Oceans Could Lose $1 Trillion in Value Due to Acidification

http://www.scientificamerican.com/article/oceans-could-lose-1-trillion-in-value-due-to-acidification/?WT.mc_id=SA_ENGYSUS_20141023

Oct. 21, 2014

Biological Diversity released a report updating the impacts of ocean acidification on marine life. This time, it put estimated costs on the predicted damage, hoping to make governments aware of the potential size of the various threats.

While many of the effects of growing acidification remain invisible, by the end of this century, things will have changed drastically, the report found. One estimate looking only at lost ecosystem protections, such as that provided by tropical reefs, cited an economic value of $1 trillion annually.

Over the last 200 years, the world's oceans have absorbed more than a quarter of the carbon dioxide released by humans, becoming 26 percent more acidic. Though technically waters have not yet become acidic, according to the pH scale, the report found this could occur by 2100 if emissions continue to rise.

•••••

Ocean acidification, first discussed in the 1990s, didn't become a well-documented trend until 2004. But since then, the number of researchers entering the field has grown substantially. From 2004 to 2013, the report found, studies published on the topic grew twentyfold.

"This alone warranted an update to the report," said Roberts.

But it wasn't the only factor; the whole scope of the 2009 study needed to be altered to reflect reality, he explained.

"In 2009, we didn't take into consideration societal implications, loss of ecosystem services or policy at all," said Roberts. "But by just looking at an example such as tropical reefs, it's clear destruction of these reefs can lead to decreased food security, income loss, shoreline damage and much more."

•••••

Of the 400 million people cited to live within 62 miles of tropical reefs, many rely on these fish habitats for their livelihoods and a vast majority of their protein intake. So negative impacts on reefs represent a direct threat to human populations, explained Roberts.

•••••

Additional factors beyond the ability to function under decreased pH, like habitat loss and behavioral changes, he said, may present even more immediate threats to marine species. At lower pH levels, many fish loose their ability to understand chemical cues that help them learn their environment and avoid predators.

Fish that lose their sense of predators "also expose themselves to further risk exhibiting bold behavior in the search for more food to meet their new energetic demands," he explained. "These kind of findings could have never been anticipated; we found them by virtue of asking seemingly unrelated questions."

•••••

The last time the Earth's oceans experienced these kinds of carbon dioxide changes, the report found, was 56 million years ago, during the Paleo-Eocene Thermal Maximum, or PETM, when 2,000 to 3,000 petagrams of CO2 was released over 10,000 years.

The results killed a vast abundance of marine life, primarily calcifiers. Then it took the oceans roughly 100,000 years to rebalance. By comparison, today's changes are occurring at 10 times this rate, with projections of PETM levels by 2600 if emission levels remain the same.