result of this warming that's about a third to a quarter of the total fish in this region. We've also seen changes in inter-tidal animals about 50 per cent of snails and limpets have moved further south in a 50 year period. There's been coastal fish move south, a sea urchin has also moved further south. So we're seeing these changes through the ecosystem.
CLARKE. While it creates new fisheries, there are also downsides. Scientists are monitoring marine heatwaves. One was recorded off Western Australia with ocean temperatures 5 degrees above average over 2 weeks. While it cant be directly linked to climate change, Alistair Hobday says events like these may become more frequent.
HOBDAY. "We expect those warm events to become more common in the ocean but this is the most dramatic one we've observed in human history".
CLARKE. As the oceans warm, corals also struggle. Before 1979, the Commonwealth says there were no records of bleaching on the Great Barrier Reef. Since then there have been at least 9 episodes, 3 of them considered major. Russell Reichelt is the chairman of the great barrier reef marine park authority.
REICHELT. "Global warming on the ocean temperature is variable around the world but not withstanding it's the single greatest threat to the long term future of the great barrier reef. So climate change, global warming which leads to mass coral bleaching is my most serious concern for the future health of the reef".