https://www.technologyreview.com/s/604211/scientists-consider-brighter-clouds-to-preserve-the-great-barrier-reef/
<https://www.technologyreview.com/s/604211/scientists-consider-brighter-clouds-to-preserve-the-great-barrier-reef/>
# A scientist surveys bleaching damage on the Great Barrier Reef.
# TANE SINCLAIR-TAYLOR | ARC CENTRE OF EXCELLENCE CORAL REEF STUDIES
Sustainable Energy
<https://www.technologyreview.com/topic/sustainable-energy/>
Scientists Consider Brighter Clouds to Preserve the Great
Barrier Reef
As bleaching devastates the critical ecosystem for a second
year in a row, marine scientists are getting desperate.
* by James Temple
<https://www.technologyreview.com/profile/james-temple/>
*
* April 20, 2017
Agroup of Australian marine scientists believe that altering
clouds might offer one of the best hopes for saving the Great
Barrier Reef.
For the last six months, researchers at the Sydney Institute of
Marine Science and the University of Sydney School of Geosciences
have been meeting regularly to explore the possibility of making
low-lying clouds off the northeastern coast of Australia more
reflective in order to cool the waters surrounding the world’s
biggest coral reef system.
During the last two years, the Great Barrier Reef has been
devastated by wide-scale bleaching, which occurs as warm ocean
waters cause corals to discharge the algae that live in symbiosis
with them. Last year, as El Niño events cranked up ocean
temperatures, at least 20 percent of the reef died and more than
90 percent of it was damaged.
The Australian researchers took a hard look at a number
<https://www.theguardian.com/environment/2017/apr/07/plan-cold-water-barrier-reef-stop-bleaching>
of
potential ways
<http://www.newyorker.com/magazine/2016/04/18/a-radical-attempt-to-save-the-reefs-and-forests>
to
preserve the reefs. But at this point, making clouds more
reflective looks like the most feasible way to protect an
ecosystem that stretches across more than 130,000 square miles,
says Daniel Harrison, a postdoctoral research associate with the
Ocean Technology Group at the University of Sydney. “Cloud
brightening is the only thing we’ve identified that’s scalable,
sensible, and relatively environmentally benign,” he says.
Bleached corals on the Great Barrier Reef.
ED ROBERTS/TETHYS IMAGES | ARC CENTRE OF EXCELLENCE CORAL REEF
STUDIES
They’re one of several research groups that have started to
explore whether cloud brightening, generally discussed as a
potential tool to alter the climate as a whole, could be applied
in more targeted ways. All the scientists involved stress that
the research is in its infancy. No one has tested a system for
cloud brightening at all, much less in geographically focused
applications.
British scientist John Latham first proposed the idea as a
potential way of controlling global warming
<http://www.nature.com/nature/journal/v347/n6291/abs/347339b0.html> in
/Nature/ nearly 30 years ago. The theory is that fleets of ships
could spray tiny salt particles, generated from sea water, toward
the low-lying marine clouds that hug the coasts of several
continents. That would provide the nuclei needed to induce
additional droplet formation, expanding the total surface area of
the clouds. The resulting dense, white clouds should reflect more
heat back into space. A 2012 study led by Latham at the
University of Manchester found that the approach could offset the
heating that would result if carbon dioxide doubled in
<http://rsta.royalsocietypublishing.org/content/370/1974/4217> the
atmosphere.
The Marine Cloud Brightening Project, a collaboration between a
group of Silicon Valley researchers
<http://www.sfgate.com/science/article/Looking-to-sky-to-fight-climate-change-4170475.php>
and
University of Washington climate scientists, has done the most
advanced work on the idea to date. The team in Sunnyvale,
California, has spent the last seven years developing a nozzle
that they believe can spray salt particles of just the right size
and quantity to alter the clouds. They’re attempting to raise
several million dollars to build full-scale sprayers, in hopes of
eventually conducting small-scale field trials at some flat point
along the Pacific coastline—ideally a place with onshore winds,
low-lying clouds, and open-minded neighbors.
The Marine Cloud Brightening Project's nozzle sprays a fine mist
of tiny salt particles.
JAMES TEMPLE
They’re among a handful of researchers looking to conduct limited
outdoor experiments to explore the feasibility and risks of such
approaches (see “The Growing Case for Geoengineering
<https://www.technologyreview.com/s/604081/the-growing-case-for-geoengineering/?set=604205>”).
But while the prospect of using geoengineering to ease global
warming on a large scale poses intractable governance issues,
using the technology to address a more localized problem could be
more feasible, at least politically.
Coral reefs are crucial parts of the ocean ecosystem, providing
hunting grounds and homes for thousands of species. They also
generate nearly $200 billion in economic value annually, through
tourism, fisheries, and other activity, according to one study
<https://www.eurekalert.org/pub_releases/2009-10/d-wac101509.php>.
Reefs, however, have been hard hit worldwide by ocean
acidification, pollution, overfishing, and other environmental
stresses. The Great Barrier Reef has shrunk dramatically during
the last three decades
<http://www.bbc.com/news/science-environment-19800253>.
That makes it increasingly urgent to seriously explore ways of
preserving the reefs, even “fairly out-there, grand schemes,”
Harrison says. Next month, he plans to start computer climate
modeling to explore
<http://myerfoundation.org.au/news/2017-myer-innovation-fellows-announced/>
whether
cloud brightening could make a big enough temperature difference
to help. The group plans to collaborate on the research with the
Marine Cloud Brightening Project team.
Should scientists try to save the Great Barrier Reef by
brightening the clouds?
Tell us what you think.
<https://www.technologyreview.com/s/604211/scientists-consider-brighter-clouds-to-preserve-the-great-barrier-reef/#comments>
Coral reefs aren’t the only ecosystem that some scientists
believe might need help from geoengineering. Researchers at the
University of California, the Carnegie Institution, Stanford
University, and Oregon State University have begun a larger
project <http://www.fogsci.com/> exploring, among other things,
how climate change is affecting or will affect the last remaining
stands of coast redwoods.
They're the world's tallest trees, and rely on coastal fog for
around half of their moisture. But Northern California fog levels
have dropped more than 30 percent
<http://www.pnas.org/content/107/10/4533.full> since the early
20th century, a decline linked to urbanization and climate
change. The impact has been limited to date, but fear is growing
that these old-growth stands could be wiped
out if the trends accelerate.
Elliott Campbell, an associate professor of environmental
engineering at UC Merced, says the group has held early talks
with the Marine Cloud Brightening Project about whether the
technique could generate more low-lying clouds to help feed
moisture to the redwoods. “If we could artificially produce fog
on summer mornings, and that could help us buy the redwoods more
time as we shift to a less carbon-intensive economy, that’s
potentially a good thing,” Campbell says.
Aerial view of a bleached portion of the Great Barrier Reef.
ARC CENTRE OF EXCELLENCE CORAL REEF STUDIES
Ken Caldeira
<https://www.technologyreview.com/s/543916/stop-emissions/>, a
prominent climate scientist at the Carnegie Institution who has
modeled the potential of cloud brightening, says the idea of
localized geoengineering is worth exploring. But he’s not
convinced that cloud brightening could produce a substantial
climate effect at such a limited level. Below a certain
geographic footprint, probably around 10,000 square miles, it
might be difficult to produce a big enough change in cloud
density to add up to much of a difference, he says. He’s
specifically skeptical that it would work at the Great Barrier Reef.
“I just don’t think there are enough clouds of the right type
there that would be susceptible to marine cloud brightening,” he
says.
The University of Sydney’s Harrison is aware of the concerns
Caldeira raises and intends to look at these issues closely in
his feasibility research. But at a first pass, he believes there
could be sufficient marine clouds to help preserve the Great
Barrier Reef.
In any case, he hopes so, because nothing else looks particularly
promising.
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Tagged
Ken Caldeira
<https://www.technologyreview.com/g/ken-caldeira/>,geoengineering
<https://www.technologyreview.com/g/geoengineering/>, clouds
<https://www.technologyreview.com/g/clouds/>,Great Barrier Reef
<https://www.technologyreview.com/g/great-barrier-reef/>, Daniel
Harrison <https://www.technologyreview.com/g/daniel-harrison/>,
Australia <https://www.technologyreview.com/g/australia/>
James Temple
James Temple
<https://www.technologyreview.com/profile/james-temple/>Senior
Editor, Energy
I am the senior editor for energy at /MIT Technology Review/. I’m
focused on renewable energy and the use of technology to combat
climate change. Previously, I was a senior director at the
/Verge/, deputy managing editor at /Recode/, and columnist at the
/San Francisco Chronicle/. When I’m not writing about energy and
climate change, I’m often hiking with my dog or shooting video of
California landscapes.
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