A speculation is an idea or a thought that will be more available in the future and has at present a theoretical rather than practical viewpoint. As the regions in the earth will be beyond the reaches of scientific knowledge is a not yet proven and nor is it completely investigated.
1. Fracking 2. Air pollutants. 3. Decomposition of organic matter e.g. in landfills. 4. <span>Chlorofluorocarbons </span>mainly in refrigerants and air conditioners.
