The Food and Agriculture Organisation has issued a caution on the repercussions of climate change on fisheries and aquaculture. It is that the changes seen in the seas and oceans will have direct implications for food security. This is particularly relevant to developing countries where about 42 million people work directly in the sector and 2.8 billion depend on fish products for 20 per cent of animal protein. Although the impact of higher temperatures is more pronounced in certain geographical locations and more intense in surface waters, studies have confirmed that warming of the oceans can go deeper than 700 metres. This is ominous. Any further heating of the ocean water, which acts as a sink by storing more than 90 per cent of the earth’s heat, can result in some tipping points being crossed, which means the environment can be affected in some major ways. The warming of surface water has already led to changes in species composition in the northern hemisphere — warm-water species replacing coldwater fishes, ice-bound regions being invaded by aquatic species, and freshwater species taking the place of marine species. The warming has also led to algae blooms in the hostile northern hemisphere oceans, raising alarm signals for the survival of fish. The change in the ocean salinity and acidity is also affecting fisheries and aquaculture.
According to the 4th Assessment Report of the Intergovernmental Panel for Climate Change (IPCC), for the next two decades a warming of about 0.2 degree Celsius per decade is projected for a range of emission scenarios. There is emerging evidence that marine organisms are responding faster to global warming than previously thought. The Marine Climate Change Impacts Partnership report card 2007-08 has highlighted the way U.K marine wildlife has begun to suffer as a result of wetter and warmer winters. It is difficult to predict what further changes the warming will bring. According to the FAO, climate change “will increase uncertainties in the supply of fish,” which in turn will make risk assessment more challenging. Owing to changes in fish species, the impact of climate change will mainly be felt in the availability of, and access to, food. Already the United States and Canada are negotiating access to certain fish species whose spatial distributions are determined by environmental variations. By far the major contributor of aquaculture, Asia will be the most vulnerable region. All this suggests that cutting emissions has become more urgent than ever — which, unfortunately, is something the recent G-8 Summit in Japan failed to agree upon.