The engineering oceanographer Dr Dan Harrison

Published 20 March 2021
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From tracking tuna across the Pacific Ocean to brightening clouds over the Great Barrier Reef, Southern Cross University’s Dr Daniel Harrison is working to protect our ecosystems before it’s too late. This unfortunately, he says, is likely to be far sooner than most people realise: “I personally think we’re going to start seeing very, very rapid decline of the reef over the next decade.”

Dr Harrison is a senior lecturer and researcher at Southern Cross University’s National Marine Science Centre. He is both an oceanographer and an engineer. His work with colleagues in the United States involves creating satellite data-driven modelling tools to track fish species and help fisheries managers gain environmental information about fisheries. In Australia he is leading a sub-section of the Reef Restoration and Adaptation Program (RRAP). The RRAP is looking at ideas to try and help the Great Barrier Reef adapt to Climate Change and to restore some of the damage already done.

In terms of the fisheries, Dr Harrison explains: “We’ve got these statistical models that predict how many fish are out there and how many we can catch each year safely, but this predominately statistical approach has been around since the 50’s, so our goal was to bring information on the state of the ecosystem into that and promote a more ecosystem based approach,” said Dr Harrison.

Dr Harrison is passionate about using modelling tools that are designing to help avoid bycatch. Bycatch is any species that inadvertently gets caught while targeting another species. Dr Harrison hopes that once they become advanced enough, the satellite data driven tools will help identify the location of both target and bycatch species, when they overlap, and under what conditions this happens. Such knowledge would enable fisheries managers to avoid unnecessary bycatch and potentially create dynamic areas where fishing is prohibited.

The Reef Restoration and Adaptation Program is a collaboration between many of Australia’s Universities including Southern Cross University, The Australian Institute of Marine Science, the CSIRO and the Great Barrier Reef Foundation which is funding the effort in partnership with the Federal Government. Dr Harrison’s team is looking specifically at cooling and shading options including cloud brightening technology, floating reflective surface films and creating a sea fog.

Cloud brightening involves pumping atomized sea water into the air above the reef. “We’re taking seawater and atomising it to incredibly small droplets. Each droplet, which is already infinitesimally small, evaporates and just 3% or so of that is salt. And it’s that tiny little salt crystal that goes on to be a nucleus for a cloud droplet. We’re not actually creating clouds…when the cloud forms there’s a given amount of water content, each droplet needs a nucleus to condense around; if we provide more of these cloud condensation nuclei, the same cloud reflects more sunlight.”

 

So we're out here in the Great Barrier Reef testing the cloud brightening concept. Cloud brightening concept is that maybe we can take seawater atomize it, which is sprayed out from this turbine here and then those droplets will mix up the atmospheric boundary layer and brighten the clouds a little bit.
If we could brighten the clouds just a little bit over the whole summer then we could cool down the water enough to stop some of the coral bleaching. And there's bleaching all around us happening right now it's the third mass bleaching event in just five years.
The logistics for getting everything together for this experiment were huge involving a ton of different universities have been really really great actually working on something that provides a solution and a solution that very much might actually work. As an indigenous person and our waterways, our seas are really important to us it's good to see the scientists start to help the reef.
So we're sailing downwind with the second boat which is going back and forth and at the same time we're sampling with the drone up in the sky and allows us to map how the flume is moving up towards the clouds. So if we find out that this technology works as well as we hope this might buy us a couple of decades but at the same time it's absolutely essential to reduce our emissions.

Coral bleaching is caused by the interaction of sunlight and water temperatures warmer than what corals are accustomed to. While coral can tolerate some additional heat, when this is combined with sunlight, bleaching occurs because when coral becomes too warm it can’t adequately process the photons it’s receiving from the sun. Bleaching can be reduced by either shading the reefs or cooling them down.

“One of the great things about Cloud Brightening is it can potentially do both,” said Dr Harrison.  

The RRAP sub-program team lead by Dr Harrison is also looking at floating reflective surface films and creating a sea fog. Spraying seawater to create a fog, like cloud brightening, would aim to reduce the suns energy reaching the ocean surface but target a much smaller region.

“We’ve got a window that is rapidly closing, to do something, but if we can get some of these ideas to work on a really big scale…modelling suggests it might be enough to alter the trajectory of the reef and help to transition it through this period but only if we also have very, very aggressive action on climate change. There’s such a large amount of warming that’s already locked into the climate system that we need to see really strong action on climate change now,” said Dr Harrison.

“What our modelling does show is that even if all these ideas we’re developing, work really well to the best of our more optimistic predictions, that’s still not going to be enough if the world keeps burning fossil fuels at the rate that we’re doing it – so I’m quite interested in negative emissions technologies.”

Dr Harrison said the other options that we have are trying to take carbon dioxide back out of the atmosphere using carbon sequestration technologies and global interventions to cool the whole planet down, which wouldn’t address the underlying problem, just like cloud brightening doesn’t address the underlying problem.

“Ultimately what needs to happen, what would really make a meaningful change, is government policy. We need government policy to divest in fossil fuels and invest that into driving the change to electric cars and renewable energy sources, and in carbon sequestration technologies that can help by taking some of the carbon dioxide back out of the atmosphere. To implement policy, the tax on carbon which we nearly had but then we lost, I think that would help a great deal.”

Learn more about Dr Harrison's research

Media contact: Content and media, scumedia@scu.edu.au