Global warming, the real challenge for the new millennium, is defined as the increase in the of the Earth's near-surface air and in recent decades and its projected continuation. Global average air temperature near the Earth's surface rose 0.74 0.18°C (1.3 ± 0.32°F) during the past century. Since 1980, the earth has experienced 19 of its 20 hottest years on record, with 2005 and 1998 tied for the hottest and 2002 and 2003 coming in second and third.

 In 2003, extreme heat waves caused more than 20,000 deaths in Europe and more than 1500 deaths in India. More than 250 people died as a result of an intense heat wave that gripped most of the eastern two-thirds of the United States in 1999.Sea Ice thickness has reduced to just 54% of that existed in 1955. The current pace of sea-level rise is three times the historical rate and appears to be accelerating. Global sea level has already risen by four to eight inches in the past century. Scientists' best estimate is that sea level will rise by an additional 19 inches by 2100, and perhaps by as much as 37 inches. The (IPCC) concludes, "most of the observed increase in globally averaged temperatures since the mid- 20th century is very likely the observed increase in greenhouse gas concentrations," which leads to warming of the surface and lower atmosphere by increasing the. It predicted effects for and for are numerous and varied. The main effect is an increasing global average temperature, which in turn causes a variety of resulting effects, namely, rising sea levels, altered patterns of, increased events, and the expansion of the range of tropical diseases. In some cases, the effects may already be occurring, although it is generally difficult to attribute specific natural phenomena to long-term global warming.

The graph indicates a strong correlation between carbon dioxide content in the atmosphere and temperature. A possible scenario: anthropogenic emissions of GHGs could bring the climate to a state where it reverts to the highly unstable climate of the pre-ice age period. Rather than a linear evolution, the climate follows a non-linear path with sudden and dramatic surprises when GHG levels reach an as-yet unknown trigger point. As Dr. Robert Watson, then Chairman of the Intergovernmental Panel on Climate Change, said in 2001, "The overwhelming majority of scientific experts, whilst recognizing that scientific uncertainties exist, nonetheless believe that human-induced climate change is already occurring and that future change is inevitable."

The present atmospheric concentration of CO2 is about 383 parts per million (ppm) by volume at global average. With a quantum jump in total fossil-fuel CO2 emissions, India ranks fourth in the world as per 2003 data. Future CO2 levels are expected to rise due to ongoing burning of fossil fuels and land-use change. The rate of rise will depend on uncertain economic, sociological, technological, natural developments, but may be ultimately limited by the availability of fossil fuels. The amount of CO2 released Êinto the atmosphere in the next 30 years is expected to double or triple. The number of cars in operation around the world will double by the year 2030. The IPCC gives a wide range of future CO2 scenarios, ranging from 541 to 970 ppm by the year 2100. Fossil fuel reserves are sufficient to reach this level and continue emissions past 2100, if coal, tar sands or are extensively used.

Coal is the most carbon-intense of fossil fuels. Reducing use of coal through energy efficiency and renewable energy technologies will be the cornerstones of the solution to global warming, but the plain truth is that hundreds of new coalfired power plants will probably be constructed around the world in coming years. Coal generates more than half of the electricity we use today, and it is in plentiful supply in such countries as China, India and the United States.

While the sustainable development is constrained by the Global Warming phenomenon, its positive (sea-level rise) may contaminate , affecting drinking water and agriculture in coastal zones. Increased evaporation will reduce the effectiveness of reservoirs. Increased extreme weather means more water falls on hardened ground unable to absorb it, leading to flash floods instead of a replenishment of soil moisture or groundwater levels. In some areas, shrinking glaciers threaten the water supply. Higher temperatures will also increase the demand for water for the purposes of cooling and hydration.

 "Rising atmospheric temperatures, longer droughts and side effects of both, such as higher levels of ground-level ozone gas, are likely to bring about a substantial reduction in crop yields in the coming decades, large-scale experiments have shown" (, , 2005.)

The increase in global temperatures is expected to disrupt ecosystems and result in loss of species diversity, as species that cannot adapt die off. The first comprehensive assessment of the extinction risk from global warming found that more than one million species could be committed to extinction by 2050 if global warming pollution is not curtailed.

The combined effects of global warming may impact particularly harshly on people and countries without the resources to those effects. This may slow and , and make it harder to achieve the . Many estimates of aggregate net economic costs of damages from climate change across the globe, the social cost of carbon (SCC), expressed in terms of future net benefits and costs that are discounted to the present, are now available. Peer-reviewed estimates of the SCC for 2005 have an average value of US$43 per tonne of carbon (tC) (i.e., US$12 per tonne of carbon dioxide) but the range around this mean is large.

In water scarce regions ‘thirst’ becomes equally relevant as ‘hunger’ in other parts. Any plan of sustainable development of such region is incomplete without quenching thirst first. Plight of the people in such water scarce regions need to be empathized before imparting them any lesson on environmental management of a developmental process.

Socioeconomic imbalances induced by water scarcity seriously constraint the sustainability of the developmental process and impairs the quality of life, which in turn degrades the environment. Water and Energy are two requisites for development having strong inter-linkages such that shortage/scarcity of one could severely unbalance the equilibrium of the other in terms of demand-supply scenario.

Gujarat State, having geographical area of 19.6 million ha and current population of about 58 million, is located in the western part of India between 20.60o and 24.42o north latitude and 68.10o and 74.8o east longitude. It is relatively urbanized and economically progressive state having its per capita income 31% higher than the national average.

Groundwater recharge

Groundwater recharge by an array of water releases (rivers, tanks, agricultural farms and special recharge wells) has yielded positive results. In the areas where yearly depletion was 2 to 3 m, it has been checked and even reversed with net increase in the ground water tables. Defunct wells have been rejuvenated and availability of ground water at lesser depths in some areas have helped reducing electricity consumption – indirectly reducing pressure on thermal power generation and thus reducing pollution.

Release of significant quantity of Narmada water in the dry bed of at least twelve other rivers of the state has helped in flushing out the pollutants in the river stretches which was not possible since quite some years for want of adequate rainfall and runoff. This has improved the quality of water to a considerable extent. Millions of people have been saved from forceful drinking of poor quality water containing excessive fluoride, nitrate or salinity.

Reducing emissions has become a statutory requirement following the Kyoto Protocol of December, 1997 which was signed and ratified by India in August 2002. It may be noted here that even after observing the environmental control regulations on permissible limits of emission, a thermal power plant of same installed capacity would throw out in air, 6571400 tonnes of CO2, 10780 tonnes of suspended particulate matter and 25700 MT of sulphur dioxide per year. Social cost of CO2 alone would be of the tune of 80 million USD. Thus Sardar Sarovar Project helps in preventing such pollution and thereby enriching the environment.

Wetlands & Sanctuaries benefited

Attempts have been made to extend the benefits of the Project to various sanctuaries by supplying water from the nearest canal segment. Wherever canal is not passing through such areas, water supply arrangements through pipelines on conservative basis have been made. Wild Ass Sanctuary in the desert of Kutch will have habitat conservation opportunity by receiving Narmada water. Part of Shoolpaneshwar sanctuary forms the catchment area of Narmada river. It was therefore studied in detail implementation of which improved habitat conditions and reduced biotic pressures. There has been suitable increase in some rare wildlife viz. Barking Deer, Four horned Antelope, Slothbear, Giant Squirrel, Grey Hornbill, Grey Jungle Fowl etc. Nal Sarovar, the unique wetland eco-system and world famous bird sanctuary is also going to be benefited by Narmada water which will be supplied through Saurashtra Branch Canal. With the availability of canal water round the year and even during droughts, there is likelihood of constant annual migration of birds promoting eco-tourism and thereby indirectly helping in livelihood of local people. Velavadar National Park of Black Bucks (Antilope cervicapra) has also been benefited by various measures being taken in the park area. With great improvement in the grassland species, palatable grasses and herbs, Velavadar now holds one of

 the largest populations of Black Buck. Population of Lesser Florican (Sypheotides Indica) has increased many folds besides number of Wolfs. World’s largest communal roost of wintering Harriers now migrates to Velavadar Park every year.

 Sardar Sarovar Project will annually supply 11.7 billion cubic meter (BCM) of water to the mostly drought prone areas of Gujarat and neighboring Rajasthan states. Water mining conditions existing in most of these areas are responsible for consumption of at least 3000 MW of electricity for extracting groundwater. The assured water supply will help reduce the dependence on groundwater in these areas and thereby save this electricity. This means reduction in carbon dioxide of 13,596,000 tonnes per year! Further, as water is invariably required for generation of electricity, saving in electricity leads to further saving in water, which in turn helps in further saving of electricity. Thus assured water supplies through Sardar Sarovar Project will have rippling effects in saving of electricity and thereby reduction in carbon emissions.

Socioeconomic Impact : Controlling Greenhouse Effect

 With 37.36% of its population living in urban centres, Gujarat is one of the most urbanized states of India. Urban population was 5.3 million people when the state came into being in 1960, which has increased to 18.9 million in 2001 Census, registering more than 250% growth in just four decades. To accommodate such a huge population, not only the numbers of cities have grown, but also the size of individual cities. This has eventually necessitated more transportation facilities and associated fuel consumptions and carbon emissions. Even during last 25 years, total length of road network in the state has doubled whereas total number of registered motor vehicles has increased 18 times. These figures speak about the increasing vehicle density, traffic congestion and air pollution. Because of heavy traffic and industrial emission, greenhouse effect is sure to grip the environment and hence maintaining socioeconomic conditions and living pattern is mandatory to maintain the environmental quality standards.