Anoop K. Menon
From the windows of our 20th floor office, the Arabian Gulf is clearly visible. Its waters are calm, benign, inviting and often colourful; it is also a view that me, you and many others have now taken for granted. But the Arabian Gulf is more than just a great view. It is an inescapable part of our daily life too. It is the main source of water (obtained through desalination) for many countries at its periphery. There is an economic dimension too as the Gulf is a vital oil & gas transport route, accounting for almost one third of the world’s oil exports and approximately 18% of gas shipments.
However, all over the world, the mighty oceans and seas are changing, probably for the worse. The following snippets explain why. According to a report by European Science Foundation, a combination of ocean acidification and global warming may be the most critical environmental and economic challenge of the century. For long, oceans have buffered the effects of global warming by absorbing almost a third of the CO2 emitted from fossil fuel use. In fact, the Global Carbon Project notes that the global oceanic CO2 sink removed 26% of all CO2 emissions for the period 2000-2008. Today the oceans are more acidic than they have ever been for at least 20 million years. This chemical change could cause significant consequences to marine ecosystems and the goods and services that they provide.
The European report points out that a business-as-usual scenario will result in the ocean becoming 150% more acidic by the end of this century. A study by Livermore National Laboratory noted that the projected increases in CO2 in the atmosphere may drive ocean pH values, the scale for measuring acidity, to change more rapidly than at any time over the last 25 million years. A reduction in the capacity of this carbon sink would result in a larger CO2 mitigation requirement to control climate change.
Integrated research on the impacts of ocean acidification is still a very new field – the full implications of these changes are unclear for marine ecosystems and fisheries resources. One area that has received attention is the impact of ocean acidification on calcifying organisms like corals and shell fish. For example, corals extract dissolved calcium carbonate from seawater to make their external skeletons. As water becomes more acidic, the concentration of calcium carbonate falls, and eventually there is so little that skeletons cannot form. Thus ocean acidification can impact the marine food chain.
Ocean currents serve as an important mode of heat transfer, helping the earth to balance heat. Scientists feel that this huge conveyor mechanism is now slowing down. Since the heat has to move, they are predicting more frequent storms and cyclones.
Half of the increase in sea level – rising at a rate of 3.2-mm per year – is due to the expansion of the ocean which traps the heat and gets warmer. The Intergovernmental Panel on Climate Change predicts that the rate of rise may approach five to eight millimetres per year by 2100. The latest model for sea level rise incorporates the Earth’s Albedo. As the ice and snow melts in the Arctic and the Antarctic, the Earth’s Albedo is changing from a reflective surface which reflects most of the sun light back up to an absorptive one, because the exposed brown mud and blue oceans absorb the heat. A decrease in Albedo means more energy is absorbed which causes further warming and more melting. A positive feedback loop is formed which then speeds up the change in global temperature.
The relationship between the climate and ocean is a dynamic one. Understanding how the carbon cycle works with regard to the ocean is important to predicting future climate change.
Anoop K. Menon
