Climate change, as interpreted by Kingsolver, is a misnomer, implying some singular alterations of the Earth’s physical and biological characteristics. Instead, global change is an assortment of quite diverse changes – climate change, environmental toxins, habitat loss and alteration, invading pests and pathogens, harvesting of natural resources. Of all the thousands of years humans have inhabited this Earth, it has been only last few centuries that the human induced changes have started to have effects more profound that those caused by geological and climate forces that shaped the Earth’s environment over previous thousands of years. Environment being an aggregate of the physical and biological components of the Earth has a complex structure. Any change in one of its factors causes other factors to change so as to maintain equilibrium. It is to this changing equilibrium, the flora and fauna of this Earth have to adjust. Any aberration in one of the factors causes stress to animals not only to that particular changing factor but also to the other factors which might change in response to previously changed factor. In this way an animal or plant is always under the influence of multiple stressors.
Climate change and its impact on food security:
A major part of India’s population is rural and agriculturally oriented, for whom the rivers and agriculture is a source of prosperity (Mall, et al. 2006). Fish is known to be the cheapest source of protein available to mankind. It not only provides high quality, easily digestible protein but also provides with many other nutrients like omega – 3 fatty acids, vitamins, minerals etc. It is well known fact that the human civilization began on the water banks and these banks are still the most densely inhabited regions. Hence, fish naturally becomes an important part of the diet of the large part of the population striving on Earth. Talking of Indian fisheries sector especially, over one million people depend on it for their livelihood. This sector depends and hence the entire population thriving on it depends heavily on the availability of water. Aquatic habitat is not only dependent on the availability of water but also upon various physical, biological and chemical factors like temperature of water, light penetration, oxygen carrying capacity of water, water flow rate, depth, rate of precipitation. Any change in any of these factors will impact the aquatic habitat and will affect the lives of people depending on fisheries. Considering the effect on food security, the impact of climate change will be most on the populations in Indian Ocean zone as this is the region which is most densely populated of all the coasts, with 135 persons per square kilometer (UN world resource index, 1998). Sixty percent of Asian population lives within 400 Km from the coast (Hinrichsen, D. 1999) and 25% of Indian population lives in the coastal regions. It is natural that fish is the main food source for this population and if not, then fisheries is one of the major bread earning sector for them.
One of the most common seen effect of climate change is warming of coastal waters. The waters along the Indian coast have experienced rising waters over the period of time. Sea surface temperature has increased by 0.20C along the northwest, southwest and northeast coast while there has been an increase of 0.30C in the southeast coast of India (Vivekananda et al. 2009) from 1961 – 2005.
Fig. Warming of Indian coast. (Vivekananda et al. 2009).
Due to this rise in temperature there has been decreased monsoon rainfall, frequent and intense cyclones, and warmer winters along the Arabian Sea coast. This not only has affected shift in the fish capture pattern but has also decreased wheat production along this region (Prasannkumar et al. 2009).
Many fish species are already facing the extreme temperatures. Out of many types of responses shown by fish to rising temperature is northward shift. But India’s northern coast is landlocked and there is no scope for fish migrating northwards once they reach the northern limits of Arabian Sea and Bay of Bengal. Till now there has been a positive correlation between rising sea surface temperature (SST) and the Indian oil sardine catch and Indian Mackerel catch which contribute heavily to the Indian Marine capture and is a major protein constituent of India’s western coast but if the temperature keeps on increasing at the same rate then these two species are expected to be driven away from the southern lattitudes and may affect the fishery of off Malabar coast and South Konkan coast (Vivekananda et al. 2009).
During 1985-89, only 2% of mackerel catch was from bottom trawlers, and the rest of the catch was contributed by pelagic gear such as drift gillnet. During 2003-2007, it is estimated that 15% of mackerel catch is contributed by bottom trawlers along the Indian coast. This is correlated to rising SST. Hence capture of mackerel would require more effort. There would be more fuel expenditure on mackerel capture keeping this fish away from the nets and plates of poor fishermen as capture of this fish would require operation of bottom trawlers which would be out of the reach of poor fishermen. Operation of trawlers and increased effort would also make this fish expensive and hence out of the reach of poor population residing along the coast.
Indian coral reefs have experienced 29 widespread bleaching events since 1989 and intense bleaching occurred in 1998 and 2002 when the SST was higher than the usual summer maxima. If the same trend continues then reef building corals are likely to disappear as dominant organisms on coral reefs between 2020 and 2040 and the reefs are likely to become remnant between 2030 and 2040 in the Lakshadweep sea and between 2050 and 2060 in other regions in the Indian seas. Along with the elimination of this ecological habitat will also be eliminated the local fishery of these region and other livelihood (depending on tourism) of people living there. Globally, climate change has been a matter of debate in the fisheries community due to its potential impact on the fish production. It has been observed that the north wall (northern boundary) of the Gulf Stream has been undergoing a displacement south since the late 1990s, and the speed and amplitude of the change appears to support the hypothesis that there was a regime shift in the climate of the North Atlantic Ocean. It is possible that a continued displacement south of the north wall of the Gulf Stream will lead to further increases in river discharge, reductions in water temperature and reduced ﬁsh growth and recruitment success in the long term.
Due to anthropogenic activities like building of dams, diverting of river course there has been destruction of fish habitat and breeding grounds. This has a profound influence on the fishermen populations living along the banks of the rivers. Lakes are being polluted due to dumping of industrial waste and other types of human wastes resulting from human sewage system, tourism activities etc. This has implications on food security due to poor fish catches from lakes and rivers. Construction of dams have obstructed the river flow leading to inundation of breeding grounds, altered flow rate, water salinity changes, changes in turbidity levels and water productivity, change in the aquatic fauna. Farraka barrage in West Bengal over river Ganga has resulted in serious declines in prized fish catches like Hilsa upstream (Sinha et al. 1996).
Mangrove, which are the natural breeding grounds for thousands of species not only of aquatic world but also for terrestrial animals like the Sunderban tigers and many types of birds. It is a closely knit structured community. Mangroves are being threatened by the changes in climate and hence is threatened the existence of thousands of other species. Climate change components that affect mangroves include changes in sea-level, high water events, storminess, precipitation, temperature, atmospheric CO2 concentration, ocean circulation patterns, health of functionally linked neighboring ecosystems, as well as human responses to climate change (Gilman et al, 2008). Sea level rise is the most eminent threat to the estuarine and mangrove fishery. Higher sedimentation rate and increased salinity of the water due to higher tidal influence will have potentials to eliminate breeding grounds. This will affect the fish and shell fish breeding, fish recruitment, fish catches, economy of the coastal areas. Salt ingress will also affect the agriculture negatively. Increased runoff and flooding has also been associated with changing climate which will have unfavourable effects on agriculture and fishery of India affecting food security.
Gilman, E.L. Ellison, J. Duke, N.C. Field, C. Threats to mangroves from climate change and adaptation options: A review. Aquatic Botany 89 (2008) 237–250.
Hinrichsen, D. (United Nations Consultant). 1999. The coastal population explosion. In: Trends and Future Challenges for U.S. National Ocean and Coastal Policy: Proceedings of a Workshop (Washington, D.C.), pp. 27–29.
Jhingran, A.G. Gupta, R.A. Status and dynamics of Hilsa (Hilsa ilisha) in the Hooghly estuarine system, West Bengal, India, Contribution to tropical fish assessment in india, GCP/INT/392/DEN, pp. 102-114, 1987.
Mall, R.K. Gupta, A. Singh, R. Singh, R.S. Rathore, L.S. Water resources and climate change: An Indian perspective. Current science (2006) 90-12. 1610 – 1626.
Nunn, A.D. Frear, P.A. Lee, M. Cowx, I.G. Is there evidence for a shift in ﬁsh growth and recruitment success linked to climate change? Journal of Fish Biology (2010) 77, 1780–1792.
Prasannakumar, S., Roshin , R.P., Narvekar, J. , Dineshkumar, P.K. and Vivekanandan, E. (2009) Is Arabian Sea responding to global warming and undergoing a climate shift? In : Book of Abstracts: Marine Ecosystems Challenges and Opportunities, 9-12 February 2009, Cochin , p. 248-249, Marine Biological Association of India, Cochin
Sannadurgappa, D. Vulnerability of freshwater fisheries and impacts of climate change in south Indian states economies. Interdis. Environ. Rev.(2011), 12 – 4; 283-297.
Sinha, M. Mukhopadhya, M.K. Mitra, P.M. Baghchi, M.M. Karamkar, H.C. Impact of Farakka barrage on the hydrology and fishery of Hoogly estuary. Estuaries and coasts (1996) 19-3, 710-722.
Trenberth, K. E., Nat. Implications Environ. Change, 1999, 5, 2–15.
Vivekanandan , E., Hussain Ali, M., Rajagopalan, M. (2009) Vulnerability of corals to seawater warming, In: Impact, Adaptation and Vulnerability of Indian agriculture to climate change (Aggarwal , P.K., Ed.), Indian Council of Ag,rJcultu ral Research , New Delhi.
Vivekanandan E, and Rajagopalan, M. (2009) Impact of rise in seawater temperature on the spawning of threadfin breams, In: Impact, Adaptation and Vulnerability of Indian agriculture to climate change Aggarwal, P.K., Ed.), Indian Council of Agricultural Research, New Delhi.
Vivekanandan, E., Rajagoparan , M., Pillai, N.G.K. (2009) Recent trends in sea surface temperature and its impact on oil sardine. In : Impact, Adaptation and Vulnerability of Indian agriculture to climate change (Aggarwal, P.K., Ed.), Indian Council of Agricultural Research, New Delhi.