The Great Barrier Reef has been in trouble for years, causing scientists to look at an unconventional technique called “cloud brightening” which would artificially increase the number of clouds above the Reef.
Last year, Daniel Harrison of the University of Sydney, told the MIT Technology Review that “cloud brightening is the only thing we’ve identified that’s scalable, sensible, and relatively environmentally benign” for fixing what ails the Great Barrier Reef.
The Reef’s problems are myriad. It is still recovering from a devastating multi-year spell of bleaching, which has negatively impacted its appeal as a tourist attraction. The result is that the famously biodiverse ecosystem, which contains 2,900 individual reefs and 900 islands, has gone quiet. The degraded soundscape signals that the Reef could be attracting up to 40 percent fewer fish.
Cloud brightening seeks to solve the underlying problem of warming waters, considering how coral grows optimally between 73 and 84 degrees Fahrenheit (23 and 29 degrees Celsius). This is distinct from solving the problem of global warming, even though one is caused by the other. The plan is to create a device similar to a snow-making machine.
Harrison, who is still focused on cloud brightening a year later, would want sea water to be pumped through a filter and sprayed out of small nozzles, creating tiny water droplets. A fan would then send the water droplets into the atmosphere. That seawater would then evaporate as it rose in the sky. The only thing left would eventually be a particle of salt around which other water droplets would condense, brightening existing clouds.
“That one droplet creates an aerosol particle that then grows 15 million times in size into a cloud droplet,” Harrison tells the Sydney Morning Herald.
These brighter clouds would then deflect solar radiation, reducing surface water temperatures by around half a degree Celsius. The technology is still in its early stages.
As a hypothetical, cloud-brightening has roots going back to 1990 when British scientists proposed the idea as a solution to global warming as a whole. There are skeptics of the concept specifically regarding the Great Barrier Reef, including Ken Caldeira of the Carnegie Institute of Science. The issue isn’t the underlying science of cloud-brightening, but if the Great Barrier Reef has the right type of clouds that could benefit from increased density.
“I just don’t think there are enough clouds of the right type there that would be susceptible to marine cloud brightening,” hetold the Technology Review in 2017.
Harrison disagrees, but also believes there must be a variety of approaches needed to allow the Reef to “resist, repair and recover,” to quote his lab’s parent organization. Part of the Reef Restoration and Adaptation Program, led by the Australian Institute of Marine Science, Harrison is one of several scientists funded by the Australian government looking at long-term solutions for the Great Barrier Reef.
The Great Barrier Reef has a storied and resilient history, surviving through 30,000 years and multiple catastrophes, related to the Earth’s own dramatic natural history. These catastrophes have included too much oxygen and rising waters. For an animal that provides a home for so many other creatures, coral needs very specific conditions to live. Cloud-brightening could make their lives a little easier.
Source: Sydney Morning Herald