Ocean Acidification

Ocean acidification has widely become labelled as “the evil twin of climate change”. Recent research indicates that our oceans are becoming steadily more acidic as a direct consequence of sea water reacting with the increased amounts of carbon dioxide (CO2) emissions being released in to the atmosphere from manmade activities.[1]

The relative consistency of our oceans’ acidity levels have allowed a rich underwater world to flourish over tens of millions of years. This is now being threatened by the billions of tons of greenhouse gases that have been emitted into the atmosphere since the onset of the industrial revolution in the 1800s [2]. The atmospheric concentration of CO2 has risen from 280 parts per million to over 394 parts per million. This increase is largely due to the burning of fossil fuels and deforestation. Annually our oceans absorb more than 25% of our human-induced CO2 emissions.[3]

The Ocean Acidification International Coordination Centre believes that the current rate of acidification is unparalleled in the earth’s history, with estimates stating the speed of our decreasing pH levels to be 10 to 100 times faster than at any other time in the past 50 million years. We are currently experiencing a drop from a relatively consistent pH level of 8.2 to 8.1. Based on these findings scientists predict that these pH levels will continue to drop to 7.8–7.9 by 2100.[4]

The impact of emissions on our oceans

graph_impactOnOceans

Credit: Adapted from Bopp et al., 2013. Ocean surface pH projections to 2100.

What are the effects?

The adverse effects of ocean acidification are already becoming apparent with experts envisaging that at this continued rate of acidification the entire web of life below the water surface will experience devastating ramifications in the future. For many marine organisms, changes in pH and carbonate chemistry levels force them to expend more energy regulating their cell chemistry, resulting in a reduced amount of energy available for growth and reproduction.

It is feared that we will see changes in the number and abundance of marine organisms, with potentially different and less varied species occupying our sea waters. This will have a disruptive impact upon entire food chains, as well as community dynamics, biodiversity, and ecosystem structures. These fears are not unfounded. During an acidification event known as the Paleocene-Eocene Thermal Maximum, which occurred 55 million years ago, there was a mass extinction of some marine species.[5]

It is of course not only our marine life that will feel the damaging consequences of ocean acidification. Warm water corals for example reduce the rate of coastal erosion, and have become an important source of tourism and income. An estimated 500 million people depend on coral reefs for their food and livelihoods, with the Great Barrier Reef alone generating over 6.5 billion dollars (AUD) in tourism revenue a year. Coral reefs are also home to at least a quarter of all marine species. However, our reefs are becoming increasingly deteriorated as rising acidification is preventing them from absorbing the amount of calcium carbonate required to maintain their stony skeletons. In addition, coral is extremely sensitive to the rising water temperatures associated with manmade climate change and reacts by expelling its’ symbiotic algae, zooxanthellae, which is critical for a reef’s survival as it provides 80% of its energy. As the algae leaves, the coral becomes pale in colour; this is known as “coral bleaching”.[6]

Bleached coralRising sea temperatures cause corals to bleach and die, break up and become rubble. On this reef there is some regrowth of young corals so there is hope for recovery.
Half dead coralHealthy and dead parts of the same coral.

What action can be taken?

According to scientists, full recovery of the state of our oceans is not possible in the next tens to hundreds of millennia. Even geo-engineering proposals to cool the planet will not reduce ocean acidification as they do not tackle the main cause; the global amount of excess greenhouse gases still being emitted into the atmosphere. According to the World Wildlife Fund, 25% of our coral reefs have been irreversibly damaged.[4]

We need to work now to reduce global CO2 emissions significantly, whilst striving to moderate current issues and prevent further environmental stresses which heighten the effects of acidification, such as overfishing, pollution, nutrient loadings and eutrophication (when the environment becomes enriched with nutrients).[5]

Although scientific understanding of the damaging effects of ocean acidification upon marine ecosystems could be considered a relatively recent revelation, it remains clear that unless we drastically limit, and eventually eliminate, our fossil fuel emissions, marine organisms will find themselves increasingly pressured to adapt to their rapidly altering habitat, or risk extinction.

One crucial way of reducing fossil fuel emissions is to tackle vehicle greenhouse gas production. The U.S. Environmental Production Agency for example, estimates that on average a typical passenger vehicle alone emits 5.1 metric tons of carbon dioxide per year[7]. This is why Gazasia is committed to improving air quality and mitigating greenhouse gas emissions by producing biomethane, a clean and renewable road transport fuel. Compared to diesel, biomethane is a very clean burning fuel offering more than 90% reduction in particulate matter emissions, over 60% reduction in nitrogen oxides, and 50% reduction in sulphur dioxide emissions. Further-more, biomethane is a carbon neutral fuel achieving over a 100% reduction in lifecycle greenhouse gas emissions compared to diesel.

 

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