Change is the law of nature and the earth has witnessed it for billions of years. As it was a natural and gradual process then, so the ecosystem could adapt to the change without any negative effect but the increased human interference in the present times has disrupted the nature’s balance. The world is progressing at a faster pace with new and efficient technologies at the cost of serious environmental damage. Climate change is one such problem faced by the world. According to article 1 of United Nations Framework on Climate change (UNFCC), “Climate change” means a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods.” To deal with the problem we need to firstly understand the concept of climatic change and the threat it poses.
The atmosphere consists of gases like Nitrogen (78%), Oxygen (21%), Carbon dioxide (0.04%) and traces of other gases. Sun is the source of all energy. Green house gases (GHGs) like Carbon dioxide (CO2), Nitrous Oxide (N2O), Methane (CH4), water vapour, ozone etc help to maintain balance of temperature on earth. When sunlight reaches the earth, some of it is radiated back to space as infrared radiation (heat). Greenhouse gases absorb it and trap the heat in the atmosphere. If there were no GHGs, the earth would be cold. There is now increased concentration of these gases leading to rise in temperature more because of anthropogenic causes than the natural ones like volcanic eruptions and solar variations. Hydroflourocarbons, Perflourocarbons and Sulpher hexafluoride are man-made greenhouse gases.
The period of 1998-2007 was recorded as the warmest decade. A number of factors can be listed for climate change. Plants and trees help to clean the air by absorbing harmful gases but practice of cutting down forests poses a grave threat. Carbon dioxide is released when wood is burnt and Methane when wood rots. Livestock cattle, oil drilling, coal mining, gas pipelines, and rice padding contribute to increase in methane. Fossil fuel power plants emit GHGs. Release of N2O takes place through fertilizers and land use changes. Vehicles have made life comfortable but they depend on fossil fuels like petrol and diesel. Ozone layer provides protection from harmful ultraviolet rays of the sun and its depletion causes cooling. Chlorofluorocarbons (CFCs) used in refrigerators; air-conditioners etc however cause ozone depletion. Polythene is yet another cause of concern. Rapid Industrialisation has made us to compromise with environment by causing air pollution. Toxic wastes are released in the rivers. All the above reasons have resulted in serious threats: 1) Droughts and decrease in water level in the major rivers of the world have been reported. 2) Heavy precipitation in the world’s upper latitudes and lower precipitation in some sub-tropical and tropical regions and in the Mediterranean Sea. 3) Heat waves. 4)Tropical cyclones. 5) Storms. 6) Displacement of people living in coastal or flood prone areas. 7) Rise in sea level threatens the freshwater. It is expected to rise by 22-35 mm by the end of this century. Small Islands like Maldives and Srilanka are under threat of disappearing. 8) Several species are on verge of extinction.9) Melting of polar ice caps 10) Melting of glaciers causing floods. Himalayan glaciers support river Ganges, Indus and Brahmputra, which in turn feed millions of people in South Asia. Gangotri glacier has melted by 850 m. It is reducing by 17 m a year. Countries like Nepal and Bhutan are under risk of floods.11) Changes in seasonal pattern. 12) Increase risk of diseases like malaria and dengue. 13) Degradation of coral reefs because of sewage, toxic discharge from boats, fertilizers, pesticides etc. Heat prevents shell formation. 14) United nations Environmental Programme (UNEP) Report, 2008 has warned about brown clouds released by burning fossil fuels, woods, and plants that become black carbon and soot, which further absorb sunlight and warm the temperature. 15) Forests have for long acted as carbon sinks or reservoirs. Cutting down tropical forests like Amazon would release greenhouse gases. They have also become vulnerable to disease, insect infestations, and fire. 16) Building of dams and diversion of rivers for agriculture. 17) Arctic Ocean is getting warmer. 18) Deltas are sinking. Brahamani delta in Orissa, Godavari and Mahanadi in Andhra Pradesh are under threat. Construction of dams or reservoirs etc blocks sedimentation and affect deltas. 19) Water shortage increases risk of food shortage and desertification. Scarcity can further lead to conflicts between countries.