Is climate change destroying the Great Barrier Reef?
For some the question is a no-brainer: rising sea temperatures are killing the coral, right?
But there are others, including the Federal Environment Minister, who stop well short of accepting this.
It is the search for clear and irrefutable evidence about the impact of climate change on the reef that is driving researchers from Southern Cross University as they sail across northern Australia on board the CSIRO research vessel Investigator this month.
The scientists are conducting experiments to better understand the role of ‘upwelling’ on nitrogen supply to the Great Barrier Reef.
‘Upwelling – when cold water rises up from the deep ocean floor – is a natural phenomenon caused by winds and currents, but often goes unnoticed,’ said Professor dirk Erler, from the university’s Centre for Coastal Biogeochemistry.
‘It provides essential nutrients for corals and fish. Upwelling also cools the reef, so this is really important as ocean temperatures continue to increase.’
Professor Erler and PhD researcher Tom Glaze are looking to measure the ‘stable isotope fingerprint’ of nitrogen in deep ocean water along the edge of the continental shelf down to 3000m as the RV Investigator travels between Brisbane and Darwin.
‘Once we measure the isotope signature of deep ocean nitrogen we will look for it in the skeletons of corals living on the edge of the reef,’ said Dr Erler.
‘Because we know how old these coral skeletons are we can create a history of upwelling over the past few centuries. The ultimate goal is to determine if upwelling is becoming more or less common as a result of climate change.’
Investigator, Australia’s Marine National Facility, is a cutting-edge multidisciplinary research vessel specifically built for conducting ocean-going science.
“This is an incredible ship with an amazing array of equipment and technology,” said Mr Glaze.
“We can send instruments and water sampling bottles to the bottom of the ocean and watch it in real time, it’s a fantastic opportunity for me as a student to be exposed to all this amazing science.”
The researchers are also using shipboard equipment to measure nitrous oxide, a greenhouse gas, in the deep ocean as well as in the shallow surface water and the atmosphere – the first time this has been done in the Coral Sea.