Global climate change has emerged as a major scientific and political issue within a few short decades. Scientific evidence clearly indicates that this change is a result of a complex interplay between a number of human-related and natural earth systems. While the complexity of the earth-ocean-atmosphere system makes the understanding and prediction of global climate change very difficult, improved scientific knowledge and research capabilities are advancing our understanding of global climate change resulting from rising atmospheric levels of radiatively important (mostly heat-trapping) gases and particles. The effects of climate change can be assessed with climate models, which account for complex physical, chemical and biological processes, and interactions of these processes with human activities, especially the burning of fossil fuels along with land use changes. Such an approach is collectively known as Integrated Assessment. An integrated assessment model framework has a potential to explore the interactions between human dimension, the terrestrial and ocean carbon cycle, the Earth climate system, and various mitigation strategies such as ocean and terrestrial carbon sequestrations. We are developing an Integrated Science Assessment Model (ISAM) for use in an Integrated Assessment framework. This talk will demonstrate the use of this modeling capability through its applications to study the full range of interactions between climate and biogeochemical cycle components (e.g., carbon and nitrogen cycles) in Earth system.