State of the world’s oceans getting critical.
The International programme on the State of the Oceans released a grim report this week quantifying the threats to the marine ecosystems upon which we all depend (as they do every 2 years), and underlining in particular that the rate of acidification due to anthropogenic carbon emissions is at its highest in 300 million years. Billions of people worldwide depend on the sea for their protein, and many more jobs depend on tourism in coral areas for example.
This imperils many organisms, from corals and shelled animals (such as mussels or oysters) to plankton (the base of all marine food chains), which secrete calcium carbonate shells that are dissolved by the weak carbonic acid produced by the interaction of CO2 and water that also produces Earth’s beautiful karst landscapes and limestone cave systems (for an explanatory post focussed on the Arctic Ocean see http://tinyurl.com/q5e4ywz).
Other major threats mentioned include chemical pollution, overfishing, spreading marine deserts, coral loss and lowered oxygen levels (on which most marine life depends for breathing). They conclude that the state of the oceans is reaching a critical point where a mass extinction of marine species, particularly those at threat from acidification, may be inevitable. An unknown territory of ecosystem change has reached the point where ecosystems are under possibly intolerable strain.
To quote Alex Rogers, a professor of biology at Oxford University: “The health of the ocean is spiralling downwards far more rapidly than we had thought. We are seeing greater change, happening faster, and the effects are more imminent than previously anticipated. The situation should be of the gravest concern to everyone since everyone will be affected by changes in the ability of the ocean to support life on Earth.” Trevor Manuel, a South African government minister and co-chair of the Global Ocean Commission, called the report “a deafening alarm bell on humanity’s wider impacts on the global oceans”.
Much of the CO2 we emit and most of the resulting heat are absorbed by the oceans, which has shielded us so far from the full effects of climate change. Should their ability to do so change, for example by becoming closer to saturation with CO2, then we will lose the buffer that is keeping the effects of our pollution from being overwhelming obvious, and all the energy accumulated by global warming will start to be felt on land.
Current rates of ocean absorption are estimated at 10 times faster than during the last mass extinction, probably triggered by release of methane clathrates, known as the Paleocene Eocene thermal maximum. The world took 100,000 years to recover from it (see http://tinyurl.com/povhewl and http://tinyurl.com/qfqtkc4).
Marine deserts are also spreading, mostly due to algal blooms de-oxygenating the water after being fed by fertiliser and sewage runoff from rivers.
The results were also published in the peer reviewed Marine Pollution Bulletin. It is time that our actions start to be perceived as a major threat worldwide to national, and indeed human, security, and treated as a clear and imminent danger. If enough phytoplankton die off, our own oxygen supply is at risk, since they produce 40% of the atmosphere’s oxygen. An urgent and deep reduction in fossil fuel use is the main thing we can do to help avert the coming crisis.
Image credit: Varulvsnatt