1) Ethics/International Relations In a number of the articles related to geoengineering, discussion is focused on the ethical implications of engineering the climate. These works build on the accepted base of knowledge about climate systems. The questions addressed in these articles range from international relations (who has the right to make such decisions) to whether the very act of modifying the climate is ethically justifiable. This area is given attention by researchers due to its strong implications on policy.
2) Aerosol Use/Modeling The research on aerosols and their effects on feedback loops revolves around the concept of a radiative balance. Articles in this cluster, like Charlson's 2002 "Perturbation of the northern hemisphere radiative balance by backscattering from anthropogenic sulfate aerosols", use calculations of aerosol mass concentration and back-scattering to model the effectiveness of the aerosols without making the step of suggesting action as their fellow clusters do. This is the basis for the policy recommendations that are made later on in the process. These articles were found in highly technical, discipline-specific publications (e.g. oceanography journals).