These proceedings contain 270 papers outlining ideas and contributions to the new scientific, technical and political discipline of Greenhouse Gas (GHG) Control. The contributions were presented at the 4th International Conference on Greenhouse Gas Control Technologies (GHGT-4). It was the largest gathering of experts active in this new and fast-developing field.GHGT-4 was different from its predecessors in that it included all greenhouse gases, not only CO2, and all issues which could contribute to the mitigation of the greenhouse problem - technical, economic and political. The main focus was on practical solutions and real demonstrations of mitigation technology being planned and implemented today. It also addressed ways to increase the efficiency of power production and utilisation, and looked at proposals to encourage the development of renewable energy sources.During the Opening Session, 10 keynote addresses were heard from prominent personalities in government, industry and academia. To tackle this very inter-disciplinary problem and to achieve acceptable solutions, it is essential for industry and government to initiate intense dialogue and cooperation. Conferences like this can provide the opportunity for a meeting of minds between engineers and politicians in the face of global challenge. The primary attributes of this global challenge are manifold: the problem is global and international; it is inter-disciplinary, both in substance and approach; it covers technical, political and economic issues and involves government, science, industry and academia; it is complex and non-linear; and it will take the efforts of all parties involved to solve the problem.These proceedings contain ideas for starting demonstration projects and for making better use of the power and flexibility of market measures. They also show it is a problem we can influence and that there is a wealth of ideas. The challenge now is to find the right partners to put these ideas into action.