Climate change and the occurrence of extreme weather conditions are the major concepts which are linked to global warming. The hydropower has been considered as clean source of energy by recent studies has proven that the creation of a dam along a water body will result in the greenhouse gases (GHGs) emission which is answerable for global warming. The OM originates from the flooded area, acts as the primary production in the reservoir which flows from upstream to downstream part of the reservoir. The multiple pathways in which the gases  reach  the  atmosphere  are  in  diffusing flux, bubbling, flux through macrophytes and  in  the  upstream and  downstream of the reservoir itself. A large amount of gases is also released into the atmosphere when the water is passing the turbine and the spillway. When globally compared some reservoirs, emission are very high when compared with thermo-power plants. In this paper past 16 years data of seven hydro power stations which are in India at different climatic zones has been analyzed. A mean annual daily temp from past 16years (1997-2012) has been analyzed for seven hydro power stations in India Similarly for rainfall, mean annual rainfall over 16 years being obtained. And finally, by using UNESCO/IHA GHG Risk Assessment Tool (Beta Version) speculated diffusive fluxes in CO2eq has been calculated for that particular year and predicted values over hundred years for the selected hydro power stations are also obtained using the same tool.