The increasing buildup of carbon dioxide in the atmosphere is reshaping the environment in many ways beyond the ongoing rise of global temperatures. Some major ones relate to the ocean, which is becoming not just warmer but also more acidic, threatening to degrade the world's coral reefs. Researchers have put forward an interesting way of preventing some of this damage, through a study demonstrating how releasing an alkalinizing agent from shipping lanes could protect much of Australia's Great Barrier Reef.
More acidic waters with lower pH levels pose a threat to coral reefs by reducing concentrations of carbonate ions in the seawater, which form part of the calcium carbonates reefs use to build out their skeletons. This in turn compromises the reef's ability to form structures and repair themselves following bleaching events, like the severe ones that have devastated the Great Barrier Reef in recent years.
Adding artificial sources of alkalinity to the seawater is one way of rebalancing the pH levels, though doing so in a way that could have a meaningful impact on coral reefs would be a huge undertaking. Scientists at Australia's Commonwealth Scientific and Industrial Research Organisation have, however, explored the possibility of undertaking this approach on a scale not yet considered.
"The majority of the artificial ocean alkalinization modeling studies to date have focused on the potential for alkalinization as a carbon dioxide removal technique," the team writes in its paper. "Few studies have explored the role of alkalinization with a focus on offsetting the changes associated with ocean acidification at a regional scale.”
To do this, the researchers used what they call a coupled hydrodynamic-biogeochemical model, which was developed recently and validated for the Great Barrier Reef region. This enabled them to simulate the effects of releasing 30,000 tons of alkalinizing agent from a carrier along an existing shipping lane, which they found would result in artificial ocean alkalinization reaching almost the entire reef, stretching across more than 2,000 km (1,430 miles).
According to the authors, this strategy would offset 10 years' worth of ocean acidification in the area, while also sequestering 35,000 tons of carbon dioxide per year, as more alkalinity in the ocean improves its ability to absorb CO2 from the air.
The study offers another interesting pathway through which scientists may be able to protect coral reefs. Some other interesting examples include underwater speakers that lure fish in to help restore them, floating films that protect them from harsh UV light, and raising turbo-charged coral babies and implanting them degraded areas. Rather than permanent solutions, it must be noted, these are seen as ways of buying time and reinforcing vulnerable areas while we address the broader issues of climate change and its effects on the oceans.
The study was in the journal Environmental Research Letters.
Source: IOP Publishing