Studies seem to indicate that oceans, which are major carbon sinks, may have had enough. If so, the consequences are BAD, writes Jayalakshmi K.

Ocean deserts, which are non-productive areas, have increased by 15 per cent in the period 1998-2007, according to a study done by the National Oceanic and Atmospheric Administration (NOAA) in the US and the University of Hawaii. This translates into a total of 6.6 million sq km. On the whole, there are 51 million sq km of such desert zones. The data was collected by Nasa's orbiting SeaStar craft.

Attributed mostly to warming surface waters, which is happening at a rate of 1 per cent every year, this creates many layers in the ocean waters, preventing deep ocean nutrients from rising to the surface and feeding plant life.

These areas are found in roughly 20 per cent of the world's oceans and are within subtropical regions on either side of the equator. Whether it is due to natural reasons or man-induced is not known. But, as the study says, it means more loss of marine life.

Half of the carbon dioxide released ends up in the oceans, which in the last 200 years alone amounts to 500 billion tons. So far the acidity of the oceans due to this carbon content has been constant. But now, the acidity may be up by 0.1 of a pH unit.

While the figure seems small, it translates to a pH figure lower than in millions of years and a rate of change 100 times greater than ever. The Lawrence Livermore National Lab study suggests that even if emissions are stopped, acidification would continue. The carbon dioxide in the air will further add up to 0.5 of pH.
Ocean acidity has been largely stable at a pH of 8.2. While the chemical equilibrium managed to keep things that way, now the geological processes are unable to keep pace with the way carbon dioxide is increasing. As a result, acidity has been affected.

Changes in acidity will affect animals like corals, mollusks and plankton that use calcium carbonate to make their shells. A NERC study (UK) looked at how phytoplanktons, which provide nutrients for plant life in the oceans, are affected by increasing acidity. For instance, sea urchins that release nutrients from the seabed for the planktons were shown to be affected by the acidity, both in their carbonate skeleton and internal organs.

Yet another study, the Global Carbon Project, shows that the natural systems are giving up! In terms of removing the greenhouse gases in the atmosphere. This means both land with its carbon sinks in the green patches and the oceans. Since 2000, the atmospheric carbon dioxide has increased 35 per cent faster than expected!
It does not need much imagination to see how the web of life can be damaged, beginning with sea urchins to planktons to marine life that refuses to take up anymore carbon dioxide. From there to a runaway greenhouse effect that turned Venus into a sizzling landscape could be the doing of a mere hundred years!

As Prof J Srinivasan, CAOS, IISc, notes, not many realise the damage to the oceans and that is not only from global warming. Acidification is taking a toll on marine life. Besides the carbon emissions, there is the damage from all the fertiliser run off too.

The warning bells have not stopped ringing. The effects of a hot planet too are being experienced. But action has not started on the urgent footing required. Why? Why, when the technology is all there? Political will or public apathy? Do we really need calamities to jerk us out of inaction?

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