20/12/2018

'Greater Warming': Different Species Under Threat

Fairfax - Ben Weir

Entire ecosystems are under threat due to warming oceans with parts of the Australian coast stretching from Sydney to Adelaide experiencing the most stress, experts warn.
Eight of the 10 warmest years of sea surface temperatures have been recorded since 2010 contributing to coral bleaching, oceans acidifying and altering the habitats of different species, a joint study by the Bureau of Meteorology and CSIRO has found.
"The warming has been most noticeable, particularly around the south-east of the continent, and it's not just coral reefs that are impacted but kelp forests and commercial fisheries," the bureau's head of climate monitoring, Dr Karl Braganza, said.
Trends in sea surface temperatures in Australia from 1950 to 2017. Credit: Bureau of Meteorology
Rising CO2 levels change the pH make-up of oceans and as waters become more acidic this impacts everything from plankton to coral, the study found.
“There has been a southwards migration of subtropical and tropical fish species, down the east coast of Australia associated with this warming,” Dr Braganza said.
Further north, rising temperatures have contributed to coral bleaching on the Great Barrier Reef in 2016 and 2017, with parts experiencing "thermal stress" and potentially the loss of many types of coral in future heatwaves.
Bleaching along the Great Barrier Reef is a common sight for divers. Credit: XL Catlin Seaview Survey
“In February to May 2016, the bleaching was associated with some of the warmest sea surface temperatures ever recorded,” Dr Braganza said.
Sea levels globally have also increased around 3 centimetres per decade in recent years, with rises in northern and south-east Australia higher than the average around the world. (See chart below)
“Rising sea levels have implications for impacts on infrastructure in our coastal regions and coastal erosions so it is important to think about what that looks like around Australia,” CSIRO director of climate change, Dr Helen Cleugh said.
The rate of sea level rises around Australia by satellite observations from 1993 to 2017. Credit: CSIRO
Rising ocean temperatures and levels impact climate change more broadly with around 90 per cent of the extra energy created by greenhouse gases stored in the ocean.
“Oceans play a really important role in modulating the rate and pace of our changing climate,” Dr Cleugh said.
The State of the Climate 2018 report, to be released on Thursday, also predicts a longer fire danger season in south-eastern areas due to rising temperatures. While other regions of the country will experience more time in drought.
Fire weather conditions are worsening, particularly in the south and east of the country.
Credit: Bureau of Meteorology
"The amount of climate change expected in the next decade or so is similar under all plausible global emission pathways, however by the mid-21st century higher ongoing emissions will lead to greater warming," the report's summary said.
The fifth annual report comes after recent UN climate talks in Poland ended with an agreement to increase transparency of national emissions-reduction pledges, but failed to deal with how to raise aid for developing nations and standard accounting rules for carbon credits.

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