CO2 Levels, Oceans and Fisheries
Most of us are familiar with the idea of carbon dioxide (CO2) from industrial development leaching into the atmosphere, causing global warming. The effect of CO2 on ocean temperatures and acidification is much less well publicised, but just as worrying. In fact, it’s a potential cause of famine.
Oceans soak up CO2
Globally, the ocean surface has probably taken up around one third of the carbon emissions that have been created since the Industrial Revolution – while this is great news in that it’s reduced the greenhouse gasses in the atmosphere, it’s had a range of effects on oceanic chemistry and biology that are much less comforting.
The absorption of carbon dioxide results in a change in oceanic pH – the oceans are becoming more acid – and this acidification, amongst other effects, means that the carbonates that shellfish require to create strong shells are less available. These carbonate ions feature not only in shells, but in the creation of coral reefs and as part of the food source for much larger fish.
The world’s favourite fish need less acidic oceans
If acidification continues at the rates projected by the Intergovernmental Panel on Climate Change, we could see ocean acidification affect tourism, as coral reefs cease to grow and may actually contract, and food security, as commercially popular shellfish species either decline or become malformed and unattractive to consumers. The effects may move up the food chain quite fast – pteropods are simple sea snails and their shells are formed out of aragonite, which is likely to be the form of calcium carbonate most at risk from acidification. While pteropods might not appear on your dining table (or anybody’s dining table, being lentil-sized free-floating creatures) they are an important food source for young salmon, pollock and cod – species which are essential to the economics of fisheries around the world.
And while the developed world can simply chose to eat different fish, from different places, the protein provided by fishing is essential to around one third of the world’s population and, for most of them, there is no choice – fish and shellfish caught by artisanal fishermen or harvested by women along the sea shore are their primary and often their only source of complete protein. If acidification reduces the quantity, quality or location of fish and shellfish, they will have nothing with which to replace them.
Managing ocean acidification
Preserving the viability of the complex ecosystems of the oceans requires us to take action on CO2 emissions – at the beginning of the Industrial Age, atmospheric CO2 concentrations were around 280 parts per million – today they have reached 388 parts per million and if they exceed 550 parts per million, tropical corals will not be able to grow and simple organisms like pteropods may not find enough carbonate ions in the oceans to create their shells.
Current plans for cutting CO2, if carried out effectively, will probably leaves us with a CO2 level of 550 parts per million – exactly the level which could tip the oceans into unproductive acid levels. And while we have understanding of atmospheric CO2 and we’re able to monitor the relatively simple effects it has and even, to a certain extent to rectify those effects, the complex effects of ocean acidification are difficult to understand, almost impossible to monitor globally, and rectification plans are much less developed than for the atmosphere.
Drying cod courtesy of g.nordoy at Flickr under a creative commons licence
The politically correct admonistion to reduce emissions is fine but it will NOT help save the oceans from CO2. The more than 1000 billion tonnes of CO2 already spewed into the air over the course of the fossil fuel age to date is only 1/4 absorbed by land and sea, mostly sea. The remaining payload of this first carbon bomb is more than sufficient to sel the doom of the oceans as we know them and not only from acidification. The more deadly effect of high CO2 is that if helps plants on land be better ground cover keeping dust from blowing in the wind and to the oceans where it is the most vital of ocean plant nutrients. 12% of the ocean plants have disappeared from the Southern Ocean in just the past 30 years, the number is 17% in the North Atlantic, 26% in te North Pacific, and 50% is some tropical seas.
Even if we stop all emissions today the remaining deadly first carbon bomb will change the oceans into seas of bacterial slime. This change will be sealed by the year 2030 if we do nothing to replenish and restore the oceans. By replenishing natural dust to the oceans the ocean plants will be restored and as they did just 30 years ago convert 4-5 billion tonnes of toxic CO2 into life instead of acid death.
Replenish the vital mineral dust, restore the oceans and be successful before 2030. That is what is required of us to undo the wrong of yesterdays CO2. Todays and tomorrows CO2 will be meaningless if we do nothing about yesterdays.
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