Environment

Stepping back in time to protect the future of the Great Barrier Reef

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In 100 years, the Great Barrier Reef could look very different to the way it does today
Coral along the reef edge in One Tree Island's lagoon
Ken Caldeira
The pink, conditioned seawater solution being pumped onto the reef flat
Rebecca Albright
The yellow tank (right) is where the scientists manipulated seawater to reach pre-industrial levels before pumping onto the reef flat study site
Ken Caldeira
Kennedy Wolfe collecting water samples on the experimental reef flat
Ken Caldeira
In 100 years, the Great Barrier Reef could look very different to the way it does today
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Australia's stunning Great Barrier Reef is changing, and not for the better. In the years since the industrial revolution, the increasing amount of carbon dioxide in the atmosphere has made the oceans warmer and also more acidic, which is bad news if you're young coral trying to make your way in the world. In the first study of its kind, a team of scientists has altered the seawater chemistry in a natural section of the reef to mimic pre-industrial conditions, observing just how well the coral was able to grow before we came along and altered the landscape. Gizmag spoke with one of the researchers involved to learn how stepping back in time might make for smarter steps into the future.

Covering an area almost half the size of Texas, the Great Barrier Reef is home to around 600 types of coral. Here, just like other reef systems around the world, the hard, stone-like corals build out their skeletons by drawing calcium carbonate minerals from the seawater. But due to human activity, the availability of these minerals is coming under threat.

Scientists estimate that around one quarter of the excess carbon dioxide we pump into the atmosphere is absorbed by the ocean. This triggers chemical reactions that boost the acidity of the seawater, dissolving the vital calcium carbonates that provide the building blocks of not just these coral reefs, but the skeletons and shells of other marine organisms too.

That ocean acidification has this effect on coral reef systems is well documented, with previous studies carried out in laboratories or closed-system tanks showing that rising acidity is making life more difficult for corals. But for the first time, a team of researchers has now taken the science into the field, manipulating the water flowing over a natural reef flat to gain a clearer understanding of how ocean acidification is impacting natural coral calcification.

The pink, conditioned seawater solution being pumped onto the reef flat
Rebecca Albright

"We ran the experiment over several years, doing intensive field work and took measurements each day that we were on the reef," Kennedy Wolfe, PhD candidate at the University of Sydney, tells Gizmag. "The experiments were conduced on One Tree Island, which provided a very unique habitat, where we recreated the ocean conditions estimated for around 200 years ago. Our treatment was based on previous studies of atmospheric carbon dioxide throughout history."

One Tree Island sits toward the southern end of the Great Barrier Reef and presents an almost pristine natural lagoon with limited human impact, offering an ideal outdoor laboratory to carry out studies on natural ecosystems.

"This exposed reef made it quite easy to work on a specific problem," explains Wolfe. "We deployed a 15,000 L (3,962 gal) tank, which we scooped water into and added sodium hydroxide to reduce the acidity to pre-industrial levels. We then pumped the conditioned water onto the reef and took water samples to calculate the coral's uptake of calcium carbonate minerals. We were able to determine that calcification increased by around seven percent under pre-industrial conditions."

Kennedy Wolfe collecting water samples on the experimental reef flat
Ken Caldeira

While it is difficult to estimate exactly how these results translate to the wider Great Barrier Reef, let alone to other reef systems with different tolerances in other parts of the world, they do show that man-made ocean acidification is already having an impact on coral growth. And according to some, unchecked carbon emissions could soon lead to a tipping point where ocean acidity causes reefs to switch from productive calcification to destructive dissolution. While troubled by this, Wolfe reasons that it is not all doom and gloom.

"Many have estimated that reefs will go from calcification to dissolution some time this century, which is quite concerning," says Wolfe. "Studies on this, however, fail to understand that there is always the ability of organisms to adapt. There are organisms that have evolved and adapted through ice ages and through huge shifts in weather patterns.

"There is research that does look into this adaptation, but it is only recently coming to light as these generational studies take a lot of time," he continues. "Certain species are going to be winners, while some will be losers. The Great Barrier Reef might still exist in 100 years despite net dissolution, but it will definitely look different to the reef we know today."

Coral along the reef edge in One Tree Island's lagoon
Ken Caldeira

Rising acidity is of course just one piece of the puzzle when assessing the impact of climate change on the future of coral systems. Warming oceans, for example, present a similarly ominous threat. Increases in water temperature affect the algae living inside the coral tissue that provides them with food. This extra heat stress on the algae leads to coral bleaching and death, and though other factors can trigger bleaching events, their frequency and severity is expected to increase in line with rising ocean temperatures.

"We've seen major bleaching events on the Great Barrier Reef this year," says Wolfe. "But the real concern is that over the coming decades warmer waters will combine with acidifying oceans and things like overfishing, pollution and destructive tourism. It's when all these stressors occur in synergy that they will pose an irreversible threat to the reef."

Such factors are obviously cause for concern. While things like overfishing and pollution could realistically be reigned in, solving the problem of warming and ocean acification presents an entirely different, and perhaps insurmountable, kind of challenge.

"There has been discussion around some kind of geoengineering approach," says Wolfe. "In our experiment, for example, we added sodium hydroxide to a big bucket to alter the seawater conditions in a localized habitat, and there has been talk of doing something like this on a broader scale.

"But altering the ocean's chemistry in any meaningful way would be very labor-intensive, costly and wouldn't make much sense. The only real, lasting solution we have is to cut carbon emissions. If we keep burning carbon at the exponential rate we are now the effects will only intensify, and that bucket we would be relying on would only have to get bigger and bigger."

The team's study is published in the journal Nature.

View gallery - 5 images
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6 comments
ezeflyer
Bernie is the only candidate that would tax carbon emissions, the only way to reduce these in time to prevent the death of our oceans.
David A Galler
The Great Barrier Reef is very large and has been on Earth during periods of much greater CO2.
Lbrewer42
Bad on many accounts: 1. The actual science is that CO2 is NOT ADDED to a greenhouse to make the temperature inside rise. CO2 does NOT hold in heat. 2. THe only CO2 in a greenhouse is used up by photosynthesis (remember - no EXTRA is added) - and the resulting water vapor is what holds in the heat.
This IS the actual science. CO2 is NOT a greenhouse gas. But, those in power could not easily make money off of the truth. They could not very well make us believe we have to have emissions checks in vehicles for giving off water vapor now could they?
3. Since Biosphere II proved we do NOT have the technology to make a viable ocean environment, they are going to now submit the already deteriorating Great Barrier Reef to our flawed perception of how the perfect aquatic environment would be maintained?!
4. We do not KNOW how the pre-industrial environment would have been considering historic warming trends before the Industrial Revolution were not uncommon and sometimes warmer than what the alleged farce of AGW proposes - they used to farm Greenland in areas that are now covered in glacier.
But please, don't believe any of this... look up the scientific facts posted for yourself, and let;s hope they don;t mess up the Great Barrier Reef based on a political, moneyt-making lie.
And one more powerful hit... Google "Game Over, The IPCC Quietly admits Defeat." The data from the UN's International Panel on Climate Change was compiled and proved to them AGW had not been happening for at least the last 15 years. The UN even took a vote as to what to do now. They concluded to keep up with the regulations etc. (no surprise here - power is addicting) in case it MIGHT happen.
MQ
Lbrewer42. You have a little error on your "diatribe" Greenhouses DO ADD C02 top their atmosphere.
You are correct they do not do it to increase the temperature, the glass, water vapour, controlled ventilation and gas-water heaters do that for them. They add the C02 to increase the plant growth rate.
It is not uncommon in some parts for a C02 level in Exceess of 1500 ppm, triple the atmospheric amount. The workers in these greenhouses are not "poisoned" by these amounts, and the plants benefit greatly.
Taxing the very air that we breathe, used to be a statement illustrating the stifling effect of big government, well it has happened and continues in some nations.
Government talks big, but offed "offsets" to anyone who is impacted by the tax from power generators to consumers, so where was the bebefit of the tax (scrapped here).
I'm all for efficient use of resources (resource wise, and economically), and when the possibility exists to effectively use the natural resources in the form of sun wind and wave, the downsides are less than that of (world-wide) widespread use of nuclear and coal fired powerstations. There will be some place in the mix for most forms of generation, but we have to be smart and allow the developing world to transition in a way that is least harmful to their own existence and transition our own world to a lower pollution society, we all need to breathe clean air and drink clean water.
Lets save the hydrocarbons (if technically possible) for real value-adding industries rather than just burning them all into a brown haze in miliseconds.
IPCC, do need to include the effect of clouds, (as well as fully model water and gas transport in 4 dimensions) into ALL their models for them to have any meaningful understanding on how the atmosphere affects weather and "climate", I think we are still a long way from "fully" understanding how the natural system operates. Reconstructed historical proxy data uses many assumptions which it is hard to falsify, and even harder to verify.
Rann Xeroxx
This has already been debunked. And further more, the Earth has had higher concentrations of CO2 in the past before.
http://www.c3headlines.com/are-coral-reefs-dying/
Don Duncan
MD: An independent think tank, RMI (Rocky Mountain Institute) has been studying energy needs/usage for over 35 years. It concluded that the solution is a free market in energy, free from govt. manipulation/regulation. Dr. Amory Lovins, with 21 doctorates, has advised multiple industries on nega-watts (conservation) engineering to provide for all energy needs without upsizing. The general rule is: the market, freed from force of bureaucrats, solves all problems.