This is the first book to provide measurements of greenhouse gases from both aquatic and terrestrial environments as well as from hydroelectric reservoirs. This monograph not only presents the state-of-the-art techniques for measuring the emissions of greenhouse gases, but also demonstrates the mechanisms or processes leading to the emissions of greenhouse gases. It offers the reader a synthesis of what we understand of GHG emission after 12 years of research in boreal ecosystems, the estimations of gross and net emissions from hydroelectric reservoirs, the impact of hydroelectric reservoirs on climate change, as well as a comparison of the different alternatives for producing energy in relation to GHG emissions.